Universe News (miscellaneous articles)

[LOC Veteran]

54 minutes ago, Draggendrop said:

Just an opinion, but I think it will be way past 2050.....we've been stuck in LEO for 45 years...not a confidence building regime.    

True, and the way things are going with science here in the US (leaving politics out of things) currently is certainly distressing sadly. Other countries will pick up the slack and surpass us I'm sure at some point unless we return to our 60s way of thinking etc.

[Draggendrop Veteran]

Star clusters discovery could upset the astronomical applecart

 

Quote

he discovery of young stars in old star clusters could send scientists back to the drawing board for one of the Universe's most common objects.

Dr Bi-Qing For, from the International Centre for Radio Astronomy Research in Perth, said our understanding of how stars evolve is a cornerstone of astronomical science.

 

"There are a billion trillion stars in the Universe and we've been observing and classifying those we can see for more than a century," she said.

"Our models of stellar evolution are based on the assumption that stars within star clusters formed from the same material at roughly the same time."

 

A star cluster is a group of stars that share a common origin and are held together by gravity for some length of time.

 

Because star clusters are assumed to contain stars of similar age and composition researchers have used them as an "astronomical laboratory" to understand how mass affects the evolution of stars.

 

"If this assumption turns out to be incorrect, as our findings suggest, then these important models will need to be revisited and revised," Dr For said.

The discovery, published today in the Monthly Notices of the Royal Astronomical Society, involves a study of star clusters located in the Large Magellanic Cloud, a neighbouring galaxy to the Milky Way.

 

By cross-matching the locations of several thousand young stars with the locations of stellar clusters, the researchers found 15 stellar candidates that were much younger than other stars within the same cluster.

 

"The formation of these younger stars could have been fuelled by gas entering the clusters from interstellar space," said co-author Dr Kenji Bekki, also from the International Centre for Radio Astronomy Research.

 

"But we eliminated this possibility using observations made by radio telescopes to show that there was no correlation between interstellar hydrogen gas and the location of the clusters we were studying.

 

"We believe the younger stars have actually been created out of the matter ejected from older stars as they die, which would mean we have discovered multiple generations of stars belonging to the same cluster."

 

Dr Bekki said the stars were currently too faint to see using optical telescopes because of the dust that surrounds them.

"They have been observed using infrared wavelengths by orbiting space telescopes Spitzer and Herschel, operated by NASA and the European Space Agency," he said.

 

"An envelope of gas and dust surrounds these young stars but as they become more massive and this shroud blows away, they will become visible at optical wavelengths for powerful instruments like the Hubble Space Telescope."

 

"If we point Hubble at the clusters we've been studying, we should be able to see both young and old stars and confirm once and for all that star clusters can contain several generations of stars."

https://www.eurekalert.org/pub_releases/2017-03/icfr-scd030517.php

 

 

This vibrant image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.
CREDIT
Credit: NASA/JPL-Caltech/M. Meixner (STScI) & the SAGE Legacy Team.

 

 

 

This image from NASA's Spitzer Space Telescope features the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy. Overlaying the image are circles showing the locations of 15 star clusters where multiple generations of stars have been discovered.
CREDIT
Credit: Karl Gordon and Margaret Meixner - Space Telescope Science Institute/AURA/NASA. Compilation by Bi-Qing For and Kenji Bekki (ICRAR/UWA).

 

 

 

Left: This image from NASA's Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy. Overlaying the image are the locations of 15 star clusters where multiple generations of stars have been discovered. Right: A closer view of four of the star clusters where young stellar objects have been detected. The crosses mark the locations of young stars and the squares in the main image show the locations of these four clusters.
CREDIT
Credit: Karl Gordon and Margaret Meixner - Space Telescope Science Institute/AURA/NASA. Compilation by Bi-Qing For and Kenji Bekki (ICRAR/UWA).

 

 

icrar home page

 

Monthly Notices, Royal Astronomical Society

[Draggendrop Veteran]

Last minute addition, just thought this looked great....

 

Astronomy Picture of the Day

2017 March 7 

 

UGC 12591: The Fastest Rotating Galaxy Known 
Image Credit: NASA, ESA, Hubble

 

Quote

Explanation: Why does this galaxy spin so fast? To start, even identifying which type of galaxy UGC 12591 is difficult -- it has dark dust lanes like a spiral galaxy but a large diffuse bulge of stars like a lenticular. Surprisingly observations show that UGC 12591 spins at about 480 km/sec, almost twice as fast as our Milky Way, and the fastest rotation rate yet measured. The mass needed to hold together a galaxy spinning this fast is several times the mass of our Milky Way Galaxy. Progenitor scenarios for UGC 12591 include slow growth by accreting ambient matter, or rapid growth through a recent galaxy collision or collisions -- future observations may tell. The light we see today from UGC 12591 left about 400 million light years ago, when trees were first developing on Earth.

https://apod.nasa.gov/apod/ap170307.html

 

[Unobscured Vision]

Goodies!  Can't wait for JWST to observe that area of formation to see what's going on. Thanks DD!

 

And 12591 is a looker ... a pin-up, even.  

