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Draggendrop    5,747

Sharpest View Ever of Dusty Disc Around Aging Star

 

eso1608a.jpg

IRAS 08544-4431              ESO

 

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As they approach the ends of their lives many stars develop stable discs of gas and dust around them.

 

This material was ejected by stellar winds, whilst the star was passing through the red giant stage of its evolution. These discs resemble those that form planets around young stars. But up to now astronomers have not been able to compare the two types, formed at the beginning and the end of the stellar life cycle.

 

Although there are many discs associated with young stars that are sufficiently near to us to be studied in depth, there are no corresponding old stars with discs that are close enough for us to obtain detailed images.

 

But this has now changed. A team of astronomers led by Michel Hillen and Hans Van Winckel from the Instituut voor Sterrenkunde in Leuven, Belgium, has used the full power of the Very Large Telescope Interferometer (VLTI) at ESO's Paranal Observatory in Chile, armed with the PIONIER instrument, and the newly upgraded RAPID detector.

 

Their target was the old double star IRAS 08544-4431 [1], lying about 4000 light-years from Earth in the southern constellation of Vela (constellation) (The Sails). This double star consists of a red giant star, which expelled the material in the surrounding dusty disc, and a less-evolved more normal star orbiting close to it.

 

Jacques Kluska, team member from Exeter University, United Kingdom, explains: "By combining light from several telescopes of the Very Large Telescope Interferometer, we obtained an image of stunning sharpness -- equivalent to what a telescope with a diameter of 150 metres would see. The resolution is so high that, for comparison, we could determine the size and shape of a one euro coin seen from a distance of two thousand kilometres."

 

Thanks to the unprecedented sharpness of the images [2] from the Very Large Telescope Interferometer, and a new imaging technique that can remove the central stars from the image to reveal what lies around them, the team could dissect all the building blocks of the IRAS 08544-4431 system for the first time.

 

The most prominent feature of the image is the clearly resolved ring. The inner edge of the dust ring, seen for the first time in these observations, corresponds very well with the expected start of the dusty disc: closer to the stars, the dust would evaporate in the fierce radiation from the stars.

"We were also surprised to find a fainter glow that is probably coming from a small accretion disc around the companion star. We knew the star was double, but weren't expecting to see the companion directly. Itis really thanks to the jump in performance now provided by the new detector in PIONIER, that we are able to view the very inner regions of this distant system," adds lead author Michel Hillen.

 

The team finds that discs around old stars are indeed very similar to the planet-forming ones around young stars. Whether a second crop of planets can really form around these old stars is yet to be determined, but it is an intriguing possibility.

 

"Our observations and modelling open a new window to study the physics of these discs, as well as stellar evolution in double stars. For the first time the complex interactions between close binary systems and their dusty environments can now be resolved in space and time," concludes Hans Van Winckel.

more at the link...

http://spaceref.com/astronomy/sharpest-view-ever-of-dusty-disc-around-aging-star.html

 

http://www.eso.org/public/news/eso1608/

 

eso1608b.jpg

The dusty ring around the aging double star IRAS 08544-4431                ESO

 

 

eso1608c.jpg

The aging double star IRAS 08544-4431 in the constellation of Vela (The Sails)                   ESO

 

:D

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Draggendrop    5,747

Clocking the rotation rate of a supermassive black hole

 

110849_web.jpg

CAPTION
An illustration of the binary black hole system in OJ287. The predictions of the model are verified by observations.
CREDIT
Gary Poyner, UK
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A recent observational campaign involving more than two dozen optical telescopes and NASA's space based SWIFT X-ray telescope allowed a team of astronomers to measure very accurately the rotational rate of one of the most massive black holes in the universe. The rotational rate of this massive black hole is one third of the maximum spin rate allowed in General Relativity. This 18 billion solar mass heavy black hole powers a quasar called OJ287 which lies about 3.5 billion light years away from Earth. Quasi-stellar radio sources or `quasars' for short, are the very bright centers of distant galaxies which emit huge amounts of electro-magnetic radiation due to the infall of matter into their massive black holes.

 

This quasar lies very close to the apparent path of the Sun's motion on the celestial sphere as seen from Earth, where most searches for asteroids and comets are conducted. Therefore, its optical photometric measurements already cover more than 100 years. A careful analysis of these observations show that OJ 287 has produced quasi-periodic optical outbursts at intervals of approximately 12 years dating back to around 1891. Additionally, a close inspection of newer data sets reveals the presence of double-peaks in these outbursts.

 

These deductions prompted Prof. Mauri Valtonen of University of Turku, Finland and his collaborators to develop a model that requires the quasar OJ287 to harbour two unequal mass black holes. Their model involves a massive black hole with an accretion disk (a disk of interstellar material formed by matter falling into objects like black holes) while the comparatively smaller black hole revolves around it. The quasar OJ287 is visible due to the slow accretion of matter, present in the accretion disk, onto the largest black hole. Additionally, the small black hole passes through the accretion disk during its orbit which causes the disk material to heat up to very high temperatures. This heated material flows out from both sides of the accretion disk and radiates strongly for weeks. This causes peaks in the brightness, and the double peaks arise due to the ellipticity of the orbit, as shown in the figure.

 

The binary black hole model for OJ287 implies that the smaller black hole's orbit should rotate, and this changes where and when the smaller hole impacts the accretion disk. This effect arises from Einstein's General Theory of Relativity and its precessional rate depends mainly on the two black hole masses and the rotation rate of the more massive black hole. In 2010, Valtonen and collaborators used eight well timed bright outbursts of OJ287 to accurately measure the precession rate of the smaller hole's orbit. This analysis revealed for the first time the rotation rate of the massive black hole along with accurate estimates for the masses of the two black holes. This was possible since the smaller black hole's orbit precess at an incredible 39 degrees per individual orbit. The General Relativistic model for OJ287 also predicted that the next outburst could occur around the time of GR Centenary, 25 November 2015, which marks the 100th anniversary of Einstein's General Theory of Relativity.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/tiof-ctr031016.php

 

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Mysterious infrared light from space resolved perfectly

 

110851_web.jpg

On the left is an artist's impression of the Cosmic Infrared Background resolved with ALMA. On the right is a diagram that shows that the sum of the emissions from the faint objects detected with ALMA reaches the CIB measured with satellite observations.
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NAOJ
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A research team using the Atacama Large Millimeter/submillimeter Array (ALMA) has detected the faintest millimeter-wave source ever observed. By accumulating millimeter-waves from faint objects like this throughout the Universe, the team finally determined that such objects are 100% responsible for the enigmatic infrared background light filling the Universe. By comparing these to optical and infrared images, the team found that 60% of them are faint galaxies, whereas the rest have no corresponding objects in optical/infrared wavelengths and their nature is still unknown.

 

The Universe looks dark in the parts between stars and galaxies. However, astronomers have found that there is faint but uniform light, called the "cosmic background emission," coming from all directions. This background emission consists of three main components; Cosmic Optical Background (COB), Cosmic Microwave Background (CMB), and Cosmic Infrared Background (CIB).

 

The origins of the first two have already been revealed. The COB comes from a huge number of stars, and the CMB comes from hot gas just after the Big Bang. However, the origin of the CIB was still to be solved. Various research projects, including past ALMA observations, have been conducted, but they could only explain half of the CIB.

 

A research team led by a graduate student, Seiji Fujimoto, and an associate professor, Masami Ouchi, at the University of Tokyo, tackled this mysterious infrared background by examining the ALMA data archive. ALMA is the perfect tool to investigate the source of the CIB thanks to its unprecedented sensitivity and resolution.

 

They went through the vast amount of ALMA data taken during about 900 days in total looking for faint objects. They also searched the datasets extensively for lensed sources, where huge gravity has magnified the source making even fainter objects visible.

 

"The origin of the CIB is a long-standing missing piece in the energy coming from the Universe," said Seiji Fujimoto, now studying at the Institute of Cosmic Ray Research, the University of Tokyo. "We devoted ourselves to analyzing the gigantic ALMA data in order to find the missing piece."

Finally, the team discovered 133 faint objects, including an object five times fainter than any other ever detected. The researchers found that the entire CIB can be explained by summing up the emissions from such objects (note).

 

What is the nature of those sources? By comparing the ALMA data with the data taken by the Hubble Space Telescope and the Subaru Telescope, the team found that 60% of them are galaxies which can also be seen in the optical/infrared images. Dust in galaxies absorbs optical and infrared light and re-emits the energy in longer millimeter waves which can be detected with ALMA.

 

"However, we have no idea what the rest of them are. I speculate that they are galaxies obscured by dust. Considering their darkness, they would be very low-mass galaxies." Masami Ouchi explained passionately. "This means that such small galaxies contain great amounts of dust. That conflicts with our current understanding: small galaxies should contain small amounts of dust. Our results might indicate the existence of many unexpected objects in the distant Universe. We are eager to unmask these new enigmatic sources with future ALMA observations."

