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Draggendrop    5,747

Millisecond Pulsars Likely Account for Signal in Galactic Center

 

art-accreting-x-ray-millisecond-pulsar-l

Millisecond pulsars, or rapidly rotating neutron stars, were often formed billions of years ago. They are among the most extreme objects in the galaxy. A population of hundreds or thousands of these millisecond pulsars must be lurking in the galactic center, hidden from detection due to present day instrument sensitivity.

 

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The puzzling excess of gamma rays from the center of the Milky Way probably originates from rapidly rotating neutron stars, or millisecond pulsars, and not from dark matter annihilation, as previously claimed.

 

This is the conclusion of new data analyzes by two independent research teams from the University of Amsterdam (UvA) and Princeton University/Massachusetts Institute of Technology. The researchers' findings are published in Physical Review Letters.

 

In 2009 observations with the Fermi Large Area Telescope revealed an excess of high-energy photons, or gamma rays, around 2 GeV (giga-electron volts) at the center of our galaxy. It was long speculated that this gamma ray excess could be a signal of dark matter annihilation. If true, it would constitute a breakthrough in fundamental physics and a major step forward in our understanding of the matter constituents of the universe.

 

However, many other hypotheses have emerged in recent years, suggesting the gamma ray excess in the center of our galaxy might have a more ordinary, astrophysical cause. Possible origins for the observed gamma ray excess range from the activity of the supermassive black hole in the center of our Milky Way and star formation in the central molecular zone to the combined emission of a new dim source population in the galactic bulge.

 

Millisecond Pulsars
New statistical analyzes of the Fermi data by Dr. Christoph Weniger, assistant professor at the UvA, and a research group from Princeton/MIT now strongly suggest that the excess emission does indeed originate from unresolved point sources. The best candidates are millisecond pulsars, the researchers conclude.

 

Millisecond pulsars, or rapidly rotating neutron stars, were often formed billions of years ago. They are among the most extreme objects in the galaxy. A population of hundreds or thousands of these millisecond pulsars must be lurking in the galactic center, hidden from detection due to present day instrument sensitivity. Future radio surveys with existing and upcoming telescopes (e.g., Green Bank Telescope, Square Kilometre Array) will be able to further test this hypothesis in the coming years.

 

Win-Win Situation
In their analyzes, the UvA and Princeton/MIT researchers each used a different statistical technique, 'non-Poissonian noise' and 'wavelet transformation,' to analyze the Fermi data. What they found was that the distribution of photons was clumpy rather than smooth, indicating that the gamma rays were unlikely to be caused by dark matter particle collisions.

 

According to Weniger, lead author of one of the papers, this is a win-win situation: "Either we find hundreds or thousands of millisecond pulsars in the upcoming decade, shedding light on the history of the Milky Way, or we find nothing. In the latter case, a dark matter explanation for the gamma ray excess will become much more obvious."

 

Mariangela Lisanti, assistant professor at Princeton University and one of the authors of the second paper, adds: "The results of our analysis probably mean that what we are seeing is evidence for a new population of astrophysical sources in the center of the galaxy. That in itself is something new and surprising."

http://www.spacedaily.com/reports/Millisecond_Pulsars_Likely_Account_for_Signal_in_Galactic_Center_999.html

 

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.051103

 

:)

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Draggendrop    5,747

Entertainment for the weekend...

 

I thought these two video's were a bit of fun and twists general knowledge in a new light....just entertainment, what do you think...?

 

How Hot Can It Get?

video is 10:02 min.

 

 

 

 

 

What's The Brightest Thing In the Universe?

video is 11:55 min.

 

 

 

:)

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LOC    989

I love Vsauce (and Vsauce3,  2 not so much anymore). He's another Neil Degrasse Tyson if you ask me, just uh, shorter and not a degree holding head of a planeterium etc :D

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Draggendrop    5,747
1 hour ago, LOC said:

I love Vsauce (and Vsauce3,  2 not so much anymore). He's another Neil Degrasse Tyson if you ask me, just uh, shorter and not a degree holding head of a planeterium etc :D

Yes...knowledge is fun when it is made entertaining.....:D

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Draggendrop    5,747

'Cannibalism' between stars

 

simulation-of-gravitationally-unstable-c

This is a Simulation of a gravitationally unstable circumstellar disk by means of hydrodynamic calculations. Protoplanetary 'embryo' form in the disc thanks to gravitational fragmentation. The three small pictures show the successive 'disappearance' of the lump by the star. Credit: Eduard Vorobyov, Universitat Wien

 

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Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disk forming around the star owing to conservation of angular momentum. The manner in which the material is transported through the disk onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.

 

It turned out that stars may not accumulate their final mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.

 

One possible mechanism that can explain these brightening events was put forward 10 years ago by Eduard Vorobyov, now working at the Astrophysical Department of the Vienna University, in collaboration with Shantanu Basu from the University of Western Ontario, Canada.

 

According to their theory, stellar brightening can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star.

 

Like the process of throwing logs into a fireplace, these episodes of clump consumption release excess energy which causes the young star to brighten by a factor of hundreds to thousands. During each episode, the star is consuming the equivalent of one Earth mass every ten days. After this, it may take another several thousand years before another event occurs.

 

Eduard Vorobyov describes the process of clump formation in circumstellar disks followed by their migration onto the star as "cannibalism on astronomical scales". These clumps could have matured into giant planets such as Jupiter, but instead they were swallowed by the parental star. This invokes an interesting analogy with the Greek mythology, wherein Cronus, the leader of the first generation of Titans, ate up his newborn children (though failing to gobble up Zeus, who finally brought death upon his father).

 

With the advent of advanced observational instruments, such as SUBARU 8.2 meter optical-infrared telescope installed in Mauna Kea (Hawaii), it has become possible for the first time to test the model predictions.

 

Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model - large-scale arms and arcs surrounding four young stars undergoing luminous outbursts, including the prototype FU Orionis star itself.

 

The results of this study were accepted for publication in Science Advances - a peer-review, open-access journal belonging to the Science publishing group.

 

"This is a major step towards our understanding of how stars and planets form and evolve", says Vorobyov, "If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own Sun might have experienced several such episodes, implying that the giant planets of the Solar system may in fact be lucky survivors of the Sun's tempestuous past".

http://www.spacedaily.com/reports/Cannibalism_between_stars_999.html

 

:D

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Draggendrop    5,747

Hundreds of Hidden Galaxies Glimpsed Behind Milky Way (Video)

 

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A new telescope view has revealed hundreds of galaxies that were previously obscured by the Milky Way's bulk.

 

Scientists used an Australian radio telescope famous for assisting with the moon landings to peer through the gas and dust of the Milky Way, and uncovered 883 galaxies hidden behind it — one-third of which were never observed before. You can see how the hidden galaxies were found in this video.