[Draggendrop Veteran]

Hubble Dates Black Hole’s Last Big Meal

 

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For the supermassive black hole at the center of our Milky Way galaxy, it's been a long time between dinners. NASA's Hubble Space Telescope has found that the black hole ate its last big meal about 6 million years ago, when it consumed a large clump of infalling gas. After the meal, the engorged black hole burped out a colossal bubble of gas weighing the equivalent of millions of suns, which now billows above and below our galaxy's center.

The immense structures, dubbed the Fermi Bubbles, were first discovered in 2010 by NASA's Fermi Gamma-ray Space Telescope. But recent Hubble observations of the northern bubble have helped astronomers determine a more accurate age for the bubbles and how they came to be.

 

"For the first time, we have traced the motion of cool gas throughout one of the bubbles, which allowed us to map the velocity of the gas and calculate when the bubbles formed," said lead researcher Rongmon Bordoloi of the Massachusetts Institute of Technology in Cambridge. "What we find is that a very strong, energetic event happened 6 million to 9 million years ago. It may have been a cloud of gas flowing into the black hole, which fired off jets of matter, forming the twin lobes of hot gas seen in X-ray and gamma-ray observations. Ever since then, the black hole has just been eating snacks."

 

The new study is a follow-on to previous Hubble observations that placed the age of the bubbles at 2 million years old.

 

A black hole is a dense, compact region of space with a gravitational field so intense that neither matter nor light can escape. The supermassive black hole at the center of our galaxy has compressed the mass of 4.5 million sun-like stars into a very small region of space.

 

Material that gets too close to a black hole is caught in its powerful gravity and swirls around the compact powerhouse until it eventually falls in. Some of the matter, however, gets so hot it escapes along the black hole's spin axis, creating an outflow that extends far above and below the plane of a galaxy.

 

The team's conclusions are based on observations by Hubble's Cosmic Origins Spectrograph (COS), which analyzed ultraviolet light from 47 distant quasars. Quasars are bright cores of distant active galaxies.

 

Imprinted on the quasars' light as it passes through the Milky Way bubble is information about the speed, composition, and temperature of the gas inside the expanding bubble.

 

The COS observations measured the temperature of the gas in the bubble at approximately 17,700 degrees Fahrenheit. Even at those sizzling temperatures, this gas is much cooler than most of the super-hot gas in the outflow, which is 18 million degrees Fahrenheit, seen in gamma rays. The cooler gas seen by COS could be interstellar gas from our galaxy's disk that is being swept up and entrained into the super-hot outflow. COS also identified silicon and carbon as two of the elements being swept up in the gaseous cloud. These common elements are found in most galaxies and represent the fossil remnants of stellar evolution.

 

The cool gas is racing through the bubble at 2 million miles per hour. By mapping the motion of the gas throughout the structure, the astronomers estimated that the minimum mass of the entrained cool gas in both bubbles is equivalent to 2 million suns. The edge of the northern bubble extends 23,000 light-years above the galaxy.

 

"We have traced the outflows of other galaxies, but we have never been able to actually map the motion of the gas," Bordoloi said. "The only reason we could do it here is because we are inside the Milky Way. This vantage point gives us a front-row seat to map out the kinematic structure of the Milky Way outflow."

 

The new COS observations build and expand on the findings of a 2015 Hubble study by the same team, in which astronomers analyzed the light from one quasar that pierced the base of the bubble.

more at the link...

https://www.nasa.gov/feature/goddard/2017/hubble-dates-black-holes-last-big-meal

 

Hubble dates black hole's last big meal

https://www.eurekalert.org/pub_releases/2017-03/nsfc-hdb030917.php

 

and from 2015

 

Hubble Discovers That Milky Way Core Drives Wind at 2 Million Miles Per Hour

https://www.nasa.gov/content/goddard/hubble-discovers-that-milky-way-core-drives-wind-at-2-million-miles-per-hour

 

 

 

The light of several distant quasars pierces the northern half of the Fermi Bubbles - an outflow of gas expelled by our Milky Way galaxy's hefty black hole. Bottom left: the measurement of gas moving toward and away from Earth, indicating the material is traveling at a high velocity. Hubble also observed light from quasars that passed outside the northern bubble. Upper right: the gas in one such quasar's light path is not moving toward or away from Earth. This gas is in the disk of the Milky Way and does not share the same characteristics as the material probed inside the bubble.

Credits: NASA, ESA, and Z. Levy (STScI)

 

[DocM]

 

[DocM]

Iridium update

 

 

[DocM]

And here we go,

 

Assuming SLS survives, they place 2 hardshell habitats in either the near rectilinear or a distant retrograde lunar orbit, both very stable. ISS partners have been discussing this as a next step, with the US preferring the near rectilinear lunar orbit.  

 

Anatoly Zak of RussianSpaceWeb did a write-up on the Planetary Society site.

 

http://www.planetary.org/blogs/guest-blogs/2017/20170309-nasa-iss-partners-cislunar-station.html

 

 

 

[Draggendrop Veteran]

Star Discovered in Closest Known Orbit Around Likely Black Hole

 

Artist's illustration of a star found in the closest orbit known around a black hole in the globular cluster named 47 Tucanae.