 

Note: ALMA detected a part of the CIB with 1 mm wavelengths. The CIB in millimeter and submillimeter waves does not become weak even if the source is located far away. Therefore this wavelength is suitable for looking through the Universe to the most distant parts.

http://www.eurekalert.org/pub_releases/2016-03/nion-mil031016.php

 

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Unobscured Vision    2,676

Well, well. That's certainly in line with what other observations are saying; and even the "size" of the Universe (40-something-odd billion light-years across) not jiving with the reputed age of the Universe (said to be 13.7~14.1 billion years) was a big problem. Now we're getting data that says that the CMB itself isn't what they thought it was before, and the age of the Universe (obviously) isn't what they thought it was either.

 

Good. Now the theories and hypotheses don't have to rely on non-relativistic functions, and they get to revise the age estimates more precisely when the new gear is available. I'll tell ya this much, folks -- that estimate is gonna be closer to the 20 billion year mark than people think if not past it.

 

I kinda figured something was up when HST was able to detect GN-z11 at a redshift of 11.1 when theoretically it shouldn't have been able to ... now we know why. :yes: 

 

Okay, HST -- you folks found yourselves an extended mission, for as long as the telescope and the WFP and NIR/UV components can hold out -- find as many r-11.0 and lower objects that you can, and start compiling the targets for JWST. That one needs them.

 

I'd really like to see one more Servicing Mission to HST once the Manned Dragon program is up and running. HST is proving to have some Science Value left in it, but it needs a refill on the coolant and maybe some servicing. Nothing major yet. 

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Draggendrop    5,747

Hubble Unveils Monster Stars

 

heic1605a.jpg

R136                STSCI

 

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Astronomers using the unique ultraviolet capabilities of the NASA/ESA Hubble Space Telescope have identified nine monster stars with masses over 100 times the mass of the Sun in the star cluster R136.

 

This makes it the largest sample of very massive stars identified to date. The results, which will be published in the Monthly Notices of the Royal Astronomical Society, raise many new questions about the formation of massive stars.

 

An international team of scientists using the NASA/ESA Hubble Space Telescope has combined images taken with the Wide Field Camera 3 with the unprecedented ultraviolet spatial resolution of the Space Telescope Imaging Spectrograph to successfully dissect the young star cluster R136 in the ultraviolet for the first time [1].

 

R136 is only a few light-years across and is located in the Tarantula Nebula within the Large Magellanic Cloud , about 170,000 light-years away. The young cluster hosts many extremely massive, hot and luminous stars whose energy is mostly radiated in the ultraviolet [2]. This is why the scientists probed the ultraviolet emission of the cluster.

 

As well as finding dozens of stars exceeding 50 solar masses, this new study was able to reveal a total number of nine very massive stars in the cluster, all more than 100 times more massive as the Sun. However, the current record holder R136a1 does keep its place as the most massive star known in the universe, at over 250 solar masses. The detected stars are not only extremely massive, but also extremely bright. Together these nine stars outshine the Sun by a factor of 30 million.

 

The scientists were also able to investigate outflows from these behemoths, which are most readily studied in the ultraviolet. They eject up to an Earth mass of material per month at a speed approaching one percent of the speed of light, resulting in extreme weight loss throughout their brief lives.

More at the link...

http://spaceref.com/astronomy/hubble-unveils-monster-stars.html

 

http://www.spacetelescope.org/images/heic1605a/

 

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Milky Way’s black hole may be spewing out cosmic rays

 

Shot_Black-Hole.jpg?itok=-FmLPgZJ&timest

Observations have shown for the first time that something in the vicinity of a supermassive black hole can accelerate protons to superhigh energy.

ESO/L. Calçada

 

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Mysterious high-energy particles known as cosmic rays zip through space at a wide range of energies, some millions of times greater than those produced in the world’s most powerful atom smasher. Scientists have long thought cosmic rays from inside our galaxy come from supernova explosions, but a new study has fingered a second source: the supermassive black hole at the heart of the Milky Way. With this new result, the search for cosmic ray origins, which has frustrated scientists for more than 100 years, has taken an unexpected new twist.

 

“It’s very exciting,” says astrophysicist Andrew Taylor of the Dublin Institute for Advanced Studies. “This has probably shaken the field quite a lot. People will need to reassess their models.”

 

Cosmic rays pose a mystery for astronomers because they don’t follow a straight path through space. They get tugged and pushed by magnetic fields, so it is almost impossible to figure out where particular particles have come from. So instead, researchers have looked at gamma rays, high-energy photons that are thought to be produced at or near the source of the cosmic rays. Find out where the gamma rays come from, and you’ve probably found the source of cosmic rays.

 

Although many of the cosmic rays from within our galaxy appear to be blasted out from supernova explosions at blistering speeds, such explosions can’t explain the highest energy cosmic rays: those with energies measured in peta-electronvolts (PeV, or 1015 eV). (Here on Earth, 1 PeV is the total energy that the Large Hadron Collider can achieve when slamming together lead ions.)

 

“We don’t really know what’s going on,” says Werner Hofmann of the Max Planck Institute for Nuclear Physics in Heidelberg, Germany.

The difficulty in studying both cosmic rays and their accompanying gamma rays, however, is that they get destroyed by colliding with atoms high in the atmosphere and never reach Earth’s surface. These collisions do, however, send showers of other particles raining down toward the surface. Astronomers can measure the spread of those particles with detectors on the ground, or capture flashes of light called Cherenkov radiation, which the particles give off as they decelerate in the atmosphere.

 

In the new study, Hofmann and colleagues used the High Energy Stereoscopic System (HESS), an array of five telescopes in Namibia, which can detect such radiation. HESS has been studying the galactic center for about a decade, Hofmann says, simply because it is an interesting source of gamma rays. In recent years, his team has carried out more detailed observations. And, as it reports online today in Nature, the distribution of gamma rays coming from around the galactic center is exactly what you would expect if some process, close to the black hole, is firing out protons with PeV energies.

 

Many of those protons may much later arrive at Earth as PeV cosmic rays, but some are colliding with gas molecules close to their source and producing gamma rays. It is these gamma rays HESS is able to pick up, revealing the origin of these superfast protons. “It really demonstrates that there is a central source [of protons],” Hofmann says.

 

“This is a great result. It’s very fascinating,” says astrophysicist Pasquale Blasi of the Arcetri Astrophysical Observatory in Florence, Italy. “For the very first time we have almost direct evidence of the acceleration of protons to these energies.” But he cautions that it has not yet been proved that these same protons make it all the way to Earth as cosmic rays. Over such a distance, there is a high probability that they can diffuse out of the halo of the galaxy and escape. There are ways to detect cosmic rays en route between the galactic center and here, but “we may need to think outside the box,” he says.

more at the link...

http://www.sciencemag.org/news/2016/03/milky-way-s-black-hole-may-be-spewing-out-cosmic-rays

 

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Draggendrop    5,747

VLA shows earliest stages of planet formation

 

oozoomL_nrao.jpg

Planet formation             NRAO

 

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New images of a young star made with the Karl G. Jansky Very Large Array (VLA) reveal what scientists think may be the very earliest stages in the formation of planets. The scientists used the VLA to see unprecedented detail of the inner portion of a dusty disk surrounding the star, some 450 light-years from Earth.

 

The star and its disk were studied in 2014 with the Atacama Large Millimeter/submillimeter Array (ALMA), which produced what astronomers then called the best image ever of planet formation in progress. The ALMA image showed gaps in the disk, presumably caused by planet-like bodies sweeping out the dust along their orbits. This image, showing in real life what theorists had proposed for years, was surprising, however, because the star, called HL Tau, is only about a million years old -- very young by stellar standards.

 

The ALMA image showed details of the system in the outer portions of the disk, but in the inner portions of the disk, nearest to the young star, the thicker dust is opaque to the short radio wavelengths received by ALMA. To study this region, astronomers turned to the VLA, which receives longer wavelengths. Their VLA images show that region better than any previous studies.

 

The new VLA images revealed a distinct clump of dust in the inner region of the disk. The clump, the scientists said, contains roughly 3 to 8 times the mass of the Earth.

 

"We believe this clump of dust represents the earliest stage in the formation of protoplanets, and this is the first time we've seen that stage," said Thomas Henning, of the Max Planck Institute for Astronomy (MPIA).

http://www.eurekalert.org/pub_releases/2016-03/nrao-vse031716.php

 

http://spaceref.com/extrasolar-planets/vla-shows-earliest-stages-of-planet-formation.html

 

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Astronomers Discover Colossal 'Super Spiral' Galaxies

 

pia20064-16.jpg

In archived NASA data, researchers have discovered "super spiral" galaxies that dwarf our own spiral galaxy, the Milky Way, and compete in size and brightness with the largest galaxies in the universe. Image credit: SDSS

 

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Astronomers have identified 53 “super spirals” — spiral galaxies that are huge and incredibly luminous — as part of a project exploring archived observations.