 

This new view of the region could help explain something called the Great Attractor, which is a mysterious spot in the universe whose strong gravity pulls on the Milky Way and thousands of other galaxies with "the force equivalent to a million billion suns," researchers said in a statement. Scientists have known about the phenomenon since the 1970s.

 

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Artist's impression of the galaxies behind the Milky Way in the "Zone of Avoidance."
Credit: ICRAR

 

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"The Milky Way is very beautiful, of course, and it's very interesting to study our own galaxy, but it completely blocks out the view of the more distant galaxies behind it," lead author Lister Staveley-Smith, director of science with the International Centre for Radio Astronomy Research (ICRAR) said in the statement.

 

The new observations, made using the Commonwealth Scientific and Industrial Research Organization (CSIRO) Parkes Observatory, in Australia, found three new galaxy concentrations (NW1, NW2 and NW3) and two new clusters (CW1 and CW2). The researchers put a new, 21-centimeter (8.3 inches) multibeam receiver on the observatory that allowed it to map the sky 13 times faster than it had previously, officials said in the statement.

 

Thus, they were able to pin down a region beyond the Milky Way that astronomers had wondered about for decades. With further work, the team hopes the discoveries will help explain observed anomalies within the universal expansion of the cosmos, like the Great Attractor, researchers said.

"We don't actually understand what's causing this gravitational acceleration on the Milky Way or where it's coming from," Staveley-Smith said.

 

"We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than 2 million km/h [1.2 million mph]," he added.

 

The research was detailed in The Astronomical Journal Feb. 9.

http://www.space.com/31872-hidden-galaxies-behind-milky-way-revealed.html

 

Radio Telescope Reveals Hundreds Of Hidden Galaxies Behind Milky Way's Haze | Video

video is 1:18 min.

 

 

 

 

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Galactic Space Oddity Discovered

 

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An international team of researchers led by Aaron Romanowsky of San José State University has used the Subaru Telescope to identify a faint dwarf galaxy disrupting around a nearby giant spiral galaxy. The observations provide a valuable glimpse of a process that is fleeting but important in shaping galaxies.

 

"The outer regions of giant galaxies like our own Milky Way appear to be a jumble of debris from hundreds of smaller galaxies that fell in over time and splashed into smithereens," said Romanowsky. "These dwarfs are considered building blocks of the giants, but the evidence for giants absorbing dwarfs has been largely circumstantial. Now we have caught a pair of galaxies in the act of a deadly embrace." (Figure 1)

 

http://subarutelescope.org/Pressrelease/2016/02/08/fig1e.jpg

(may have to open in another tab, large image and the editor dislikes me today)

 

 

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The two objects in the study are NGC 253, also called the Silver Dollar galaxy, and the newly discovered dwarf NGC 253-dw2. They are located in the Southern constellation of Sculptor at a distance of 11 million light years from Earth, and are separated from each other by about 160 thousand light years. The dwarf has an elongated appearance that is the hallmark of being stretched apart by the gravity of a larger galaxy.

 

"The dwarf has been trapped by its giant host and will not survive intact for much longer," said team member Nicolas Martin, of the Strasbourg Observatory. "The next time it plunges closer to its host, it could be shredded into oblivion. However, the host may suffer some damage too, if the dwarf is heavy enough."

 

The interplay between the two galaxies may resolve an outstanding mystery about NGC 253, as the giant spiral shows signs of being disturbed by a dwarf. The disturber was previously unseen and presumed to have perished, but now the likely culprit has been found. "This looks like a case of galactic stealth attack," said Gustavo Morales of Heidelberg University. "The dwarf galaxy has dived in from the depths of space and barraged the giant, while remaining undetected by virtue of its extreme faintness."

 

The discovery of NGC 253-dw2 has an unusual pedigree. It began with a digital image of the giant galaxy taken by astrophotographer Michael Sidonio using a 30 centimeter (12 inch) diameter amateur telescope in Australia. Other members of the international team noticed a faint smudge in the image and followed it up with a larger, 80 centimeter (30 inch) amateur telescope in Chile, led by Johannes Schedler. The identity of the object was still not clear, and it was observed with the 8 meter (27 foot) Subaru Telescope on the summit of Mauna Kea in Hawaii, in December 2014. "In the first image, we weren't sure if there was really a faint galaxy or if it was some kind of stray reflection," said David Martínez-Delgado, also from Heidelberg University. "With the high-quality imaging of the Suprime-Cam instrument on the Subaru Telescope, we can now see that the smudge is composed of individual stars and is a bona fide dwarf galaxy. This discovery is a wonderful example of fruitful collaboration between amateur and professional astronomers." (Figure 2)

 

fig2e.jpg

Figure 2: Close-up view of the dwarf galaxy NGC 253-dw2. The closely packed red dots show that it is composed of individual stars. Click here for the original tiff file. (Image credit: Copyright © 2015 R. Jay GaBany (Cosmotography.com), Zachary Jennings (University of California, Santa Cruz), and National Astronomical Observatory of Japan (NAOJ)).

 

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The findings are in research paper published in the Monthly Notices of the Royal Astronomical Society Letters by Oxford University Press, as "Satellite accretion in action: a tidally disrupting dwarf spheroidal around the nearby spiral galaxy NGC 253" by Romanowsky et al., first online on January 23, 2016 (http://mnrasl.oxfordjournals.org/lookup/doi/10.1093/mnrasl/slv207).

http://subarutelescope.org/Pressrelease/2016/02/08/index.html

 

:)

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Draggendrop    5,747

Newly Formed Star Lights Up Surrounding Cosmic Clouds

 

eso1605a.jpg

IC 2631     ESO

 

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The glowing region in this new image from the MPG/ESO 2.2-metre telescope is a reflection nebula known as IC 2631.

 

These objects are clouds of cosmic dust that reflect light from a nearby star into space, creating a stunning light show like the one captured here. IC 2631 is the brightest nebula in the Chamaeleon Complex, a large region of gas and dust clouds that harbours numerous newborn and still-forming stars. The complex lies about 500 light-years away in the southern constellation of Chamaeleon.

 

IC 2631 is illuminated by the star HD 97300, one of the youngest -- as well as most massive and brightest -- stars inits neighbourhood. This region is full of star-making material, which is made evident by the presence of dark nebulae noticeable above and below IC 2631 in this picture. Dark nebulae are so dense with gas and dust that they prevent the passage of background starlight.

 

Despite its dominating presence, the heft of HD 97300 should be kept in perspective. It is a T Tauri star, the youngest visible stage for relatively small stars. As these stars mature and reach adulthood they will lose mass and shrink. But during the T Tauri phase these stars have not yet contracted to the more modest size that they will maintain for billions of years as main sequence stars .