Credits: X-ray: NASA/CXC/University of Alberta/A.Bahramian et al.; Illustration: NASA/CXC/M.Weiss

 

Quote

Astronomers have found evidence for a star that whips around a black hole about twice an hour. This may be the tightest orbital dance ever witnessed for a likely black hole and a companion star.

 

This discovery was made using NASA’s Chandra X-ray Observatory as well as NASA’s NuSTAR and CSIRO’s Australia Telescope Compact Array (ATCA). 

The close-in stellar couple – known as a binary – is located in the globular cluster 47 Tucanae, a dense cluster of stars in our galaxy about 14,800 light years from Earth.

 

While astronomers have observed this binary for many years, it wasn’t until 2015 that radio observations with the ATCA revealed the pair likely contains a black hole pulling material from a companion star called a white dwarf, a low-mass star that has exhausted most or all of its nuclear fuel.

 

New Chandra data of this system, known as X9, show that it changes in X-ray brightness in the same manner every 28 minutes, which is likely the length of time it takes the companion star to make one complete orbit around the black hole. Chandra data also shows evidence for large amounts of oxygen in the system, a characteristic feature of white dwarfs. A strong case can, therefore, be made that the companion star is a white dwarf, which would then be orbiting the black hole at only about 2.5 times the separation between the Earth and the Moon.

 

“This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in,” said first author Arash Bahramian of the University of Alberta in Edmonton, Canada, and Michigan State University in East Lansing. “Luckily for this star, we don’t think it will follow this path into oblivion, but instead will stay in orbit.

 

Although the white dwarf does not appear to be in danger of falling in or being torn apart by the black hole, its fate is uncertain.

 

“Eventually so much matter may be pulled away from the white dwarf that it ends up only having the mass of a planet,” said co-author Craig Heinke, also of the University of Alberta. “If it keeps losing mass, the white dwarf may completely evaporate.

 

How did the black hole get such a close companion? One possibility is that the black hole smashed into a red giant star, and then gas from the outer regions of the star was ejected from the binary. The remaining core of the red giant would form into a white dwarf, which becomes a binary companion to the black hole. The orbit of the binary would then have shrunk as gravitational waves were emitted, until the black hole started pulling material from the white dwarf.

 

The gravitational waves currently being produced by the binary have a frequency that is too low to be detected with Laser Interferometer Gravitational-Wave Observatory, LIGO, that has recently detected gravitational waves from merging black holes. Sources like X9 could potentially be detected with future gravitational wave observatories in space.

 

An alternative explanation for the observations is that the white dwarf is partnered with a neutron star, rather than a black hole. In this scenario, the neutron star spins faster as it pulls material from a companion star via a disk, a process that can lead to the neutron star spinning around its axis thousands of times every second. A few such objects, called transitional millisecond pulsars, have been observed near the end of this spinning up phase. The authors do not favor this possibility as transitional millisecond pulsars have properties not seen in X9, such as extreme variability at X-ray and radio wavelengths. However, they cannot disprove this explanation.

 

“We’re going to watch this binary closely in the future, since we know little about how such an extreme system should behave”, said co-author Vlad Tudor of Curtin University and the International Centre for Radio Astronomy Research in Perth, Australia. “We’re also going to keep studying globular clusters in our galaxy to see if more evidence for very tight black hole binaries can be found.

 

A paper describing these results was recently accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available online.

https://www.nasa.gov/mission_pages/chandra/news/star-discovered-in-closest-known-orbit-around-likely-black-hole.html

 

The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9

https://arxiv.org/abs/1702.02167

 

 

[Draggendrop Veteran]

Astronomy Picture of the Day

 

The Cone Nebula from Hubble 
Image Credit: Hubble Legacy Archive, NASA, ESA - Processing & Licence: Judy Schmidt

 

Quote

Explanation: Stars are forming in the gigantic dust pillar called the Cone Nebula. Cones, pillars, and majestic flowing shapes abound in stellar nurseries where natal clouds of gas and dust are buffeted by energetic winds from newborn stars. The Cone Nebula, a well-known example, lies within the bright galactic star-forming region NGC 2264. The Cone was captured in unprecedented detail in this close-up composite of several observations from the Earth-orbiting Hubble Space Telescope.

 

While the Cone Nebula, about 2,500 light-years away in Monoceros, is around 7 light-years long, the region pictured here surrounding the cone's blunted head is a mere 2.5 light-years across. In our neck of the galaxy that distance is just over half way from our Sun to its nearest stellar neighbors in the Alpha Centauri star system. The massive star NGC 2264 IRS, seen by Hubble's infrared camera in 1997, is the likely source of the wind sculpting the Cone Nebula and lies off the top of the image. The Cone Nebula's reddish veil is produced by glowing hydrogen gas.

https://apod.nasa.gov/apod/ap170315.html

[Draggendrop Veteran]

Astronomers observe a dying red giant star's final act

 

This is a molecular gas around star LL Pegasi.
CREDIT
ALMA, Hyosun Kim

 

Quote

An international team of astronomers has observed a striking spiral pattern in the gas surrounding a red giant star named LL Pegasi and its companion star 3,400 light-years from Earth, using a powerful telescope in northern Chile called Atacama Large Millimeter/submillimeter Array, or ALMA.