The Milky Way is an average sort of spiral galaxy. Its disk spans roughly 100,000 light-years (although maybe more like 160,000 light-years, if recently detected, distant ripples are part of it). Each year it produces the equivalent of a Sun’s mass in new stars.

 

Although the Milky Way is one of the largest galaxies in the Local Group, across the cosmos the biggest, brightest galaxies are usually not spirals but ellipticals, gargantuan football-shaped collections of old stars.

 

But Patrick Ogle (Caltech) and his team have found 53 distant spirals that are bigger, brighter, and starbirthing-mightier than expected from their nearby spiral brethren. These newfound galaxies, which the team calls superlumious spirals or “super spirals” for short, have disks between 180,000 and 440,000 light-years wide, and they’re churning out stars at a rate of 5 to 65 Suns each year.

 

For galaxies this big and this late in cosmic history, that’s a lot of stars.

 

The team was sorting through the NASA/IPAC Extragalactic Database (a.k.a. “NED”) — a repository of observations, research papers, and other information (even includes a great glossary) — to see what kind of big-picture insights they could glean from its archive. They picked 1,616 galaxies out of NED that had redshifts less than 0.3 (meaning their light left them less than 3.5 billion years ago) and luminosities more than eight times that of the Milky Way. Through a process of “how much/what kind of data do we have on this galaxy” elimination, the team whittled down the group to a couple hundred and discovered that although the majority were ellipticals, 53 of these bright galaxies were super spirals.

 

No, that’s not a large number: these giants are clearly rare. In fact, they’re so rare in a given volume of space that cosmological simulations don’t operate on a large enough scale to produce many of them, meaning astronomers can’t use simulations to predict how many there should be or how they form.

 

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What’s interesting isn’t merely the galaxies’ size, but that they’re forming so many stars. Galaxies this massive would normally be well on the way to becoming “red and dead,” their stellar populations old and rosy. Somehow, super spirals managed not to choke off or heat up the cold gas supplies they need in order to make stars. The authors offer various theories for why that is, but the short answer is: we have no idea.

 

But we do know that there are dying, equally massive disk galaxies later on in the universe. These super spirals could be the precursors, the team suggests.

http://www.skyandtelescope.com/astronomy-news/super-spiral-galaxies-1803201623/

 

http://www.jpl.nasa.gov/news/news.php?feature=6149

 

http://arxiv.org/abs/1511.00659

 

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Astronomers found a star with a record variation period

 

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The Lomonosov Moscow State University astronomers who created a global network of robotelescopes MASTER detected that a bright star TYC 2505-672-1 has actually faded significantly. That finding induced new questions: so, the scientists assume that TYC 2505-672-1 is actually a double star system, though a nature of its companion remains unknown. The article was accepted to publication in Astronomy & Astrophysics, and is accessible as a pre-print at http://arxiv.org/abs/1602.06010

 

Three years ago a team of Russian scientists working with the global MASTER network of robotic telescopes spotted that the giant star in Leo minor with a catalogue number TYC 2505-672-1, which was considered to be extinct, in fact just faded -- its brightness decreased nearly 100 times.

 

Quote

Initially the discovery concerning the star's fading did not seem significant: phenomena of that kind may sometimes take place. However the question, why did the star become that dim, remained not answered. Diverge hypotheses were suggested, among which the most likely one seemed the idea that a red giant following its evolutionary processes emitted a cloud of stardust consisting of carbon particles and 'hid' itself from view.

 

Though, the later photometric measurements by MASTER-Amur and spectral measurements by the 6-metre BTA-6 telescope showed that the star did not turn red, as, for example, the Sun does before sunset (this happens because it takes longer for the sun rays to pierce the atmosphere). For that reason the star was tracked attentively, and soon it started to restore its luminosity. In October 2014 it recovered its normal shine level completely.

 

At approximately the same time Rolf Yansen, Dutch astronomer (Arizona university) draw attention to the star. He revised that data of Harvard observatory picture library, publicly available since June 2014, and suddenly detected that in 1942-1945 TYC 2505-672-1 underwent the same decrease in luminosity. According to the scientist's calculations, the star has an unprecedented variation period of 25245 days, which is about 69 years.

 

This fact means that a common star became a record-breaker in a length of variation period, absolutely out of a reach. According to Denis Denisenko, one of the discovery's authors, the longest known variation period used to belong to Epsilon Aurigae. Its eclipses repeat in 9890 days, which is a bit more than 27 years. Only five stars are known to have a period of more than ten years. In other words, the new variable star exceeds the existing record more than two and a half times.

http://www.eurekalert.org/pub_releases/2016-03/lmsu-afa031816.php

 

http://arxiv.org/abs/1602.06010

 

:)

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ctebah    3,161
On 3/13/2016 at 1:18 AM, Unobscured Vision said:

Well, well. That's certainly in line with what other observations are saying; and even the "size" of the Universe (40-something-odd billion light-years across) not jiving with the reputed age of the Universe (said to be 13.7~14.1 billion years) was a big problem. Now we're getting data that says that the CMB itself isn't what they thought it was before, and the age of the Universe (obviously) isn't what they thought it was either.

 

Good. Now the theories and hypotheses don't have to rely on non-relativistic functions, and they get to revise the age estimates more precisely when the new gear is available. I'll tell ya this much, folks -- that estimate is gonna be closer to the 20 billion year mark than people think if not past it.

 

I kinda figured something was up when HST was able to detect GN-z11 at a redshift of 11.1 when theoretically it shouldn't have been able to ... now we know why. :yes: 

 

Okay, HST -- you folks found yourselves an extended mission, for as long as the telescope and the WFP and NIR/UV components can hold out -- find as many r-11.0 and lower objects that you can, and start compiling the targets for JWST. That one needs them.

 

I'd really like to see one more Servicing Mission to HST once the Manned Dragon program is up and running. HST is proving to have some Science Value left in it, but it needs a refill on the coolant and maybe some servicing. Nothing major yet. 

That's amazing.  We are lucky to be living at a time when space based observatories, as well as ground based one, are getting larger and larger.  I can't wait for JWST and the huge ground based telescopes to fire up.

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Draggendrop    5,747

Caught For The First Time: The Early Flash Of An Exploding Star

 

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The brilliant flash of an exploding star’s shockwave—what astronomers call the “shock breakout”—has been captured for the first time in the optical wavelength or visible light by NASA's planet-hunter, the Kepler space telescope.

An international science team led by Peter Garnavich, an astrophysics professor at the University of Notre Dame in Indiana, analyzed light captured by Kepler every 30 minutes over a three-year period from 500 distant galaxies, searching some 50 trillion stars. They were hunting for signs of massive stellar death explosions known as supernovae.

 

breakout_sim-ws_v6.png

The diagram illustrates the brightness of a supernova event relative to the sun as it unfolds. For the first time, a supernova shockwave has been observed in the optical wavelength or visible light as it reaches the surface of the star. This early flash of light is called a shock breakout. The explosive death of this star, called KSN 2011d, as it reaches its maximum brightness takes 14 days. The shock breakout itself lasts only about 20 minutes, so catching the flash of energy is an investigative milestone for astronomers. The unceasing gaze of NASA's Kepler space telescope allowed astronomers to see, at last, this early moment as the star blows itself to bits. Supernovae like these — known as Type II — begin when the internal furnace of a star runs out of nuclear fuel causing its core to collapse as gravity takes over. This type of star is called a red supergiant star and it is 20,000 times brighter than our sun. As the supergiant star goes supernova, the energy traveling from the core reaches the surfaces with a burst of light that is 130,000,000 times brighter than the sun. The star continues to explode and grow reaching maximum brightness that is about 1,000,000,000 times brighter than the sun.
Credits: NASA Ames/W. Stenzel

 

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In 2011, two of these massive stars, called red supergiants, exploded while in Kepler’s view. The first behemoth, KSN 2011a, is nearly 300 times the size of our sun and a mere 700 million light years from Earth. The second, KSN 2011d, is roughly 500 times the size of our sun and around 1.2 billion light years away.

 

“To put their size into perspective, Earth's orbit about our sun would fit comfortably within these colossal stars,” said Garnavich.

 

Whether it’s a plane crash, car wreck or supernova, capturing images of sudden, catastrophic events is extremely difficult but tremendously helpful in understanding root cause. Just as widespread deployment of mobile cameras has made forensic videos more common, the steady gaze of Kepler allowed astronomers to see, at last, a supernova shockwave as it reached the surface of a star. The shock breakout itself lasts only about 20 minutes, so catching the flash of energy is an investigative milestone for astronomers.

 

“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler's vigilance allowed us to be a witness as the explosion began.”

Supernovae like these — known as Type II — begin when the internal furnace of a star runs out of nuclear fuel causing its core to collapse as gravity takes over.