 

These fledging stars already have surface temperatures similar to their main sequence phase and accordingly, because T Tauri-phase objects are essentially jumbo versions of their later selves, they look brighter in their oversized youth than in maturity. They have not yet started to fuse hydrogen into helium in their cores, like normal main sequence stars, but are just starting to flex their thermal muscles by generating heat from contraction.

 

Reflection nebula, like the one spawned by HD 97300, merely scatter starlight back out into space. Starlight that is more energetic, such as the ultraviolet radiation pouring forth from very hot new stars, can ionise nearby gas, making it emit light of its own. These emission nebulae indicate the presence of hotter and more powerful stars, which in their maturity can be observed across thousands of light-years. HD 97300 is not so powerful, and its moment in the spotlight is destined not to last.

http://spaceref.com/astronomy/newly-formed-star-lights-up-surrounding-cosmic-clouds.html

 

http://www.eso.org/public/news/eso1605/

 

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LARGEST ROCKY WORLD FOUND

 

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An illustration of a large, rocky planet similar to the recently discovered BD+20594b. Image: JPL-Caltech/NASA

 

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We thought we understood how big rocky planets can get. But most of our understanding of planetary formation and solar system development has come from direct observation of our own Solar System. We simply couldn’t see any others, and we had no way of knowing how typical—or how strange—our own Solar System might be.

 

But thanks to the Kepler Spacecraft, and it’s ability to observe and collect data from other, distant, solar systems, we’ve found a rocky planet that’s bigger than we thought one could be. The planet, called BD+20594b, is half the diameter of Neptune, and composed entirely of rock.

 

The planet, whose existence was reported on January 28 at arXiv.org by astrophysicist Nestor Espinoza and his colleagues at the Pontifical Catholic University of Chile in Santiago, is over 500 light years away, in the constellation Aries.

 

BD+20594b is about 16 times as massive as Earth and half the diameter of Neptune. Its density is about 8 grams per cubic centimeter. It was first discovered in 2015 as it passed in between Kepler and its host star. Like a lot of discoveries, a little luck was involved. BD+20594b’s host star is exceptionally bright, which allowed more detailed observations than most exoplanets.

 

The discovery of BD+20594b is important for a couple of reasons: First, it shows us that there’s more going on in planetary formation than we thought. There’s more variety in planetary composition than we could’ve known from looking at our own Solar System. Second, comparing BD+20594b to other similar planets, like Kepler 10c—a previous candidate for largest rocky planet—gives astrophysicists an excellent laboratory for testing out our planet formation theories.

 

It also highlights the continuing importance of the Kepler mission, which started off just confirming the existence of exoplanets, and showing us how common they are. But with discoveries like this, Kepler is flexing its muscle, and starting to show us how our understanding of planetary formation is not as complete as we may have thought.

http://www.universetoday.com/127325/largest-rocky-world-found/

 

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I just thought this was neat.....

 

Running from Beauty: A Darker Side of Orion | Space Wallpaper

 

runningman-1977-1600.jpg?interpolation=l

 

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This region of Orion is oft overlooked by astronomers who are attracted to the contrasting brilliant and bright colors of the Orion Nebula's stellar nursery. Yet in this image of NGC 1977, NGC 1975 and NGC 1973 — which are reminiscent of a running man — the gentle blues, grays and purples of these reflection nebulae demand respect for their own, unique beauty.

Lots of sizes at the link...

http://www.space.com/31889-running-from-beauty-a-darker-side-of-orion.html

 

:D

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Jim K    12,825

Physicists make an announcement about Gravitational Waves.

 

LiveStream

 

 

 

 

 

http://www.sciencemag.org/news/2016/02/woohoo-email-stokes-rumor-gravitational-waves-have-been-spotted
 

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It's just a rumor, but if specificity is any measure of credibility, it might just be right. For weeks, gossip has spread around the Internet that researchers with the Laser Interferometer Gravitational-Wave Observatory (LIGO) have spotted gravitational waves—ripples in space itself set off by violent astrophysical events. In particular, rumor has it that LIGO physicists have seen two black holes spiraling into each other and merging. But now, an email message that ended up on Twitter adds some specific numbers to those rumors. The author says he got the details from people who have seen the manuscript of the LIGO paper that will describe the discovery.

 

 

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Draggendrop    5,747

Gravitational wave has been detected, a high energy, short duration pulse, for which this system was designed. Great news...here is the first part of the livestream....

 

Scientists Announce Discovery Of Gravitational Waves

video is 7:04 min.

 

 

 

 

As well, another livestream which may have Dr. Hawking in a teleconference, since he has a research chair there and was instrumental in it's formation.

 

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Then, at 1 p.m. EST (1800 GMT), the Perimeter Institute for Theoretical Physics in Ontario, Canada, will host its own webcast about the gravitational-wave announcement and its implications. Space.com will carry that event live as well in the window below, thanks to the Perimeter Institute:

http://www.space.com/17933-nasa-television-webcasts-live-space-tv.html

 

articles on the discovery...

 

http://www.livescience.com/53684-gravitational-waves-found.html

 

http://www.scientificamerican.com/article/gravitational-waves-discovered-from-colliding-black-holes1/

 

http://www.eurekalert.org/pub_releases/2016-02/nsf-gwd021116.php

 

http://www.popsci.com/its-official-ligo-found-gravitational-waves

 

:D

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LOC    989

Incredible that we could detect this, and finally after over 100 years, prove Einstein correct yet again. And the "chirp" that you can hear from the merging is amazing, just amazing. I never thought when I was in college they would have done this in the next 20 or 30 years.

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Draggendrop    5,747
5 hours ago, LOC said:

Incredible that we could detect this, and finally after over 100 years, prove Einstein correct yet again. And the "chirp" that you can hear from the merging is amazing, just amazing. I never thought when I was in college they would have done this in the next 20 or 30 years.

I'll bet you would have a blast working there with them....grin ear to ear....:D

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Draggendrop    5,747

Supermassive Black Hole in Elliptical Galaxy NGC 4889

 

heic1602a.jpg

The placid appearance of NGC 4889 can fool the unsuspecting observer. But the elliptical galaxy, pictured in this new image from the NASA/ESA Hubble Space Telescope, harbours a dark secret. At its heart lurks one of the most massive black holes ever discovered.   

(Low center bright one)

 

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The placid appearance of NGC 4889 can fool the unsuspecting observer.

 

But the elliptical galaxy, pictured in this new image from the NASA/ESA Hubble Space Telescope, harbours a dark secret. At its heart lurks one of the most massive black holes ever discovered.