 

"What we are seeing in splendid detail with these observations is the final act of a dying red giant star, as it sheds most of its gaseous bulk in a strong, outflowing wind," said study co-author Mark Morris, UCLA professor of physics and astronomy.

 

After comparing their telescopic observations with computer simulations, the astronomers concluded that a highly elliptical orbit is responsible for the shape of the gaseous emissions surrounding this system.

 

The research appears in the journal Nature Astronomy and is the cover story of the March issue.

 

"Because of the orbital motion of the mass-losing red giant, the cold molecular gas constituting the wind from that star is being spun out like the sprays of water from a rotating garden sprinkler, forming the outflowing pattern of spiral shells," Morris said.

 

ALMA, a powerful international facility operated cooperatively by many countries around the world including the United States, measures extremely short wavelength radio emission. Using this unique instrument, the scientists were able to create a three-dimensional image of the emission from molecules ejected from LL Pegasi and which then form a spiral pattern caused by the presence of the orbiting companion star.

 

The images, which show many complete revolutions of the spiral pattern, offer clues about the dynamics of the binary system over a period of 5,000 years.

 

"This unusually ordered system opens the door to understanding how the orbits of such systems evolve with time as one of the stars loses most of its mass," Morris said.

https://www.eurekalert.org/pub_releases/2017-03/uoc--aoa031617.php

 

Visualizing the ALMA image cube of LL Pegasi

video is 0:58 min.

 

Quote

Each frame of the video shows the molecular gas emission from LL Pegasi for a different line-of-sight velocity.  It starts with the gas moving towards us, and ends with the gas moving away from us.  The field size is 20,000 times the distance between the Sun and the Earth. Credit: ALMA (ESO/NAOJ/NRAO)/Hyosun Kim et al. in Nature Astronomy.

 

 

 

 

3-D visualization of the molecular gas material surrounding LL Pegasi

video is 6 sec

 

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Image of LL Pegasi, first as it appears to the Hubble Space Telescope, and then as it appears in the emission from molecules, as observed with ALMA. The numerical model appears beside the nebula, and both the model and the image are rotated to display the excellent three-dimensional agreement.

 

 

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

 

Astronomy Picture of the Day

 

JWST: Ghosts and Mirrors 
Image Credit: Chris Gunn, NASA

 

Quote

Explanation: Ghosts aren't actually hovering over the James Webb Space Telescope. But the lights are out as it stands with gold tinted mirror segments and support structures folded in Goddard Space Flight Center's Spacecraft Systems Development and Integration Facility clean room. Following vibration and acoustic testing, bright flashlights and ultraviolet lights are played over the stationary telescope looking for contamination, easier to spot in a darkened room. In the dimness the camera's long exposure creates the ghostly apparitions, blurring the moving lights and engineers. A scientific successor to Hubble, the James Webb Space Telescope is optimized for the infrared exploration of the early Universe. Its planned launch is in 2018 from French Guiana on a European Space Agency Ariane 5 rocket.

https://apod.nasa.gov/apod/ap170318.html

 

[DocM]

 

[T3X4S]

On 4/8/2016 at 9:58 PM, warwagon said:

 

Bare with me, I just got home after having 5 Vodka diet cokes and 2 beers!  Be kind!

OK - now with a Carl Sagan-ish spin.

Warwagon - I think if anyone can do a Carl Sagan impression, it would be you.  My latest audiobook was Armada, read by Wil Wheaton.   In the book, Carl Sagan read a excerpt, I think you could do better than Wil Wheaton's impression. 

[+Warwagon MVC]

3 minutes ago, T3X4S said:

OK - now with a Carl Sagan-ish spin.

Warwagon - I think if anyone can do a Carl Sagan impression, it would be you.  My latest audiobook was Armada, read by Wil Wheaton.   In the book, Carl Sagan read a excerpt, I think you could do better than Wil Wheaton's impression. 

 

 

You'll have to hook me up. You'll also have to listen to my sober version too!

[+Warwagon MVC]

24 minutes ago, T3X4S said:

OK - now with a Carl Sagan-ish spin.

Warwagon - I think if anyone can do a Carl Sagan impression, it would be you.  My latest audiobook was Armada, read by Wil Wheaton.   In the book, Carl Sagan read a excerpt, I think you could do better than Wil Wheaton's impression. 

 

 

 

@T3X4S

[Draggendrop Veteran]

Universe's ultraviolet background could provide clues about missing galaxies

 

Universe's ultraviolet background could help unravel missing galaxies

video is 0:49 min.

 

 

This movie follows the formation of galaxies with cosmic time, illustrating how ultraviolet (UV) radiation from other galaxies and from quasars suppresses the formation of stars inside small galaxies near to large galaxies similar to the Milky Way and Andromeda. The left panel shows a simulation that includes such diffuse UV radiation as in the real universe, where fewer smaller galaxies form. For comparison, the right panel shows what would happen in the absence of such radiation, with more small galaxies forming.
CREDIT
S. McAlpine/S. Berry

 

Quote

Astronomers have developed a way to detect the ultraviolet (UV) background of the Universe, which could help explain why there are so few small galaxies in the cosmos.