 

The two supernovae matched up well with mathematical models of Type II explosions reinforcing existing theories. But they also revealed what could turn out to be an unexpected variety in the individual details of these cataclysmic stellar events.

 

While both explosions delivered a similar energetic punch, no shock breakout was seen in the smaller of the supergiants. Scientists think that is likely due to the smaller star being surrounded by gas, perhaps enough to mask the shockwave when it reached the star's surface.

 

“That is the puzzle of these results,” said Garnavich. “You look at two supernovae and see two different things. That’s maximum diversity.”

Understanding the physics of these violent events allows scientists to better understand how the seeds of chemical complexity and life itself have been scattered in space and time in our Milky Way galaxy

 

"All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars," said Steve Howell, project scientist for NASA's Kepler and K2 missions at NASA’s Ames Research Center in California's Silicon Valley. "Life exists because of supernovae."

 

Garnavich is part of a research team known as the Kepler Extragalactic Survey or KEGS. The team is nearly finished mining data from Kepler’s primary mission, which ended in 2013 with the failure of reaction wheels that helped keep the spacecraft steady. However, with the reboot of the Kepler spacecraft as NASA's K2 mission, the team is now combing through more data hunting for supernova events in even more galaxies far, far away.

 

"While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open observing dozens more supernovae," said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. "These results are a tantalizing preamble to what's to come from K2!"

 

In addition to Notre Dame, the KEGS team also includes researchers from the University of Maryland in College Park; the Australian National University in Canberra, Australia; the Space Telescope Science Institute in Baltimore, Maryland; and the University of California, Berkeley.

http://www.nasa.gov/feature/ames/Kepler/caught-for-the-first-time-the-early-flash-of-an-exploding-star

 

Research paper

Shock Breakout and Early Light Curves of Type II-P Supernovae Observed with Kepler

http://arxiv.org/abs/1603.05657

 

Caught for the First Time: The Early Flash of an Exploding Star

video is 0:29 min.

 

 

 

:)

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Unobscured Vision    2,676

Oooh, they've been looking for that for a while. :yes: I wonder how long it takes for that breakout to reach the outer layer of the star once the "big implosion" happens?

 

See, we know that a Supernova happens because the star in question tries to burn through Iron, and can't because Iron isn't a fuseable element (it takes more energy to fuse it than the fusion produces), so that stellar equilibrium of outward pressure no longer is able to support the mass of the star, and it collapses in on itself causing the Supernova.

 

The thing is, Science says that it takes all of that energy produced in a stars' core something on the order of 1,000~100,000 years to escape the star; I'm just curious if the breakout happens instantly or if it takes time to break free, like a "domino effect". Seems to me it can't happen instantaneously; no matter how much energy it's releasing, it still has to obey physics -- including the speed of light -- and if there's matter in the way it'll slow that breakout down a bit. Yes, the star is a "dead man walking"; but it's still got to obey the speed of light and physics and a star as large and massive as those are tend to be several light-minutes across. They're dead and alive at the same time!

 

Bit of a fun think, isn't it? :D 

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Unobscured Vision    2,676

Oh, and furthermore, because stars that are doing that are usually massive enough to form either a Neutron Star or a Black Hole, we now get into the realm of Time Dilation effects. Welcome to the land of high strangeness!

 

Think of it ...

 

I purport that as the star is collapsing (the matter is falling into a central location), time begins to move ever more slowly. We've got our Supernova alright, forming super-heavy elements in ever-increasing amounts .... more and more, brighter and brighter, slower and slower, until ....

 

The watch hands stop turning. That critical threshold. Anything outside of it is free to go about its' merry way. Anything within that threshold simply "stops".

 

Black holes aren't "black" because they aren't there anymore ... they're "black" because time has stopped in that area due to the gravity being so high. Light can't escape because it doesn't know that it got trapped too, like a painting.

 

There's no escape. Time will never move forward again in that region. Ever. It's a great place to store something forever, though; unchanging, immutable.

 

Anyway, I purport that the longer the supernova lasts, the smaller (less massive) the star that caused it will be. Larger (more massive) stars will "black hole" much more quickly, and thus the time will be shortened.

 

*bow*

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Draggendrop    5,747

NASA marks major milestones for the James Webb Space Telescope

 

111579_web.jpg

 

Quote
CAPTION
NASA's James Webb Space Telescope completed primary mirror sits in the cleanroom at NASA Goddard Space Flight Center, and supported over it on the tripod is the secondary mirror.
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http://www.eurekalert.org/multimedia/pub/111579.php

 

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NASA's James Webb Space Telescope just got a little closer to launch with the completion of cryogenic testing on its science cameras and spectrographs and the installation of the final flight mirrors.

 

After over a year of planning, nearly four months of final cryo (cold) testing and monitoring, the testing on the science instruments module of the observatory was completed. They were removed from a giant thermal vacuum chamber at NASA's Goddard Space Flight Center in Greenbelt, Maryland called the Space Environment Simulator, or SES, that duplicates the vacuum and extreme temperatures of space. The SES is a 40-foot-tall, 27-foot-diameter cylindrical chamber that eliminates almost all of the air with vacuum pumps and uses liquid nitrogen and even colder gaseous helium to drop the temperature.

 

"We needed to test these instruments against the cold because one of the more difficult things on this project is that we are operating at very cold temperatures," said Begona Vila, NASA's Cryogenic Test Lead for the ISIM at NASA Goddard. The ISIM, or Integrated Science Instrument Module is one of three major elements that comprise the James Webb Space Telescope Observatory flight system. "We needed to make sure everything moves and behaves the way we expect them to in space. Everything has to be very precisely aligned for the cameras to take their measurements at those cold temperatures which they are optimized for."

 

The testing is critical because at these instrument's final destination in space, one million miles away from Earth, it will operate at incredibly cold temperatures of minus 387 degrees Fahrenheit, or 40 degrees Kelvin. This is 260 degrees Fahrenheit colder than any place on the Earth's surface has ever been.

 

"This is the culmination of a lot of hard work by a lot of people who have been working for many, many years," said Jamie Dunn, NASA's Integrated Science Instrument Module Manager for the Webb telescope at Goddard. "This final test was phenomenal, everything is working spectacularly well.

more at the link...

http://www.spacedaily.com/reports/NASA_marks_major_milestones_for_the_James_Webb_Space_Telescope_999.html

 

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Tiny, ancient galaxy preserves record of catastrophic event

 

111526_web.jpg

CAPTION
This is an image of Reticulum II obtained by the Dark Energy Survey, using the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory. The nine stars described in the paper are circled in red. The insets show the very strong presence of barium, one of the main neutron capture elements the team observed, in three stars. Background image is courtesy of Dark Energy Survey/Fermilab. Foreground image is courtesy of Alexander Ji, Anna Frebel, Anirudh Chiti, and Josh Simon.
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The lightest few elements in the periodic table formed minutes after the Big Bang. Heavier chemical elements are created by stars, either from nuclear fusion in their interiors or in catastrophic explosions. However, scientists have disagreed for nearly 60 years about how the heaviest elements, such as gold and lead, are manufactured. New observations of a tiny galaxy discovered last year show that these heavy elements are likely left over from rare collisions between two neutron stars. The work is published by Nature.

 

The new galaxy, called Reticulum II because of its location in the southern constellation Reticulum, commonly known as The Net, is one of the smallest and closest to us known. Its proximity made it a tempting target for a team of astronomers including Carnegie's Josh Simon, who have been studying the chemical content of nearby galaxies.

 

"Reticulum II has more stars bright enough for chemical studies than any other ultra-faint dwarf galaxy found so far," Simon explained.

Such ultra-faint galaxies are relics from the era when the universe's first stars were born. They orbit our own Milky Way galaxy and their chemical simplicity can help astronomers understand the history of stellar processes dating back to the ancient universe, including element formation.

 

Many elements are formed by nuclear fusion, in which two atomic nuclei fuse together and release energy, creating a different, heavier atom. But elements heavier than zinc are made by a process called neutron capture, during which an existing element acquires additional neutrons one at a time that then "decay" into protons, changing the makeup of the atom into a new element.

 

Neutrons can be captured slowly, over long periods of time inside the star, or in a matter of seconds, when a catastrophic event causes a burst of neutrons to bombard an area. Different types of elements are created by each method.

 

Surprisingly, the team found that seven of Reticulum II's nine brightest stars contained far more elements produced by rapid neutron captures than have been detected in any other dwarf galaxy.

 

"These stars have up to a thousand times more neutron capture elements than any other stars observed in similar galaxies," said lead author Alexander Ji of the Massachusetts Institute of Technology.

 

Previously, astronomers had been divided over whether such elements are primarily made by supernova explosions or in more exotic cosmic locations, such as merging neutron stars. However, finding so many more heavy elements in one dwarf galaxy than had ever been seen before in others proves that the source of Reticulum II's neutron capture elements must have been a rare event - much less common than an ordinary supernova. What's more, the sheer amount of these neutron capture elements in Reticulum II far exceeds what most supernovae can even make.