 

Located about 300 million light-years away in the Coma Cluster, the giant elliptical galaxy NGC 4889, the brightest and largest galaxy in this image, is home to a record-breaking supermassive black hole. Twenty-one billion times the mass of the Sun, this black hole has an event horizon the surface at which even light cannot escape its gravitational grasp with a diameter of approximately 130 billion kilometres. This is about 15 times the diameter of Neptune's orbit from the Sun. By comparison, the supermassive black hole at the centre of our galaxy, the Milky Way, is believed to have a mass about four million times that of the Sun and an event horizon just one fifth the orbit of Mercury.

 

But the time when NGC 4889's black hole was swallowing stars and devouring dust is past. Astronomers believe that the gigantic black hole has stopped feeding, and is currently resting after feasting on NGC 4889's cosmic cuisine. The environment within the galaxy is now so peaceful that stars are forming from its remaining gas and orbiting undisturbed around the black hole.

 

When it was active, NGC 4889's supermassive black hole was fuelled by the process of hot accretion. When galactic material such as gas, dust and other debris slowly fell inwards towards the black hole, it accumulated and formed an accretion disc. Orbiting the black hole, this spinning disc of material was accelerated by the black hole's immense gravitational pull and heated to millions of degrees. This heated material also expelled gigantic and very energetic jets. During its active period, astronomers would have classified NGC 4889 as a quasar and the disc around the supermassive black hole would have emitted up to a thousand times the energy output of the Milky Way.

 

The accretion disc sustained the supermassive black hole's appetite until the nearby supply of galactic material was exhausted. Now, napping quietly as it waits for its next celestial snack, the supermassive black hole is dormant. However its existence allows astronomers to further their knowledge of how and where quasars, these still mysterious and elusive objects, formed in the early days of the Universe.

 

Although it is impossible to directly observe a black hole as light cannot escape its gravitational pull its mass can be indirectly determined. Using instruments on the Keck II Observatory and Gemini North Telescope, astronomers measured the velocity of the stars moving around NGC 4889's centre. These velocities which depend on the mass of the object they orbit revealed the immense mass of the supermassive black hole.

 

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

http://spaceref.com/astronomy/supermassive-black-hole-in-elliptical-galaxy-ngc-4889.html

 

http://www.spacetelescope.org/news/heic1602/

 

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Atacama Pathfinder Experiment in Chile Starts Its Second Decade

 

12m-apex-telescope-atacama-desert-lg.thu

Guests of the event visiting the 12 m APEX telescope, 5100 m above sea level in the Chilean Atacama desert.

 

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The Atacama Pathfinder Experiment (APEX) is a radio telescope of 12 meters diameter for observations at submillimeter wavelengths. It was built at a very specific site, the Chajnantor plateau in the Atacama desert in Northern Chile, at an altitude of more than 5,000 m above sea level, thus providing access to the otherwise blocked submillimeter range of the electromagnetic spectrum. The Chajnantor plateau also hosts the telescopes of the Atacama Large Millimeter/submillimeter Array (ALMA).

 

On January 25-26, the 10th anniversary of APEX was celebrated at the APEX base station in Sequitor, San Pedro de Atacama, at a better accessible altitude of only 2,500 m above sea level. A number of special guests were present at the occasion, including the German ambassador in Chile, Rolf Schulze, the President of the Max-Planck-Gesellschaft, Prof. Martin Stratmann, and the Director General of the European Southern Observatory (ESO), Prof. Tim de Zeeuw.

 

For the partners in the APEX collaboration, principal investigator Prof. Karl Menten and APEX project manager Dr. Rolf Gusten from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn, Germany, and Prof. John Conway, Director of the Swedish Onsala Space Observatory (OSO) were attending the event. Fig. 1 shows the group of visitors at the high-altitude APEX site.

more at the link...

http://www.spacedaily.com/reports/Atacama_Pathfinder_Experiment_in_Chile_Starts_Its_Second_Decade_999.html

 

:)

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Unobscured Vision    2,651

And the really scary thing about 4889?

 

That "glow" isn't a lens flare. That's how big the galaxy really is.

 

There are a few of them we've observed that are big like that. Several million to several tens of millions of light-years across. They eat whole galaxies. There's so little star formation going on that all that's left are the small, relatively cool K-Subdwarfs and M-Dwarf Stars (that can last for a trillion years before exhausting their supplies of Hydrogen) on down thru the HR-Diagram, to the Brown Dwarfs that are sorta fusing deuterium but are still 80 times the mass of Jupiter (and likely are small analogues of Solar Systems themselves). Once in a while, that monster chomps another galaxy, and a burst of star formation occurs because there's new gases introduced, but it never lasts ...

 

Can you imagine how much life there is in a galaxy like 4889? It's obviously a very stable place, Astrophysically. Probably quite dull, too. Not much to look at, aside from the myriad of worlds there.

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Draggendrop    5,747

NASA Time-lapse Shows Webb Telescope Mirror Assembly

 

jwst-18-mirrors-fully-installed-lg.jpg

This time-lapse shows the assembly of the primary mirror of NASA's James Webb Space Telescope. Assembly was completed on February 3, 2016. Image courtesy NASA Goddard Space Flight Center.

 

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NASA's latest time-lapse video shows the James Webb Space Telescope's primary mirror's full assembly from start to finish. The video, which covers almost three months of work has been sped up to run just over a minute to cover this meticulous labor-intensive procedure. Using a robotic arm reminiscent of a claw machine, the team meticulously installed all of Webb's primary mirror segments onto the telescope structure.

 

"Installing the primary mirror segments onto the telescope structure was an amazing team effort amongst incredibly talented engineers and technicians and one highly reliable robot," said Lee Feinberg, optical telescope element manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Building the primary mirror is a key milestone in the development of any telescope and this is especially the case for Webb."

Each of the hexagonal-shaped mirror segments measures just over 4.2 feet (1.3 meters) across - about the size of a coffee table - and weighs approximately 88 pounds (40 kilograms). Once in space and fully deployed, the 18 primary mirror segments will work together as one large 21.3-foot diameter (6.5-meter) mirror.

 

The James Webb Space Telescope team completed this significant milestone, but continues to work on other key steps to build and test this tennis-court sized space telescope.

 

"Between now and early 2017 will be the most significant year to date in the integration and test of Webb," said Bill Ochs, James Webb Space Telescope project manager. "Each of the four major elements, the telescope, science instrument package, spacecraft bus, and sunshield, will be delivered and will be integrated into the two major pieces which make up the observatory."

 

Photographer Chris Gunn and Producer Michael McClare, both from NASA Goddard collaborated to produce the video. They captured 141,639 images for the time-lapse at a rate of one image taken every 30 seconds between November 11, 2015 and February 1, 2016 - 83 days total.