 

UV radiation is invisible but shows up as visible red light when it interacts with gas.

 

An international team of researchers led by Durham University, UK, has now found a way to measure it using instruments on Earth.

 

The researchers said their method can be used to measure the evolution of the UV background through cosmic time, mapping how and when it suppresses the formation of small galaxies.

 

The study could also help produce more accurate computer simulations of the evolution of the Universe.

 

The findings are published today (Wednesday, 22 March) in the journal Monthly Notices of the Royal Astronomical Society.

 

UV radiation - a type of radiation also given out by our Sun - is found throughout the Universe and strips smaller galaxies of the gas that forms stars, effectively stunting their growth.

 

It is believed to be the reason why some larger galaxies like our Milky Way don't have many smaller companion galaxies.

 

Simulations show that there should be more small galaxies in the Universe, but UV radiation essentially stopped them from developing by depriving them of the gas they need to form stars.

 

Larger galaxies like the Milky Way were able to withstand this cosmic blast because of the thick gas clouds surrounding them.

 

Lead author Dr Michele Fumagalli, in the Institute for Computational Cosmology and Centre for Extragalactic Astronomy, at Durham University, said: "Massive stars and supermassive black holes produce huge amounts of ultraviolet radiation, and their combined radiation builds-up this ultraviolet background.

 

"This UV radiation excites the gas in the Universe, causing it to emit red light in a similar way that the gas inside a fluorescent bulb is excited to produce visible light.

 

"Our research means we now have the ability to measure and map this UV radiation which will help us to further refine models of galaxy formation."

 

Co-author Professor Simon Morris, in the Centre for Extragalactic Astronomy, Durham University, added: "Ultimately this could help us learn more about the evolution of the Universe and why there are so few small galaxies."

 

Researchers pointed the Multi Unit Spectroscopic Explorer (MUSE), an instrument of the European Southern Observatory's Very-Large Telescope, in Chile, at the galaxy UGC 7321, which lies at a distance of 30 million light years from Earth.

 

MUSE provides a spectrum, or band of colours, for each pixel in the image allowing the researchers to map the red light produced by the UV radiation illuminating the gas in that galaxy.

 

The research, funded in the UK by the Science and Technology Facilities Council, could also help scientists predict the temperature of the cosmic gas with more accuracy.

 

Co-author Professor Tom Theuns, in Durham University's Institute for Computational Cosmology, said: "Ultraviolet radiation heats the cosmic gas to temperatures higher than that of the surface of the Sun.

 

"Such hot gas will not cool to make stars in small galaxies. This explains why there are so few small galaxies in the Universe, and also why our Milky Way has so few small satellite galaxies."

https://www.eurekalert.org/pub_releases/2017-03/du-uub032017.php

 

 

Colour image of the starlight emitted by a nearby spiral galaxy called UGC 7321. Stars in this galaxy lie in a disc, similar to that of our galaxy, the Milky Way. We see this disc nearly perfectly edge-on. Other sources in the image are foreground or background objects (galaxies and stars), unrelated to galaxy UGC 7321.
CREDIT
Credit: M. Fumagalli/T. Theuns/S. Berry

 

 

Galaxy UGC 7321 is surrounded by hydrogen gas, and as this gas is irradiated with UV radiation, it emits a diffuse red glow through a process known as fluorescence. This image shows the light emitted by stars inside the galaxy, surrounded by a red ring that represents the fluorescent emission induced by the UV radiation.

CREDIT

M. Fumagalli/T. Theuns/S. Berry

 

Paper...

A measurement of the z = 0 UV background from Hα fluorescence

https://academic.oup.com/mnras/article/467/4/4802/3001962/A-measurement-of-the-z-0-UV-background-from-H

 

[Draggendrop Veteran]

Astronomers identify purest, most massive brown dwarf

 

 

An artist's impression of the new pure and massive brown dwarf.
CREDIT
John Pinfield

 

Quote

An international team of astronomers has identified a record breaking brown dwarf (a star too small for nuclear fusion) with the 'purest' composition and the highest mass yet known. The object, known as SDSS J0104+1535, is a member of the so-called halo - the outermost reaches - of our Galaxy, made up of the most ancient stars. The scientists report the discovery in Monthly Notices of the Royal Astronomical Society.

 

Brown dwarfs are intermediate between planets and fully-fledged stars. Their mass is too small for full nuclear fusion of hydrogen to helium (with a consequent release of energy) to take place, but they are usually significantly more massive than planets.

 

Located 750 light years away in the constellation of Pisces, SDSS J0104+1535 is made of gas that is around 250 times purer than the Sun, so consists of more than 99.99% hydrogen and helium.

 

Estimated to have formed about 10 billion years ago, measurements also suggest it has a mass equivalent to 90 times that of Jupiter, making it the most massive brown dwarf found to date.

 

It was previously not known if brown dwarfs could form from such primordial gas, and the discovery points the way to a larger undiscovered population of extremely pure brown dwarfs from our Galaxy's ancient past.