"Producing rapid neutron capture elements in a neutron star merger explains these observations beautifully," said co-author Anna Frebel, also of MIT.

 

Old stars in the Milky Way show a pattern of neutron capture elements similar to that found in Reticulum II. This indicates that the process of making neutron capture elements in larger galaxies is likely the same as it is in dwarf galaxies, suggesting that even the heavy elements on Earth originated in neutron star mergers.

more at the link....

http://www.spacedaily.com/reports/Tiny_ancient_galaxy_preserves_record_of_catastrophic_event_999.html

 

Gotta love the periodic table and the exotic elements formed under high pressures and high temperatures....:D

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+Mirumir    5,635
45 minutes ago, Draggendrop said:

Tiny, ancient galaxy preserves record of catastrophic event

I think it's amazing how we can study the Cosmos right from our own backyard. We don't need to travel far away from Earth if we want to see how new stars and galaxies are formed or how they die.

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Draggendrop    5,747

With all the talk about pulsars, I thought that I would throw this video in...

 

An introduction to Pulsars - Pulsars and Quasars

video is 5:21 min.

 

 

 

-------------------

 

A new view of the X-ray sky

 

111805_web.jpg

This projection shows the sky distribution of 2RXS sources in Galactic coordinates. The size of each dot scales with the source count rate (brightness) and the color represents the X-ray color.
CREDIT
MPE

 

Quote

Scientists at the Max Planck Institute for Extraterrestrial Physics (MPE) have revisited the all-sky survey carried out by the ROSAT satellite, to create a new image of the sky in at X-ray wavelengths. Along with this a revised and extended version of the catalogue of bright and faint point-like sources will be released. The now published "2RXS catalogue" provides the deepest and cleanest X-ray all-sky survey to date, which will only be superseded with the launch of the next generation X-ray survey satellite, eROSITA, currently being completed at MPE.

 

In the 1990s, the ROSAT X-ray satellite performed the first deep all-sky survey with an imaging telescope in the 0.1-2.4 keV energy band, increasing the number of known X-ray sources by a factor of approximately 100. The intention of the new analysis was to improve the reliability of the catalogue, by re-analysing the original photon event files, using an advanced detection algorithm and a complete screening process.

 

An important feature of the new catalogue is a statistical assessment of the reliability of the sources. Because of the extreme sensitivity and low background of the ROSAT PSPC instrument, cosmic X-ray sources can be identified with the detection of just a few photons. These are sometimes difficult to distinguish from random fluctuations, and the new catalogue provides an assessment of this effect, based on simulated data.

 

The catalogue contains more than just a list of sources, for example X-ray images and overlaid X-ray contour lines for each of the detections are provided. For many sources, X-ray light curves were created to shows how the sources vary in brightness on intra-day timescales. For the brightest sources X-ray spectral fits were performed based on three basic spectral models, a power law, a thermal-plasma and a black-body emission model. This is important because it can distinguish what kind of cosmic source produces the X-rays. These include powerful accreting black holes, giant clusters of galaxies, active stars and the remnants of stars that exploded in supernova explosions.

 

With the new catalogue, the astrophysical community will now be able to explore these objects in the X-ray sky with more confidence, and with considerably more information.

 

Additionally, the experience gained by the high-energy group at MPE in creating the new ROSAT all-sky survey X-ray source catalogue will be integrated in the data reduction analysis and scientific exploration of the forthcoming eROSITA all-sky survey. The eROSITA X-ray survey telescope currently built by MPE will be launched in 2017 to scan the whole sky with even higher precision than ROSAT, reaching 30 times deeper into the universe. One of its main goals is to measure the distribution of about 100,000 galaxy clusters, containing thousands of galaxies each. The 2RXS catalogue is the deepest and most reliable X-ray all-sky survey before eROSITA.

Quote

Original publication:

Boller, Th., Freyberg, M., Trümper, J., Haberl, F., Voges, W., Nandra, K. 
Second ROSAT all-sky survey (2RXS) source catalogue 
A&A volume 588 (April 2016), id. A103 
Online publication March 24, 2016

 

http://www.eurekalert.org/pub_releases/2016-03/m-anv032416.php

 

--------------------------

 

Astrophysicists catch 2 supernovae at the moment of explosion

 

Quote

   
An international team of astrophysicists led by Peter Garnavich, professor of astrophysics at the University of Notre Dame, has caught two supernovae in the act of exploding. Using the Kepler Space Telescope, the team spent three years observing 50 trillion stars for the chance to watch as supersonic shockwaves reached their surfaces after explosions deep in the core. For the first time, a "shock breakout" in an exploding supergiant star was discovered at visible wavelengths.

 

Stars 10 to 20 times the mass of our sun often puff up to supergiants before ending their lives as supernovae. These stars are so large that the Earth's orbit would easily fit inside such a star. When these massive stars run out of fuel in their center, their core collapses down to a neutron star and a supersonic shockwave is sent out to blow up the entire star.

 

When the shockwave reaches the surface of the star, a bright flash of light, called a "shock breakout," is predicted.

"The flash from a breakout should last about an hour, so you have to be very lucky or continuously stare at millions of stars just to catch one flash," said Garnavich.

 

In 2011, two of these massive red supergiants exploded while in Kepler's view. The first, KSN 2011a, is nearly 300 times the size of our sun and a mere 700 million light years from Earth. The second, KSN 2011d, is roughly 500 times the size of our sun and some 1.2 billion light years away.

Supernovae like these - known as Type II - begin when the internal furnace of a star runs out of nuclear fuel causing its core to collapse as gravity takes over.

animation, 29 seconds.

Caught: A supernova shock breakout

 

 

 

http://www.spacedaily.com/reports/Astrophysicists_catch_2_supernovae_at_the_moment_of_explosion_999.html

 

---------------------

 

Magnetar could have boosted explosion of extremely bright supernova

 

111797_web.jpg

CAPTION
Artist impression of a magnetar boosting a super-luminous supernova and gamma-ray burst.
CREDIT
Kavli IPMU

 

Quote

Calculations by scientists have found highly magnetized, rapidly spinning neutron stars called magnetars could explain the energy source behind two extremely unusual stellar explosions.

 

Stellar explosions known as supernovae usually shine a billion times brighter than the Sun. Super-luminous supernovae (SLSNe) are a relatively new and rare class of stellar explosions, 10 to 100 times brighter than normal supernovae. But the energy source of their super-luminosity, and explosion mechanisms are a mystery and remain controversial amongst scientists.

 

A group of researchers led by Melina Bersten, an Instituto de Astrofisica de La Plata Researcher and affiliate member of Kavli IPMU, and including Kavli IPMU Principal Investigator Ken'ichi Nomoto, tested a model that suggests that the energy to power the luminosity of two recently discovered SLSNe, SN 2011kl and ASASSN-15lh, is mainly due to the rotational energy lost by a newly born magnetar. They analyzed two recently discovered super-luminous supernovae: SN 2011kl and ASASSN-15lh.

 

"These supernovae can be found in very distant universe, thus possibly informing us the properties of the first stars of the universe," said Nomoto.

Interestingly, both explosions were found to be extreme cases of SLSNe. First, SN 2011kl was discovered in 2011 and is the first supernovae to have an ultra long gamma-ray burst that lasted several hours, whereas typical long-duration gamma-ray bursts fade in a matter of minutes. The second, ASASSN-15lh, was discovered in 2015 and is possibly the most luminous and powerful explosion ever seen, more than 500 times brighter than normal supernovae. For more than a month its luminosity was 20 times brighter than the whole Milky Way galaxy.

 

The team performed numerical hydrodynamical calculations to explore the magnetar hypothesis, and found both SLSNe could be understood in the framework of magnetar-powered supernovae (see image 1). In particular, for ASASSN-15lh, they were able to find a magnetar source with physically allowed properties of magnetic field strength and rotation period. The solution avoided the prohibited realm of neutro-star spins that would cause the object to breakup due to centrifugal forces.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/kift-mch032416.php

 

:)

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Draggendrop    5,747

Most 'outrageously' luminous galaxies ever observed

 

111674_web.jpg

The 50-meter diameter Large Millimeter Telescope is the largest, most sensitive single-aperture instrument in the world for studying star formation. Operated jointly by UMass Amherst and Mexico's Instituto Nacional de Astrofísica, Óptica y Electrónica, it was recently used to observe the most luminous galaxies ever seen.
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Astronomers at the University of Massachusetts Amherst report that they have observed the most luminous galaxies ever seen in the Universe, objects so bright that established descriptors such as "ultra-" and "hyper-luminous" used to describe previously brightest known galaxies don't even come close. Lead author and undergraduate Kevin Harrington says, "We've taken to calling them 'outrageously luminous' among ourselves, because there is no scientific term to apply."

 

Details appear in the current early online edition of Monthly Notices of the Royal Astronomical Society.