 

"Months before the mirror installation began, I looked for the perfect time-lapse camera placement, one that would give viewers an unprecedented look at the mirror integration of the space telescope," Gunn said. "When I decided that the best place to mount the camera would be on the 'over deployment fixture' directly above telescope structure I expected the mirror integration team to reject the proposal. After they verified the safety of our proposed camera set-up they were just as enthusiastic about the idea as I was."

 

Gunn and McClare have been following the engineers and technicians documenting their work.

 

"Chris and I knew this angle would be spectacular. The camera location presented a myriad of challenges due to the sensitive work environment," said McClare. "The camera is about 50-feet above the ground securely affixed to a structure near the spacecraft, it could not be directly accessed after it was mounted. Our system had to work continuously for almost four months capturing the complete mirror installation."

 

The mirrors were built by Ball Aerospace and Technologies Corp., in Boulder, Colorado. Ball is the principal subcontractor to Northrop Grumman for the optical technology and optical system design. The installation of the mirrors onto the telescope structure is performed by Harris Corporation, a subcontractor to Northrop Grumman. Harris Corporation leads integration and testing for the telescope.

 

The James Webb Space Telescope is the scientific successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb will study many phases in the history of our universe, including the formation of solar systems capable of supporting life on planets similar to Earth, as well as the evolution of our own solar system. It's targeted to launch from French Guiana aboard an Ariane 5 rocket in 2018. Webb is an international project led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.

http://www.spacedaily.com/reports/NASA_Time_lapse_Shows_Webb_Telescope_Mirror_Assembly_999.html

 

Time-lapse: The Assembly of the James Webb Space Telescope Primary Mirror

video is 1:24 min.

 

 

 

 

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

 

Rare Supernova Impostor in a Nearby Galaxy

 

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SN 2010da                     UNIVERSITY OF WASHINGTON

 

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Breanna Binder, a University of Washington postdoctoral researcher in the Department of Astronomy and lecturer in the School of STEM at UW Bothell, spends her days pondering X-rays.

 

As she and her colleagues report in a new paper published Feb. 12, 2016 in the Monthly Notices of the Royal Astronomical Society, they recently solved a mystery involving X-rays -- a case of X-rays present when they shouldn't have been. This mystery's unusual main character -- a star that is pretending to be a supernova -- illustrates the importance of being in the right place at the right time.

 

Such was the case in May 2010 when an amateur South African astronomer pointed his telescope toward NGC300, a nearby galaxy. He discovered what appeared to be a supernova -- a massive star ending its life in a blaze of glory.

 

"Most supernovae are visible for a short time and then -- over a matter of weeks -- fade from view," said Binder.

 

After a star explodes as a supernova, it usually leaves behind either a black hole or what's called a neutron star -- the collapsed, high-density core of the former star. Neither should be visible to Earth after a few weeks. But this supernova -- SN 2010da -- still was.

 

"SN 2010da is what we call a 'supernova impostor' -- something initially thought to be a supernova based on a bright emission of light, but later to be shown as a massive star that for some reason is showing this enormous flare of activity," said Binder.

 

Many supernova impostors appear to be massive stars in a binary system -- two stars in orbit of one another. Stellar astrophysicists think that the impostor's occasional flare-ups might be due to perturbations from its neighbor.

 

For SN 2010da, the story appeared to be over until September 2010 -- four months after it was confirmed as an impostor -- when Binder pointed NASA's Chandra X-ray Observatory toward NGC300 and found something unexpected.

 

"There was just this massive amount of X-rays coming from SN 2010da, which you should not see coming from a supernova impostor," she said.

Binder considered a variety of explanations. For example, material from the star's corona could be hitting a nearby dust cloud. But that would not produce the level of X-rays she had observed. Instead, the intensity of the X-rays coming from SN 2010da were consistent with a neutron star -- the dense, collapsed core remnant of a supernovae.

 

"A neutron star at this location would be surprising," said Binder, "since we already knew that this star was a supernova impostor -- not an actual supernova."

 

In 2014, Binder and her colleagues looked at this system again with Chandra and, for the first time, the Hubble Space Telescope. They found the impostor star and those puzzling X-ray emissions. Based on these new data, they concluded that, like many other supernovae impostors, SN 2010da likely has a companion. But, unlike any other supernovae impostor binary reported to date, SN 2010da is probably paired with a neutron star.

"If this star's companion truly is a neutron star, that would mean that the neutron star was once a giant, massive star that underwent its own supernova explosion in the past," said Binder. "The fact that this supernova event didn't expel the other star, which is 20 to 25 times the mass of our sun, makes this an incredibly rare type of binary system."

 

To understand how this unusual binary system could form, Binder and her colleagues considered the age of the stars in this region of space. Looking at stellar size and luminosity, they discovered that most nearby stars were created in two bursts -- one 30 million years ago and the other less than 5 million years ago. But neither SN 2010da nor its presumed neutron star companion could've been created in the older burst of starbirth.

 

"Most stars that are as massive as these usually live 10 to 20 million years, not 30 million," said Binder. "The most massive, hottest stars can form, grow, swell, explode and leave a neutron star emitting X-rays in about 5 million years."

 

Surveys of the galaxy as recently as 2007 and 2008 detected no X-ray emissions from the location of SN 2010da. Instead, Binder believes that the X-rays they first found in 2010 represent the neutron star "turning on" for the first time after its formation. The X-rays are likely produced when material from the impostor star is transferred to the neutron star companion.

 

"That would mean that this is a really rare system at an early stage of formation," said Binder, "and we could learn a lot about how massive stars form and die by continuing to study this unique pairing."

 

One mystery solved, Binder would like to keep looking at SN 2010da, seeing what else she can learn about its formation and evolution. Its home galaxy, which has yielded unique pairings previously, is sure to keep her busy. She is also planning a follow-up study of other recent supernova impostors with the help of an undergraduate research assistant at UW Bothell.

 

Co-authors on the paper included UW astronomy professor Ben Williams, Albert Kong at the National Tsing Hua University, Terry Gaetz and Paul Plucinsky at the Harvard-Smithsonian Center for Astrophysics, Evan Skillman at the University of Minnesota and Andrew Dolphin at Raytheon. Their work was funded by NASA.

http://spaceref.com/astronomy/rare-supernova-impostor-in-a-nearby-galaxy.html

 

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

 

Neil deGrasse Tyson Explains Einstein's Gravitational Waves Theory

video is 6 :00 min.