 

The research team was led by Dr ZengHua Zhang of the Institute of Astrophysics in the Canary Islands. He said: "We really didn't expect to see brown dwarfs that are this pure. Having found one though often suggests a much larger hitherto undiscovered population - I'd be very surprised if there aren't many more similar objects out there waiting to be found."

 

SDSS J0104+1535 has been classified as an L type ultra-subdwarf using its optical and near-infrared spectrum, measured using the European Southern Observatory's "Very Large Telescope" (VLT). This classification was based on a scheme very recently established by Dr Zhang.

https://www.eurekalert.org/pub_releases/2017-03/ras-aip032417.php

 

papers...

 

Primeval very low-mass stars and brown dwarfs – II. The most metal-poor substellar object

https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx350

 

Primeval very low-mass stars and brown dwarfs - II. The most metal-poor substellar object

https://arxiv.org/abs/1702.02001

 

[Unobscured Vision]

Oooh ... right on the edge, in more ways than one. Thanks DD.  

[Draggendrop Veteran]

Villanova University Astronomers Part of Team That Reveals Secret (X-Ray) Lives of Cepheids: The Surprising Discovery of a New Class of Pulsating X-Ray Stars

 

Quote

VILLANOVA, Pa. – A surprising new class of X-ray pulsating variable stars has been discovered by a team of American and Canadian astronomers led by Villanova University’s Scott Engle and Edward Guinan.  Part of the Villanova Secret Lives of Cepheids program, the new X-ray observations, obtained by NASA's Chandra X-ray Observatory and published Thursday, March 23rd in The Astrophysical Journal, reveal that the bright prototype of Classical Cepheids, d Cephei, is a periodic pulsed X-ray source.

 

Research team members sharing in the discovery included Graham Harper, University of Colorado; Nancy Remage Evans, Harvard Center for Astrophysics; Manfred Cuntz, University of Texas, Arlington; and Hilding Neilson, University of Toronto.

 

The prototype star after which all Cepheids are named, d Cephei (d Cep) is, at a distance of 890 light years away, also one of the closest of its type. Cepheids are a famous class of pulsating variable stars and among the most astronomically important objects in the Universe. By measuring the pulsation periods and brightness of Cepheids astrophysicists can measure distances to other galaxies and calibrate the extragalactic distance scale. Cepheids also play an increasingly vital role in the effort to precisely measure the expansion rate of the Universe and to resolve the developing Hubble discrepancy.

 

Data recently returned for d Cep from the Chandra X-ray Observatory, combined with previous X-ray measures secured with the XMM-Newton X-ray satellite, have shown that d Cep has X-ray variations occurring in accord with the supergiant star's 5.4 day pulsation period. X-rays are observed at all phases of the star’s pulsations, but sharply rise by ~400% near the times when the star swells to its maximum diameter of about 45 times that of the Sun.

 

“Our first X-ray observations of Cepheids were made in 2006, and our first detections were met with a good bit of skepticism. The notion that Cepheids could be X-ray active seemed far-fetched because these stars are only a few times more massive and a little hotter than the Sun,” said Engle. “Over a decade later, we’ve finally shown that they can in fact be X-ray variable, but the work is far from over. Now we need to understand just how they generate and modulate their X-ray emissions, and what effect this could have on the Leavitt Period-Luminosity Law.”

 

d Cep is a bright star, easily seen without a telescope to the North in the constellation Cepheus. This yellow supergiant star, whose optical brightness variations were discovered in 1784, was one of the first variable stars known. Its light variations are the result of radial pulsations, in which the star contracts and expands with the same 5.4 day period as its brightness variations. The surface of d Cep reaches supersonic speeds of about 82,000 miles per hour, while the star shrinks and grows by roughly 2 million miles during each pulsation period. Thousands of Cepheids have been found in our galaxy as well as in other galaxies hundreds of millions of light years away.

 

Analyses of the X-ray data indicate the unexpected presence of very hot plasmas in d Cep, with temperatures above 10 million degrees Celsius. It is not certain yet whether the X-rays arise from pulsation-induced shock waves in the star’s dynamic atmosphere, or from the generation of a stellar magnetic field that becomes tangled, emitting X-rays. Other Cepheids are being studied to understand the source of the heated, X-ray emitting plasmas. At least two additional Cepheids show potential X-ray variability.

 

The research team led by Engle and Guinan previously used the Hubble Space Telescope to study ultraviolet emission lines from d Cep and other Cepheids. These emission lines originate in plasmas of up to 300,000 degrees Celsius; cooler than X-ray emitting plasmas but still far hotter than the surfaces of the stars. The ultraviolet emissions also vary in accord with the Cepheids’ pulsation periods but sharply rise after the Cepheid reaches minimum radius, as opposed to the X-ray emissions which peak just after maximum radius. The team is still studying exactly why the ultraviolet and X-ray emissions peak at such different phases of the star’s pulsations.

 

“Classical Cepheid stars are considered to be the most important variable stars in the sky. These pulsating supergiant stars have been used since the mid-1920s by Edwin Hubble and other astronomers to measure the distances to galaxies and determine the expansion rate of the universe,” said Guinan. “After many tries, the failure to detect X-rays from Cepheids during the 1980-90s led astronomers to give up on them as potential X-ray stars. So it was a big (but pleasant) surprise to find X-ray emission from d Cep and several other Cepheids.”