 

Harrington is a senior undergraduate in astronomy professor Min Yun's group, which uses the 50-meter diameter Large Millimeter Telescope (LMT), the largest, most sensitive single-aperture instrument in the world for studying star formation. It is operated jointly by UMass Amherst and Mexico's Instituto Nacional de Astrofisica, Optica y Electronica and is located on the summit of Sierra Negra, a 15,000-foot extinct volcano in the central state of Puebla, a companion peak to Mexico's highest mountain.

 

Yun, Harrington and colleagues also used the latest generation of satellite telescope and a cosmology experiment on the NASA/ESA collaboration Planck satellite that detects the glow of the Big Bang and microwave background for this work. They estimate that the newly observed galaxies they identified are about 10 billion years old and were formed only about 4 billion years after the Big Bang.

 

Harrington explains that in categorizing luminous sources, astronomers call an infrared galaxy "ultra-luminous" when it has a rating of about 1 trillion solar luminosities, and that rises to about 10 trillion solar luminosities at the "hyper-luminous" level. Beyond that, for the 100 trillion solar luminosities range of the new objects, "we don't even have a name," he says.

 

Yun adds, "The galaxies we found were not predicted by theory to exist; they're too big and too bright, so no one really looked for them before." Discovering them will help astronomers understand more about the early Universe. "Knowing that they really do exist and how much they have grown in the first 4 billion years since the Big Bang helps us estimate how much material was there for them to work with. Their existence teaches us about the process of collecting matter and of galaxy formation. They suggest that this process is more complex than many people thought."

 

The newly observed galaxies are not as large as they appear, the researchers point out. Follow-up studies suggest that their extreme brightness arises from a phenomenon called gravitational lensing that magnifies light passing near massive objects, as predicted by Einstein's general relativity. As a result, from Earth they look about 10 times brighter than they really are. Even so, they are impressive, Yun says.

 

Gravitational lensing of a distant galaxy by another galaxy is quite rare, he adds, so finding as many as eight potential lensed objects as part of this investigation "is another potentially important discovery." Harrington points out that discovering gravitational lensing is already like finding a needle in a haystack, because it requires a precise alignment from viewing on Earth. "On top of that, finding lensed sources this bright is as rare as finding the hole in the needle in the haystack."

more at the link...

http://www.spacedaily.com/reports/Amherst_astronomers_report_most_outrageously_luminous_galaxies_ever_observed_999.html

 

:D

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Draggendrop    5,747

New research shows quasars slowed star formation

 

111739_web.jpg

In an artist's conception, heated galactic wind shown in the hazy portion of the picture emanates from the bright quasar at the edge of a black hole, scattering dust and gas. If allowed to cool and condense, that dust and gas would instead begin to form stars.
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Research led by Johns Hopkins University scientists has found new persuasive evidence that could help solve a longstanding mystery in astrophysics: Why did the pace of star formation in the universe slow down some 11 billion years ago?

 

A paper published in the Monthly Notices of the Royal Astronomical Society finds evidence supporting the argument that the answer was energy feedback from quasars within the galaxies where stars are born. That is, intense radiation and galaxy-scale winds emitted by the quasars - the most luminous objects in the universe - heats up clouds of dust and gas. The heat prevents that material from cooling and forming more dense clouds, and eventually stars.

 

"I would argue that this is the first convincing observational evidence of the presence of quasar feedback when the universe was only a quarter of its present age, when the cosmic star formation was most vigorous," said Tobias Marriage, an assistant professor in the university's Henry A. Rowland Department of Physics and Astronomy. While the findings appearing in the journal published by the Oxford University Press are not conclusive, Marriage said, the evidence is very compelling and has scientists excited.

 

"It's like finding a smoking gun with fingerprints near the body, but not finding the bullet to match the gun," Marriage said.

 

Specifically, investigators looked at information on 17,468 galaxies and found a tracer of energy known as the Sunyaev-Zel'dovich Effect. The phenomenon, named for two Russian physicists who predicted it nearly 50 years ago, appears when high-energy electrons disturb the Cosmic Microwave Background. The CMB is a pervasive sea of microwave radiation, a remnant from the superheated birth of the universe some 13.7 billion years ago.

 

Devin Crichton, a Johns Hopkins graduate student and the paper's lead author, said the thermal energy levels were analyzed to see if they rise above predictions for what it would take to stop star formation. A large number of galaxies were studied to give the study statistical heft, he said.

"For feedback to turn off star formation, it must be occurring broadly," said Crichton, one of five Johns Hopkins scientists who led the work conducted by a total of 23 investigators from 18 institutions. Most of the scientists are members of the Atacama Cosmology Telescope collaboration, named for one of the three instruments used in the study.

 

To take the faint temperature measurements that would show the Sunyaev-Zel'dovich Effect, the scientists used information gathered by two ground-based telescopes and one receiver mounted on a space observatory. Using several instruments with different strengths in search of the SZ Effect is relatively new, Marriage said.

 

"It's a pretty wild sort of thermometer," he said.

 

Information gathered in the Sloan Digital Sky Survey by an optical telescope at the Apache Point Observatory in New Mexico was used to find the quasars. Thermal energy and evidence of the SZ Effect were found using information from the Atacama Cosmology Telescope, an instrument designed to study the CMB that stands in the Atacama Desert in northern Chile. To focus on the dust, investigators used data from the SPIRE, or Spectral and Photometric Imaging Receiver, on the Herschel Space Observatory.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/jhu-nrs032316.php

 

Paper

http://mnras.oxfordjournals.org/content/458/2/1478.full?sid=da388dda-a51d-4133-8aad-8bdeb904a9d5

 

similar article

New research shows quasars slowed star formation

http://www.spacedaily.com/reports/New_research_shows_quasars_slowed_star_formation_999.html

 

 

//

generic Quasar definition

 

Quote

Quasars (/ˈkweɪzɑːr/) or quasi-stellar radio sources are the most energetic and distant members of a class of objects called active galactic nuclei (AGN). Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that appeared to be similar to stars, rather than extended sources similar to galaxies. Their spectra contain very broad emission lines, unlike any known from stars, hence the name "quasi-stellar." Their luminosity can be 100 times greater than that of the Milky Way.[2] Most quasars were formed approximately 12 billion years ago, and they are normally caused by collisions of galaxies, with the galaxies' central black holes merging to form either a supermassive black hole[3] or a binary black hole system.

Although the true nature of these objects was controversial until the early 1980s, there is now a scientific consensus that a quasar is a compact region in the center of a massive galaxy surrounding a central supermassive black hole.[4] Its size is 10–10,000 times the Schwarzschild radius of the enclosed black hole. The energy emitted by a quasar derives from mass falling onto the accretion disc around the black hole.

https://en.wikipedia.org/wiki/Quasar

 

:)

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Draggendrop    5,747

Students map Milky Way with dwarf stars

 

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Two astronomy students from Leiden University have mapped the entire Milky Way galaxy in dwarf stars for the first time. They show that there are a total of 58 billion dwarf stars, of which seven per cent reside in the outer regions of our Galaxy. This result is the most comprehensive model ever for the distribution of these stars. The findings appear in a new paper in Monthly Notices of the Royal Astronomical Society.

 

The Milky Way, the galaxy we live in, consists of a prominent, relatively flat disc with closely spaced bright stars, and a halo, a sphere of stars with a much lower density around it. Astronomers assume that the halo is the remnant of the first galaxies that fused together to form our Galaxy.


To find out exactly what the Milky Way looks like, astronomers have previously made maps using counts of the stars in the night sky. Leiden Astronomy students Isabel van Vledder and Dieuwertje van der Vlugt used the same technique in their research. Rather than studying bright stars, the two students used Hubble Space Telescope data from 274 dwarf stars, which were serendipitously observed by the orbiting observatory while it was looking for the most distant galaxies in the early Universe. The particular type of star they looked at were red dwarfs of spectral class M.

 

Dwarf stars are undersized and often have too low a mass to burn hydrogen. As warm, rather than hot objects, they are best viewed with near-infrared cameras. Van Vledder comments: "Astronomers believe that there are very many of these stars. That makes them really quite suitable for mapping the Galaxy even though they are so hard to find."


To find the distribution of the M dwarfs, Van Vledder and Van der Vlugt used three density models that astronomers use to describe the flat disc and halo, both separately and combined. To calculate which model best describes the structure of the Milky Way; the students then applied the Markov Chain Monte Carlo method. Van der Vlugt describes how this works: "You let a computer program test all possible values of each parameter of your model. It then fixes the value which corresponds best with the data."


The model that includes both disk and halo was the perfect match. From the positions of the 274 M dwarfs in their sample, van Vledder and van der Vlugt inferred the existence of 58 billion dwarf stars. They were also able to accurately estimate the number of dwarfs in the halo, calculating a fraction of 7 per cent, higher than astronomers have previously found for the whole Milky Way.