 

 

 

 

:D

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Draggendrop    5,747

IC 1805, The Heart Nebula

 

Heart_Addis_2504.jpg

Bright from the Heart Nebula 
Image Copyright: Simon Addis

 

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Explanation: What's that inside the Heart Nebula? First, the large emission nebula dubbed IC 1805 looks, in whole, like a human heart. The nebula glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center. In the center of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their energetic light and winds. The open cluster of stars contains a few bright stars nearly 50 times the mass of our Sun, many dim stars only a fraction of the mass of our Sun, and an absent microquasar that was expelled millions of years ago. The Heart Nebula is located about 7,500 light years away toward the constellation of Cassiopeia. At the top right is the companion Fishhead Nebula.

http://apod.nasa.gov/apod/ap151027.html

 

 

Here is another view, turned 90 degree's clockwise...

 

ic1805rgbBig.jpg

 

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Planet Formation around Binary Star:

 

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ALMA reveals planet-forming potential of protoplanetary disk

Summary: Using ALMA, astronomers have taken a new, detailed look at the very early stages of planet formation around a binary star. Embedded in the outer reaches of a double star's protoplanetary disk, the researchers discovered a striking crescent-shape region of dust that is conspicuously devoid of gas. This result, presented at the AAAS meeting in Washington, D.C., provides fresh insights into the planet-forming potential of a binary system.

 

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An illustration shows the HD 142527 binary star system from data captured by the Atacama Large Millimeter/submillimeter Array. The red body orbiting the center represents the low-mass companion star. Click image for a larger version. Illustration by B. Saxton/NRAO/AUI/NSF

 

 

 

cc_planetforming_free.jpg

A composite image of the HD 142527 binary star system from data captured by the Atacama Large Millimeter/submillimeter Array shows dust in red and carbon monoxide gases in blue and green. The carbon monoxide isotopologues are used to probe the distribution of gases in protoplanetary disks, according to Rice University astrophysicist Andrea Isella. A representation of Earth’s solar system at bottom right is to scale. Click image for a larger version. Courtesy of: Andrea Isella

 

 

Quote

Astronomers struggle to understand how planets form in binary star systems. Early models suggested that the gravitational tug-of-war between two stellar bodies would send young planets into eccentric orbits, possibly ejecting them completely from their home system or sending them crashing into their stars. Observational evidence, however, reveals that planets do indeed form and maintain surprisingly stable orbits around double stars. 

To better understand how such systems form and evolve, astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) took a new, detailed look at the planet-forming disk around HD 142527, a binary star about 450 light-years from Earth in a cluster of young stars known as the Scorpius-Centaurus Association. 

 

The HD 142527 system includes a main star a little more than twice the mass of our Sun and a smaller companion star only about a third the mass of our Sun. They are separated by approximately one billion miles: a little more than the distance from the Sun to Saturn. Previous ALMA studies of this system revealed surprising details about the structure of the system's inner and outer disks. 

 

"This binary system has long been known to harbor a planet-forming corona of dust and gas," said Andrea Isella, an astronomer at Rice University in Houston, Texas. "The new ALMA images reveal previously unseen details about the physical processes that regulate the formation of planets around this and perhaps many other binary systems."

 

Planets form out of the expansive disks of dust and gas that surround young stars. Small dust grains and pockets of gas come together under gravity, forming larger and larger agglomerations and eventually asteroids and planets. The fine points of this process are not well understood, however. By studying a wide range of protoplanetary disks with ALMA, astronomers hope to better understand the conditions that set the stage for planet formation across the Universe. 

 

ALMA's new, high-resolution images of HD 142527 show a broad elliptical ring around the double star. The disk begins incredibly far from the central star -- about 50 times the Sun-Earth distance. Most of it consists of gases, including two forms of carbon monoxide (13CO and C180), but there is a noticeable dearth of these gases within a huge arc of dust that extends nearly a third of the way around the star system. 

 

This crescent-shaped dust cloud may be the result of gravitational forces unique to binary stars and may also be the key to the formation of planets, Isella speculates. Its lack of free-floating gases is likely the result of them freezing out and forming a thin layer of ice on the dust grains. 

 

"The temperature is so low that the gas turns into ice and sticks to the grains," Isella said. "This process is thought to increase the capacity for dust grains to stick together, making it a strong catalyst for the formation of planetesimals, and, down the line, of planets." 

 

"We've been studying protoplanetary disks for at least 20 years," Isella said. "There are between a few hundred and a few thousand we can look at again with ALMA to find new and surprising details. That's the beauty of ALMA. Every time you get new data, it's like opening a present. You don't know what's inside."

 

HD 142527 will be the subject of an upcoming paper led by Rice postdoctoral fellow Yann Boehler, who is working in Isella’s group.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

https://public.nrao.edu/news/pressreleases/binary-star-disk

 

http://spaceref.com/extrasolar-planets/planet-formation-around-a-binary-star.html

 

https://www.sciencenews.org/article/planets-may-emerge-stellar-duo-gathering-icy-dust?tgt=nr

 

http://www.eurekalert.org/pub_releases/2016-02/nrao-pfa020516.php

 

http://news.rice.edu/2016/02/13/proto-planet-has-two-masters-2/

 

:D

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Unobscured Vision    2,651

The Heart/Fishhead Nebula Complex has always been a favorite of mine, thanks DD. That's a great, clear image. It ranks up there with the Orion and Horsehead Nebulas for me (which, of course, hosts the "Pillars of Creation"). :yes: 

 

And those ALMA shots! MY GOD. STUNNING. No words beyond that. I had a smile on my face looking at those. :) 

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Unknown Wave-Like Phenomena Observed Surrounding Young Star 

 

6a00d8341bf7f753ef01b8d1a00057970c-800wi

 

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This past October, astronomers using NASA's Hubble Space Telescope and the European Southern Observatory's (ESO) Very Large Telescope in Chile iscovered never-before-seen features within the dusty disk surrounding the young, nearby star AU Microscopii (AU Mic).The fast-moving, wave-like structures are unlike anything ever observed, or even predicted in a circumstellar disk, said researchers of a new analysis. This new, unexplained phenomenon may provide valuable clues about how planets form inside these star-surrounding disks.

 

AU Mic (artists impression above) is located 32 light-years away in the southern constellation Microscopium. It is an optimal star to observe because its circumstellar disk is tilted edge-on to our view from Earth. This allow for certain details in the disk to be better seen. Astronomers have been searching AU Mic's disk for any signs of clumpy or warped features that might offer evidence for planet formation. They discovered a very unusual feature near the star by using ESO's SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) instrument, mounted on the Very Large Telescope.


"The images from SPHERE show a set of unexplained features in the disk, which have an arc-like, or wave-like structure unlike anything that has ever been observed before," said Anthony Boccaletti of the Paris Observatory, the paper's lead author.