 

This discovery of X-rays for d Cep and some other Cepheids is the newest in a list of recently discovered Cepheid properties. These include circumstellar gas and dusty environments, infrared excesses, ultraviolet emission lines, and cycle-to-cycle variations in the stars’ periodic light changes. This combination of discoveries shows that Cepheids, after more than two centuries of study, still have their secrets. Given the astrophysical and cosmological importance of Cepheids, and the high precisions required to test cosmological models, these new discoveries should be better understood. X-ray observations of other bright Cepheids are planned to unravel their X-ray behavior.

http://www1.villanova.edu/villanova/media/pressreleases/2017/0323.html

 

 

NASA X-Ray Image of Cepheids

 

 

Delta Curves

 

[Jim K Global Moderator]

Quote

A mysterious flash of X-rays has been discovered by NASA’s Chandra X-ray Observatory in the deepest X-ray image ever obtained. This source likely comes from some sort of destructive event, but may be of a variety that scientists have never seen before.

 

 

The X-ray source, located in a region of the sky known as the Chandra Deep Field-South (CDF-S), has remarkable properties. Prior to October 2014, this source was not detected in X-rays, but then it erupted and became at least a factor of 1,000 brighter in a few hours. After about a day, the source had faded completely below the sensitivity of Chandra.

 

Thousands of hours of legacy data from the Hubble and Spitzer Space Telescopes helped determine that the event likely came from a faint, small galaxy about 10.7 billion light years from Earth. For a few minutes, the X-ray source produced a thousand times more energy than all the stars in this galaxy.

 

“Ever since discovering this source, we’ve been struggling to understand its origin,” said Franz Bauer of the Pontifical Catholic University of Chile in Santiago, Chile. “It’s like we have a jigsaw puzzle but we don’t have all of the pieces.”

 

Two of the three main possibilities to explain the X-ray source invoke gamma-ray burst (GRB) events. GRBs are jetted explosions triggered either by the collapse of a massive star or by the merger of a neutron star with another neutron star or a black hole. If the jet is pointing towards the Earth, a burst of gamma rays is detected. As the jet expands, it loses energy and produces weaker, more isotropic radiation at X-ray and other wavelengths.

 

Possible explanations for the CDF-S X-ray source, according to the researchers, are a GRB that is not pointed toward Earth, or a GRB that lies beyond the small galaxy. A third possibility is that a medium-sized black hole shredded a white dwarf star.

“None of these ideas fits the data perfectly,” said co-author Ezequiel Treister, also of the Pontifical Catholic University, “but then again, we’ve rarely if ever seen any of the proposed possibilities in actual data, so we don’t understand them well at all.”

 

The mysterious X-ray source was not seen at any other time during the two and a half months of exposure time Chandra has observed the CDF-S region, which has been spread out over the past 17 years. Moreover, no similar events have yet to be found in Chandra observations of other parts of the sky.

 

This X-ray source in the CDF-S has different properties from the as yet unexplained variable X-ray sources discovered in the elliptical galaxies NGC 5128 and NGC 4636 by Jimmy Irwin and collaborators. In particular, the CDF-S source is likely associated with the destruction of a neutron star, white dwarf, or massive star, and is roughly 100,000 times more luminous in X-rays. It is also located in a much smaller and younger host galaxy, and is only detected during a single, several-hour burst.

 

“We may have observed a completely new type of cataclysmic event,” said co-author Kevin Schawinski, of ETH Zurich in Switzerland. “Whatever it is, a lot more observations are needed to work out what we’re seeing.”

 

Additional highly targeted searches through the Chandra archive and those of ESA’s XMM-Newton and NASA’s Swift satellite may uncover more examples of this type of variable object that have until now gone unnoticed. Future X-ray observations by Chandra and other X-ray telescopes may also reveal the same phenomenon from other objects.

 

If the X-ray source was caused by a GRB triggered by the merger of a neutron star with a black hole or another neutron star, then gravitational waves would also have been produced. If such an event were to occur much closer to Earth, within a few hundred million light years, it may be detectable with the Laser Interferometer Gravitational-Wave Observatory (LIGO).

 

A paper describing this result appears in the June 2017 issue of the Monthly Notices of the Royal Astronomical Society and is available online. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

 

NASA

[LOC Veteran]

Yeah was reading about that eruption a couple days ago. Saw headlines like "BIGGEST EXPLOSION IN THE UNIVERSE EVER" all over the news sites about it. I truly wonder what caused it, I would assume a black hole collision/merger of some sort. But who knows. Plenty we don't know about the Universe

[DocM]

Destruct sequence 1, Code 1-1A

Destruct sequence 2, Code 1-1A-2B

Destruct sequence 3, Code 1-B-2B-3

Code Zero, Zero, Zero, Destruct, Zero

[LOC Veteran]

Not gonna lie DocM, I actually thought of that when I read the original story a few days ago

[Jim K Global Moderator]

 

Quote

Collapsing Star Gives Birth to a Black Hole

 

Astronomers have watched as a massive, dying star was likely reborn as a black hole. It took the combined power of the Large Binocular Telescope (LBT), and NASA's Hubble and Spitzer space telescopes to go looking for remnants of the vanquished star, only to find that it disappeared out of sight.