The results of the students are important for future research with the European Space Agency’s Euclid Space Telescope, due for launch in 2020. Like Hubble, Euclid will image the whole sky in near-infrared. Van Vledder adds: "With our research, astronomers can now better assess whether they are dealing with a distant galaxy or a star in our own Galaxy." The students expect Euclid observations to yield an even more accurate picture of the Milky Way.

 

M%20dwarf%20Milky%20Way%20map.jpg

Fields observed by the Hubble Space Telescope where M-dwarf stars have been found, plotted on a map of the sky with galactic longitude and latitude. In each field, indicated by circles, only a few dwarf stars are identified. However, by combining them, the students could derive an accurate model of the Galaxy. Credit: Leiden Observatory.

 

 

2mass_allskyatlas.jpg

The Milky Way in the 2MASS infrared survey, similar to Hubble observations of the sky colour (near-infrared). Here, the visible stars are mostly bright giant stars. Credit: The Infrared Processing and Analysis Center (IPAC) http://www.ipac.caltech.edu/2mass/gallery/2mass_allskyatlas.jpg.

 

https://www.ras.org.uk/news-and-press/2807-students-map-milky-way-with-dwarf-stars

 

http://www.space.com/32399-galaxy-map-here-are-the-milky-way-s-red-dwarfs.html

 

:)

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Jim K    13,620

Instruments final cryo test before installation.

 

 

 

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Draggendrop    5,747

Herschel Reveals a Ribbon of Future Stars

 

ooHerschel_reveals.jpg

Cold cloud filament G82.65-2.00                     ESA/HERSCHEL/SPIRE/M. JUVELA (U. HELSINKI, FINLAND)

 

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Star formation is taking place all around us. The Milky Way is laced with clouds of dust and gas that could become the nursery of the next generation of stars

 

Thanks to ESA's Herschel space observatory, we can now look inside these clouds and see what is truly going on.

 

It may seem ironic but when searching for sites of future star formation, astronomers look for the coldest spots in the Milky Way. This is because before the stars ignite the gas that will form their bulk must collapse together. To do that, it has to be cold and sluggish, so that it cannot resist gravity.

 

As well as gas, there is also dust. This too is extremely cold, perhaps just 1020 degrees above absolute zero. To optical telescopes it appears completely dark, but the dust reveals itself at far-infrared wavelengths.

 

One of the surprises is that the coldest parts of the cloud form filaments that stretch across the warmer parts of the cloud. This image shows a cold cloud filament, known to astronomers as G82.65-2.00. The blue filament is the coldest part of the cloud and contains 800 times as much mass as the Sun. The dust in this filament has a temperature of 259C. At this low temperature, if the filament contains enough mass it is likely that this section will collapse into stars.

 

This image is colour-coded so that the longest infrared wavelength, corresponding to the coldest region, is shown in blue, and the shortest wavelength, corresponding to slightly warmer dust, is shown in red.

http://spaceref.com/astronomy/herschel-reveals-a-ribbon-of-future-stars.html

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Unobscured Vision    2,676

Makes sense. Cold = dense, warm = less dense.

 

There's something to learn here, Fusion Scientists. :yes: 

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Draggendrop    5,747

In reference to the above post...

Herschel Reveals a Ribbon of Future Stars

 

This is similar to Elon's tweet..."counter intuitive"

 

The cold ribbons are the locations to catch "stars" before they are created (when gravity overpowers thermal energy), hence it being ironic to look there, when warmer molecular clouds create stars of all masses. The cooler area's are of interest due to density of gas and dust and the ability to concentrate searches there...but the type of molecular cloud and the reference temperature for the structure, will play the largest role in the stars development. In reference to one another, a "cooler" molecular cloud will tend to form "low mass" stars, while warmer ones  form "all masses".

 

https://en.wikipedia.org/wiki/Star_formation

 

as a side note, IMHO, fusion power is not a big deal at the moment due to liquid salt reactor work (LFTR's) being carried out and solely financed by the Chinese and working in co-operation with a large multinational, multi branch, science force. Everyone is hoping that a first generation (high efficiency) commercial unit  will appear in approximately 10 years (The urgency has to do with severe pollution problems), where upon, fusion can then take the focus for another 50 years and no one will really miss it much. 

Fusion power has the problem of not having the "affordable technology" to do what one wants to do now, so we can wait until available, thanks to LFTR's.

 

:)

 

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Simulating supermassive black holes

 

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Simulation of a network of dark matter filaments in a high-density region of the early universe. Each dense bright spot is a dark matter halo into which gas collapses to form large galaxies and supermassive black holes.
CREDIT
2015 Kentaro Nagamine, Osaka University
USAGE RESTRICTIONS
None

 

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Near the edge of the visible Universe are some of the brightest objects ever observed, known as quasars, which are believed to contain supermassive black holes of more than a billion times the mass of our Sun. Simulations by Kentaro Nagamine at Osaka University's Department of Earth and Space Science, Isaac Shlosman at the University of Kentucky and co-workers have revealed for the first time exactly how these black holes formed 700 million years after the Big Bang.

 

"The early Universe was a dense, hot and uniform plasma," explains Nagamine. "As it cooled, fluctuations in the mass distribution formed seeds around which matter could gather due to gravity." These are the origins of the first stars. Similar processes might have later seeded the growth of bigger structures such as supermassive black holes.

 

Until recently, many researchers thought supermassive black holes were seeded by the collapse of some of the first stars. But modeling work by several groups has suggested that this process would only lead to small black holes. Nagamine and co-workers simulated a different situation, in which supermassive black holes are seeded by clouds of gas falling into potential wells created by dark matter -- the invisible matter that astronomers believe makes up 85% of the mass of the Universe.

 

Simulating the dynamics of huge gas clouds is extremely complex, so the team had to use some numerical tricks called 'sink particles' to simplify the problem.

 

"Although we have access to extremely powerful supercomputers at Osaka University's Cybermedia Center and the National Astronomical Observatory of Japan, we can't simulate every single gas particle," explains Nagamine. "Instead, we model small spatial scales using sink particles, which grow as the surrounding gas evolves. This allows us to simulate much longer timescales than was previously possible."

 

The researchers found that most seed particles in their simulations did not grow very much, except for one central seed, which grew rapidly to more than 2 million Sun-masses in just 2 million years, representing a feasible path toward a supermassive black hole. Moreover, as the gas spun and collapsed around the central seed it formed two misaligned accretion discs, which have never been observed before.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/ou-ssb033016.php

 

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Earth-space telescope system produces hot surprise

 

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Artistic view of the 10-meter space radio telescope on board of the Russian satellite Spektr-R comprising the space-borne component of the RadioAstron mission. Image courtesy Astro Space Center of Lebedev Physical Institute.

 

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Astronomers using an orbiting radio telescope in conjunction with four ground-based radio telescopes have achieved the highest resolution, or ability to discern fine detail, of any astronomical observation ever made. Their achievement produced a pair of scientific surprises that promise to advance the understanding of quasars, supermassive black holes at the cores of galaxies.

 

The scientists combined the Russian RadioAstron satellite with the ground-based telescopes to produce a virtual radio telescope more than 100,000 miles across. They pointed this system at a quasar called 3C 273, more than 2 billion light-years from Earth. Quasars like 3C 273 propel huge jets of material outward at speeds nearly that of light. These powerful jets emit radio waves.

 

Just how bright such emission could be, however, was thought to be limited by physical processes. That limit, scientists thought, was about 100 billion degrees. The researchers were surprised when their Earth-space system revealed a temperature hotter then 10 trillion degrees.

 

"Only this space-Earth system could reveal this temperature, and now we have to figure out how that environment can reach such temperatures," said Yuri Kovalev, the RadioAstron project scientist. "This result is a significant challenge to our current understanding of quasar jets," he added.

The observations also showed, for the first time, substructure caused by scattering of the radio waves by the tenuous interstellar material in our own Milky Way Galaxy.

 

"This is like looking through the hot, turbulent air above a candle flame," said Michael Johnson, of the Harvard-Smithsonian Center for Astrophysics. "We had never been able to see such distortion of an extragalactic object before," he added.

 

"The amazing resolution we get from RadioAstron working with the ground-based telescopes gives us a powerful new tool to explore not only the extreme physics near the distant supermassive black holes, but also the diffuse material in our home Galaxy," Johnson said.

 

The RadioAstron satellite was combined with the Green Bank Telescope in West Virginia, The Very Large Array in New Mexico, the Effelsberg Telescope in Germany, and the Arecibo Observatory in Puerto Rico. Signals received by the orbiting radio telescope were transmitted to an antenna in Green Bank where they were recorded and then sent over the internet to Russia where they were combined with the data received by the ground-based radio telescopes to form the high resolution image of 3C 273.

 

The astronomers reported their results in the Astrophysical Journal Letters.