 

The images reveal a train of wave-like arches, resembling ripples in water. After spotting the features in the SPHERE data the team turned to earlier Hubble images of the disk, taken in 2010 and 2011. These features were not recognized in the initial Hubble observations. But once astronomers reprocessed the Hubble images they not only identified the features but realized that they had changed over time. The researchers report that these ripples are moving -- and they are moving very fast.

 

6a00d8341bf7f753ef01b8d1a00076970c-800wi

 

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"We ended up with enough information to track the movement of these strange features over a four-year period," explained team member Christian Thalmann of the Swiss Federal Institute of Technology in Zurich, Switzerland. "By doing this, we found that the arches are racing away from the star at speeds of up to 10 kilometers per second (22,000 miles per hour)! Co-investigator Carol Grady of Eureka Scientific in Oakland, California, added, "Because nothing like this has been observed or predicted in theory we can only hypothesize when it comes to what we are seeing and how it came about."

 

The ripples farther away from the star seem to be moving faster than those closer to it. At least three of the features are moving so fast that they are escaping from the gravitational attraction of the star. Such high speeds rule out the possibility that these features are caused by objects, like planets, gravitationally disturbing material in the disk. The team has also ruled out a series of phenomena as explanations, including the collision of two massive and rare asteroid-like objects releasing large quantities of dust and spiral waves triggered by instabilities in the system's gravity.

 

"One explanation for the strange structure links them to the star's flares. AU Mic is a star with high flaring activity -- it often lets off huge and sudden bursts of energy from on or near its surface," said co-author Glenn Schneider of Steward Observatory in Phoenix, Arizona. "One of these flares could perhaps have triggered something on one of the planets -- if there are planets -- like a violent stripping of material, which could now be propagating through the disk, propelled by the flare's force."

 

The team plans to continue to observe the AU Mic system to try to understand what is happening. But, for now, these curious features remain an unsolved mystery.

 

The results will be published Oct. 8 in the British science journal Nature.

 

The Daily Galaxy via NASA/Goddard Space Flight Center

 

Image credit: NASA, ESA, ESO, A. Boccaletti (Paris Observatory) and wikimedia.org

http://www.dailygalaxy.com/my_weblog/2016/02/unknown-wave-like-phenomena-observed-surrounding-young-star-todays-most-popular.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+TheDailyGalaxyNewsFromPlanetEarthBeyond+%28The+Daily+Galaxy+--Great+Discoveries+Channel%3A+Sci%2C+Space%2C+Tech.%29

 

:)

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First detection of gases in super-Earth atmosphere

 

109085_web.jpg

IMAGE: THIS IS AN ARTIST'S IMPRESSION OF 55 CANCRI E FROM FURTHER AWAY. 

CREDIT: NASA/ESA HUBBLE SPACE TELESCOPE

 

Quote

The first successful detection of gases in the atmosphere of a super-Earth reveals the presence of hydrogen and helium, but no water vapour, according to UCL researchers. The exotic exoplanet, 55 Cancri e, is over eight times the mass of Earth and has previously been dubbed the 'diamond planet' because models based on its mass and radius have led some astronomers to speculate that its interior is carbon-rich.

 

Using new processing techniques on data from the NASA/ESA Hubble Space Telescope, a UCL-led team of European researchers has been able to examine the atmosphere of 55 Cancri e in unprecedented detail. The results will be published in the Astrophysical Journal.

 

"This is a very exciting result because it's the first time that we have been able to find the spectral fingerprints that show the gases present in the atmosphere of a super-Earth," said Angelos Tsiaras, a PhD student at UCL who developed the analysis technique along with colleagues Dr Ingo Waldmann and Marco Rocchetto in UCL Physics & Astronomy.

 

"Our analysis of 55 Cancri e's atmosphere suggests that the planet has managed to cling on to a significant amount of hydrogen and helium from the nebula from which it formed."

 

Super-Earths are thought to be the most common planetary type in our galaxy and are so-called because they have a mass larger than Earth but are still much smaller than the gas giants in the Solar System. The Wide Field Camera 3 (WFC3) on Hubble has already been used to probe the atmosphere of two super-Earths, but no spectral features were found in these previous studies.

 

55 Cancri e has a year that lasts 18 hours and temperatures on the surface are thought to reach around 2000 degrees Celsius. The planet is located in a solar system around 55 Cancri, a star in the Cancer constellation that is around 40 light-years from Earth. Because 55 Cancri is such a bright star, the team were able to use new analysis techniques to extract information about its planetary companion.

 

Observations were made by scanning WFC3 very quickly across the star to create a number of spectra. By combining these observations and processing through computer analytic 'pipeline' software, the researchers were able to retrieve the spectral fingerprints of 55 Cancri e embedded in the starlight.

 

"This result gives a first insight into the atmosphere of a super-Earth. We now have clues as to what the planet is currently like, how it might have formed and evolved, and this has important implications for 55 Cancri e and other super-Earths," said Professor Giovanna Tinetti (UCL Physics & Astronomy).

 

Intriguingly, the data also hinted at a signature for hydrogen cyanide, a marker for carbon-rich atmospheres.

 

"Such an amount of hydrogen cyanide would indicate an atmosphere with a very high ratio of carbon to oxygen," said Dr Olivia Venot, KU Leuven, Belgium, who developed an atmospheric chemical model of 55 Cancri e that supported the analysis of the observations.

 

"If the presence of hydrogen cyanide and other molecules is confirmed in a few years' time by the next generation of infrared telescopes, it would support the theory that this planet is indeed carbon rich and a very exotic place," said Professor Jonathan Tennyson (UCL Physics & Astronomy). "Although, hydrogen cyanide or prussic acid is highly poisonous, so it is perhaps not a planet I would like to live on!"

http://www.eurekalert.org/pub_releases/2016-02/ucl-fdo021616.php

 

With new detection technology, we are going to see some amazing results in a few years.

 

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

 

B3 0727+409: Glow from the Big Bang Allows Discovery of Distant Black Hole Jet

 

b30727_525.jpg

 

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A jet from a very distant black hole, called B3 0727+409, has been found using the Chandra X-ray Observatory.

 

The light from this jet was emitted just 2.7 billion light years after the Big Bang when the Universe was only one fifth its current age.

 

Jets in the early Universe such as this one give astronomers a way to probe the growth of black holes at a very early epoch.

 

Typically, such distant jets are discovered in radio waves first, but not B3 0727+409 that was first found by Chandra.

 

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The inset shows more detail of the X-ray emission from the jet detected by Chandra. The length of the jet in 0727+409 is at least 300,000 light years. Many long jets emitted by supermassive black holes have been detected in the nearby Universe, but exactly how these jets give off X-rays has remained a matter of debate. In B3 0727+409, it appears that the CMB is being boosted to X-ray wavelengths.