 

It went out with a whimper instead of a bang.

 

The star, which was 25 times as massive as our sun, should have exploded in a very bright supernova. Instead, it fizzled out—and then left behind a black hole.

 

 

"Massive fails" like this one in a nearby galaxy could explain why astronomers rarely see supernovae from the most massive stars, said Christopher Kochanek, professor of astronomy at The Ohio State University and the Ohio Eminent Scholar in Observational Cosmology.

 

As many as 30 percent of such stars, it seems, may quietly collapse into black holes — no supernova required.

 

"The typical view is that a star can form a black hole only after it goes supernova," Kochanek explained. "If a star can fall short of a supernova and still make a black hole, that would help to explain why we don’t see supernovae from the most massive stars."

 

He leads a team of astronomers who published their latest results in the Monthly Notices of the Royal Astronomical Society.

 

Among the galaxies they've been watching is NGC 6946, a spiral galaxy 22 million light-years away that is nicknamed the "Fireworks Galaxy" because supernovae frequently happen there — indeed, SN 2017eaw, discovered on May 14th, is shining near maximum brightness now. Starting in 2009, one particular star, named N6946-BH1, began to brighten weakly. By 2015, it appeared to have winked out of existence.

 

After the LBT survey for failed supernovas turned up the star, astronomers aimed the Hubble and Spitzer space telescopes to see if it was still there but merely dimmed. They also used Spitzer to search for any infrared radiation emanating from the spot. That would have been a sign that the star was still present, but perhaps just hidden behind a dust cloud.

 

All the tests came up negative. The star was no longer there. By a careful process of elimination, the researchers eventually concluded that the star must have become a black hole.

 

This pair of visible-light and near-infrared Hubble Space Telescope photos shows the giant star N6946-BH1 before and after it vanished out of sight by imploding to form a black hole. The left image shows the 25 solar mass star as it looked in 2007. In 2009, the star shot up in brightness to become over 1 million times more luminous than our sun for several months. But then it seemed to vanish, as seen in the right panel image from 2015. A small amount of infrared light has been detected from where the star used to be. This radiation probably comes from debris falling onto a black hole. The black hole is located 22 million light-years away in the spiral galaxy NGC 6946.

 

It's too early in the project to know for sure how often stars experience massive fails, but Scott Adams, a former Ohio State student who recently earned his doctorate doing this work, was able to make a preliminary estimate.

 

"N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey. During this period, six normal supernovae have occurred within the galaxies we've been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae," he said.

 

"This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way."

 

To study co-author Krzysztof Stanek, the really interesting part of the discovery is the implications it holds for the origins of very massive black holes — the kind that the LIGO experiment detected via gravitational waves. (LIGO is the Laser Interferometer Gravitational-Wave Observatory.)

 

It doesn't necessarily make sense, said Stanek, professor of astronomy at Ohio State, that a massive star could undergo a supernova — a process which entails blowing off much of its outer layers — and still have enough mass left over to form a massive black hole on the scale of those that LIGO detected.

 

"I suspect it's much easier to make a very massive black hole if there is no supernova," he concluded.

 

Adams is now an astrophysicist at Caltech. Other co-authors were Ohio State doctoral student Jill Gerke and University of Oklahoma astronomer Xinyu Dai. Their research was supported by the National Science Foundation.

 

NASA's Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington, D.C. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

 

The Large Binocular Telescope is an international collaboration among institutions in the United Sates, Italy and Germany.

 

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

 

Related Links:

• The science paper by S. Adams et al.
• NASA's Hubble Portal
• NASA's Spitzer Portal
• Caltech's Spitzer Portal
• Ohio State University's Release

NASA

[Unobscured Vision]

More Trappist-1 news ...  

 

Astrophysicists identify composition of earth-size planets in TRAPPIST-1 system

Article link | Phys.org website

 

Quote

The lighter green indicates optimistic regions of the habitable zone and the darker green denotes more conservative limits. Credit: University of Oklahoma
 

A University of Oklahoma post-doctoral astrophysics researcher, Billy Quarles, has identified the possible compositions of the seven planets in the TRAPPIST-1 system. Using thousands of numerical simulations to identify the planets stable for millions of years, Quarles concluded that six of the seven planets are consistent with an Earth-like composition. The exception is TRAPPIST-1f, which has a mass of 25 percent water, suggesting that TRAPPIST-1e may be the best candidate for future habitability studies.

TRAPPIST-1f has the tightest constraints with 25 percent of its mass in water, which is rare given its radius. The concern of this planet is that the mass is 70 percent the mass of the Earth, but it is the same size as the Earth. Because the radius is so large, the pressure turns the water to steam, and it is likely too hot for life as we know it. The search for planets with a composition as close to Earth's as possible is key for finding places that we could identify as being habitable. Quarles said he is continually learning about the planets and will investigate them further in his studies.

(Read more at the article link, above.)

Ooooooohhh ....  We've got a winner here, folks.