 

In 1963, astronomer Maarten Schmidt of Caltech recognized that a visible-light spectrum of 3C 273 indicated its great distance, resolving what had been a mystery about quasars. His discovery showed that the objects are emitting tremendous amounts of energy and led to the current model of powerful emission driven by the tremendous gravitational energy of a supermassive black hole.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/nrao-ats032916.php

 

http://www.spacedaily.com/reports/RadioAstron_Observations_of_the_Extremely_Hot_Heart_of_Quasar_3C_273_999.html

 

:D

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Draggendrop    5,747

ALMA's most detailed image of a protoplanetary disc

 

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ALMA's best image of a protoplanetary disc to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets are in formation in this system.
CREDIT
S. Andrews (Harvard-Smithsonian CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)
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None

 

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The star TW Hydrae is a popular target of study for astronomers because of its proximity to Earth (only about 175 light-years away) and its status as an infant star (about 10 million years old). It also has a face-on orientation as seen from Earth. This gives astronomers a rare, undistorted view of the complete protoplanetary disc around the star.

 

"Previous studies with optical and radio telescopes confirm that TW Hydrae hosts a prominent disc with features that strongly suggest planets are beginning to coalesce," said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, USA and lead author on a paper published today in the Astrophysical Journal Letters. "The new ALMA images show the disc in unprecedented detail, revealing a series of concentric dusty bright rings and dark gaps, including intriguing features that may indicate that a planet with an Earth-like orbit is forming there."

 

Other pronounced gaps that show up in the new images are located three billion and six billion kilometres from the central star, similar to the average distances from the Sun to Uranus and Pluto in the Solar System. They too are likely to be the results of particles that came together to form planets, which then swept their orbits clear of dust and gas and shepherded the remaining material into well-defined bands.

 

For the new TW Hydrae observations, astronomers imaged the faint radio emission from millimetre-sized dust grains in the disc, revealing details on the order of the distance between the Earth and the Sun (about 150 million kilometres). These detailed observations were made possible with ALMA 's high-resolution, long-baseline configuration. When ALMA's dishes are at their maximum separation, up to 15 kilometres apart, the telescope is able to resolve finer details. "This is the highest spatial resolution image ever of a protoplanetary disc from ALMA, and that won't be easily beaten in the future!" said Andrews [1].

 

"TW Hydrae is quite special. It is the nearest known protoplanetary disc to Earth and it may closely resemble the Solar System when it was only 10 million years old," adds co-author David Wilner, also with the Harvard-Smithsonian Center for Astrophysics.

more at the link...

http://www.eurekalert.org/pub_releases/2016-03/e-amd033116.php

 

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White dwarf star exhibits an unusual atmosphere of oxygen

 

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Researchers have discovered a white dwarf star with an atmosphere dominated by oxygen, a type of white dwarf that has been theorized to exist but not identified to date. The finding could challenge the textbook wisdom of single stellar evolution, and provide a critical link to some types of supernovae discovered over the past decade.

 

As relatively small stars (those less than ten times the mass of our sun) near the end of their lives, they throw off their outer layers and become white dwarf stars, which are very dense. The high gravity that occurs under such density causes the lighter elements, such as hydrogen or helium, to float to the surface of the star, masking the heavier elements below.

 

While combing through data from the Sloan Digital Sky Survey (SDSS), Souza Oliveira Kepler et al. identified SDSS J124043.01+671034.68, a white dwarf with its outer layer of light elements stripped away, revealing a nearly pure layer of oxygen. Several different theories have predicted that the outer layer of a white dwarf can be stripped, but identification of ­­­ SDSS J124043.01+671034.68 provides the first evidence of this phenomenon.

 

One possibility is that interactions with a nearby companion in a binary star caused SDSS J124043.01+671034.68 to bare its oxygen envelope.

 

Another possibility is that a massive pulse of burning carbon from the center of the star, emulating outwards, eliminated the lighter elements. A Perspective by Boris Gänsicke provides further context.

http://www.eurekalert.org/pub_releases/2016-03/aaft-wds032816.php

 

http://science.sciencemag.org/content/352/6281/67

 

:)

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Draggendrop    5,747

Trigger for Milky Way’s Youngest Supernova Identified

 

g19.jpg?itok=D3umlowZ

Scientists have used data from NASA’s Chandra X-ray Observatory and the NSF’s Jansky Very Large Array to determine the likely trigger for the most recent supernova in the Milky Way, as described in our latest feature.

Image credit: NASA/CXC/CfA/S. Chakraborti et al.

 

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Scientists have used data from NASA’s Chandra X-ray Observatory and the NSF’s Jansky Very Large Array to determine the likely trigger for the most recent supernova in the Milky Way. They applied a new technique that could have implications for understanding other Type Ia supernovas, a class of stellar explosions that scientists use to determine the expansion rate of the Universe.

 

Astronomers had previously identified G1.9+0.3 as the remnant of the most recent supernova in our Galaxy. It is estimated to have occurred about 110 years ago in a dusty region of the Galaxy that blocked visible light from reaching Earth.

 

G1.9+0.3 belongs to the Type Ia category, an important class of supernovas exhibiting reliable patterns in their brightness that make them valuable tools for measuring the rate at which the universe is expanding.

 

“Astronomers use Type Ia supernovas as distance markers across the Universe, which helped us discover that its expansion was accelerating,” said Sayan Chakraborti, who led the study at Harvard University. “If there are any differences in how these supernovas explode and the amount of light they produce, that could have an impact on our understanding of this expansion.”

 

Most scientists agree that Type Ia supernovas occur when white dwarfs, the dense remnants of Sun-like stars that have run out of fuel, explode.

 

However, there has been a debate over what triggers these white dwarf explosions. Two primary ideas are the accumulation of material onto a white dwarf from a companion star or the violent merger of two white dwarfs.

 

The new research with archival Chandra and VLA data examines how the expanding supernova remnant G1.0+0.3 interacts with the gas and dust surrounding the explosion. The resulting radio and X-ray emission provide clues as to the cause of the explosion. In particular, an increase in X-ray and radio brightness of the supernova remnant with time, according to theoretical work by Chakraborti’s team, is expected only if a white dwarf merger took place.

 

“We observed that the X-ray and radio brightness increased with time, so the data point strongly to a collision between two white dwarfs as being the trigger for the supernova explosion in G1.9+0.3,” said co-author Francesca Childs, also of Harvard.

 

The result implies that Type Ia supernovas are either all caused by white dwarf collisions, or are caused by a mixture of white dwarf collisions and the mechanism where the white dwarf pulls material from a companion star.

 

“It is important to identify the trigger mechanism for Type Ia supernovas because if there is more than one cause, then the contribution from each may change over time,” said Harvard’s Alicia Soderberg, another co-author on the study. This means astronomers might have to recalibrate some of the ways we use them as ‘standard candles’ in cosmology.”

 

The team also derived a new estimate for the age of the supernova remnant of about 110 years, younger than previous estimates of about 150 years.

https://www.nasa.gov/mission_pages/chandra/trigger-for-milky-way-s-youngest-supernova-identified.html

 

http://www.spacedaily.com/reports/Trigger_for_Milky_Ways_Youngest_Supernova_Identified_999.html

 

paper...

http://arxiv.org/abs/1510.08851

 

:D

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T3X4S    4,532

This is boring - we need news from the other universe(s) - 


:)

 

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Draggendrop    5,747
Just now, T3X4S said:

This is boring - we need news from the other universe(s) - 


:)

 

I'm on it.....sorry....:woot:

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LOC    1,109
11 hours ago, T3X4S said:

This is boring - we need news from the other universe(s) - 


:)

 

That's funny you said that. On my Android tablet I use SmartNews (a really good news aggregator app, highly recommended btw) and there was a PopSci article a few days ago I think (maybe from last year source wise though) basically talking about the multiverse etc. One of the best stories from a fun perspective, was that our universe, is literally a holographic simulation and we are all computer algorithms in some higher beings system in a higher dimensional universe. But that because their technology is so advanced, we are literally our own universe not just a simulation itself, and we can MAKE our own universes and my mind started getting blown away at that point.

 

Plus, I studied physics in college, quantum dynamics, quantum physics a bit. Alot of math and equations. And some of this stuff literally makes my brain hurt thinking it through. :D

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Unobscured Vision    2,676

I've read that before, and that there were experiments being conducted that would either prove or disprove those theories. I believe that it runs into a Quantum Function called "Subjection"; since those instruments themselves were also virtual (since they currently exist within that time/space continuum, they are subject to its' quantum and physical laws) they would be unable to discriminate whether the universe(s) they were sampling were real or virtual.

 

So, in short, the jury is still out, and we might never know for sure.

 

(It's part of a larger "whole" of Quantum Mechanical Wave Function, folks. :yes: Thank Soule's "Looking for the Tallyman", Pardo's "Archetypical Phsychology" and Johnson's "Quantum Theatre: Science and Contemporary Performance"; all of which have been endorsed by David Ellerman.)

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