 

Scientists think that as the electrons in the jet fly from the black hole at close to the speed of light, they move through the sea of CMB radiation and collide with microwave photons. This boosts the energy of the photons up into the X-ray band to be detected by Chandra. If this is the case, it implies that the electrons in the B3 0727+409 jet must keep moving at nearly the speed of light for hundreds of thousands of light years.

 

The significance of this discovery is heightened because astronomers essentially stumbled across this jet while observing a galaxy cluster in the field. Historically, such distant jets have been discovered in radio waves first, and then followed up with X-ray observations to look for high-energy emission. If bright X-ray jets can exist with very faint or undetected radio counterparts, it means that there could be many more of them out there because astronomers haven't been systematically looking for them.

more at the link...

http://chandra.harvard.edu/photo/2016/b30727/

 

:)

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Hubble's Diamond in the Dust

 

hubble_friday_02192016.jpg?itok=iqGYCRTq

 

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Surrounded by an envelope of dust, the subject of this NASA/ESA Hubble Space Telescope image is a young forming star known as HBC 1. The star is in an immature and adolescent phase of life, while most of a sun-like star’s life is spent in a stable stage comparable to human adulthood.

 

In this view, HBC 1 illuminates a wispy reflection nebula known as IRAS 00044+6521. Formed from clouds of interstellar dust, reflection nebulae do not emit any visible light of their own.  Instead, like fog encompassing a lamppost, they shine via the light reflected off the dust from the stars embedded within. Though nearby stars cannot ionize the nebula’s dust, as they can for gas within brighter emission nebulae, scattered starlight can make the dust visible in a reflection nebula.

 

Text credit: European Space Agency
Image credit: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt

http://www.nasa.gov/image-feature/goddard/2016/hubbles-diamond-in-the-dust

 

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Astronomer from Moscow detected a new source of intense gamma-radiation in the sky

 

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Analyzing the data collected by the Fermi Gamma-ray Space Telescope Maxim Pshirkov (The Sternberg Astronomical Institute, MSU) discovered a new source that confirmed the fact that binary systems with strong colliding stellar winds comprise a separate new population of high-energy gamma-ray sources. His article was published in the latest issue of 'Monthly Notices of the Royal Astronomical Society Letters':http://dx.doi.org/10.1093/mnrasl/slv205

 

Massive binary star systems with highly luminous and hot Wolf-Rayet stars and massive (tens solar masses) OB companion generate strong stellar winds. Its percussion may lead to producing a fierce photon flux with an energetic potential of more than a hundred mega electronvolt (MEV), when a distance separating stars is relatively short. That phenomenon was considered as a possible source of gamma-radiation for a long while.

 

Strong stellar winds are generated in the binary systems consisting of highly luminous and hot Wolf-Rayet stars and massive ( several tens solar masses) OB companions. Wind collision may produce strong photon emission with photon energies exceeding hundred mega electronvolts (MeV). This phenomenon was considered as a possible source of gamma-radiation for a long while.

 

Though such radiation was detected only once, with the famous Eta Carinae, which was observed for more than four centuries (particularly intensively - after 1834, when one of its stars underwebt an explosion and for some time was the most luminous star in the sky) ). Eta Carinae is comparatively close to Earth - around 7,5 -- 8 thousand light years. The stars in this system weight 120 and (30-80) solar masses respectively, and shine brighter than millions of suns. If they were 10 parsec (30 light years) away from the Earth, they would be just as luminous as the Moon, while the Sun would be invisible on such distance. Naturally, Eta Carinae was the first candidate to consider and seven years ago high-energy radiation from this system was finally detected.

 

However, one example was not enough to confirm the model of binary stars emitting high-energy radiation, and the search for similar sources was continued, which turned out to be a tricky task.

 

"Recent calculations proved such star types as Eta Carinae to be incredibly rare - probably, one per a galaxy like we inhabit, or less,' said Maxim Pshirkov, my colleagues' research resulted in no certain findings. In 2013 an American-Austrian research team composed a list of seven stellar systems containing Wolf-Rayet stars, where a radiation could most probably appear. This research was based on two years of observations and lacked data, so it was only possible to set an upper limit on the HE radiation. I decided toutilize larger set of data seven years of Fermi-LAT observations. As the result - it was discovered that Gamma Velorum is the source of gamma-radiation at 6.σ. confidence level"

 

This system contains two stars with masses of 30 and 10 solar masses. Their orbital parameters are well-studied and they are separated by about the same distance as Earth and Sun. The luminosity of this binary system is about 200 thousand times higher than of the Sun and strong stellar winds have very high mass loss rate: hundred-thousandth and two ten-millionth of the solar mass every year . Though these figures seem to be small, actually this amount is huge, particularly comparing to the solar wind which only amounts to 10-14 solar mass per annum As the stellar winds in the Gamma Velorum system collide on a speed exceeding 1000 kilometers per second, particles are accelerated in the shock. Though an exact mechanism of this acceleration is still unknown, it definitely leads to a high energy photon radiation that turned out to be detected by Fermi LAT.

 

An attentive reader who followed the process of searching for Higgs boson in the Large Hadron Collider has probably faced the standard deviation that Pshirkov mentions and remembered that in physics a hypothesis is proved on a statistical accuracy higher than 5σ. That means it is confirmed with a probability higher than 99,999%. In other words Pshirkov's discovery with its six standard deviations is definitely reliable, though it's still not far away from the threshold. According to the article, it was partly a pure luck that helped the researcher.

 

"Searching for similar sources in the very galactic plane is much more complicated, since it is a powerful gamma-ray source itself, and detecting small photon excess coming from colliding stellar winds becomes much more difficult with this background," says the scientist. "But the Gamma Velorum system lies above the plane surface and it is comparatively close to us. The discovery would not probably happen, if it was further away or closer to the plane."

http://www.eurekalert.org/pub_releases/2016-02/lmsu-afm021716.php

 

Eta Carinae

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

 

Wolf–Rayet star

https://en.wikipedia.org/wiki/Wolf%E2%80%93Rayet_star

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LOC    989

WR binary systems continue to amaze me. WR type stars in general amaze me. :)

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Unobscured Vision    2,651

Eta Carinae and Betelgeuse are my two favorite stars. That whole Carinae Nebula Complex is a good one. :yes: 

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LOC    989

I used to have a Betelgeuse poster in my room when I was a youngen :D And no, not a movie poster with Michael Keaton :p

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Draggendrop    5,747

Our Suns Size Compared To Other Star Sizes

video is 1:10 min.

 

 

 

 

Top 10 largest stars ever discovered

video is 4:24 min.

 

 

 

:)

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