CASTRO Simulations reveal an unusual death for ancient stars

This image is a slice through the interior of a supermassive star of 55,500 solar masses along the axis of symmetry. 

It shows the inner helium core in which nuclear burning is converting helium to oxygen, powering various fluid instabilities (swirling lines). 

This "snapshot" from a CASTRO simulation shows one moment a day after the onset of the explosion, when the radius of the outer circle would be slightly larger than that of the orbit of the Earth around the sun. 

Visualizations were done in VisIT. 

Credit: Ken Chen, University of California at Santa Cruz

Certain primordial stars, those 55,000 and 56,000 times the mass of our Sun, or solar masses, may have died unusually.

In death, these objects, among the Universe's first-generation of stars, would have exploded as supernovae and burned completely, leaving no remnant black hole behind.

Astrophysicists at the University of California, Santa Cruz (UCSC) and the University of Minnesota came to this conclusion after running a number of supercomputer simulations at the US Department of Energy's (DOE's) National Energy Research Scientific Computing Center (NERSC) and Minnesota Supercomputing Institute at the University of Minnesota.

They relied extensively on CASTRO, a compressible astrophysics code developed at DOE's Lawrence Berkeley National Laboratory's (Berkeley Lab's) Computational Research Division (CRD).

Their findings were recently published in Astrophysical Journal (ApJ).

First-generation stars are especially interesting because they produced the first heavy elements, or chemical elements other than hydrogen and helium.

In death, they sent their chemical creations into outer space, paving the way for subsequent generations of stars, solar systems and galaxies.

With a greater understanding of how these first stars died, scientists hope to glean some insights about how the Universe, as we know it today, came to be.

"We found that there is a narrow window where supermassive stars could explode completely instead of becoming a supermassive black hole, no one has ever found this mechanism before," says Ke-Jung Chen, a postdoctoral researcher at UCSC and lead author of the ApJ paper.

"Without NERSC resources, it would have taken us a lot longer to reach this result."

"From a user perspective, the facility is run very efficiently and it is an extremely convenient place to do science."

More information: Astrophysical Journal, iopscience.iop.org/0004-637X/790/2/162

Hints of gravitational waves found in the stars

Energetic events, such as this artist’s rendition of a binary-star merger, are thought to create gravitational waves that cause ripples in space and time. 

 Credit: NASA

Scientists have shown how gravitational waves, invisible ripples in the fabric of space and time that propagate through the universe, might be "seen" by looking at the stars.

The new model proposes that a star that oscillates at the same frequency as a gravitational wave will absorb energy from that wave and brighten, an overlooked prediction of Einstein's 1916 theory of general relativity.

The study, which was published today in the Monthly Notices of the Royal Astronomical Society: Letters, contradicts previous assumptions about the behavior of gravitational waves.

"It's pretty cool that a hundred years after Einstein proposed this theory, we're still finding hidden gems," said Barry McKernan, a research associate in the Museum's Department of Astrophysics, who is also a professor at CUNY's Borough of Manhattan Community College; a faculty member at CUNY's Graduate Center; and a Kavli Scholar at the Kavli Institute for Theoretical Physics.

Gravitational waves can be thought of like the sound waves emitted after an earthquake, but the source of the "tremors" in space are energetic events like supernovae (exploding stars), binary neutron stars (pairs of burned-out cores left behind when stars explode), or the mergers of black holes and neutron stars.

Although scientists have long known about the existence of gravitational waves, they've never made direct observations but are attempting to do so through experiments on the ground and in space.

Part of the reason why detection is difficult is because the waves interact so weakly with matter but McKernan and his colleagues from CUNY, the Harvard-Smithsonian Center for Astrophysics, the Institute for Advanced Study, and Columbia University, suggest that gravitational waves could have more of an effect on matter than previously thought.

The new model shows that stars with oscillations, vibrations, that match the frequency of gravitational waves passing through them can resonate and absorb a large amount of energy from the ripples.

"It's like if you have a spring that's vibrating at a particular frequency and you hit it at the same frequency, you'll make the oscillation stronger," McKernan said. "The same thing applies with gravitational waves."

If these stars absorb a large pulse of energy, they can be "pumped up" temporarily and made brighter than normal while they discharge the energy over time.

This could provide scientists with another way to detect gravitational waves indirectly.

"You can think of stars as bars on a xylophone, they all have a different natural oscillation frequency," said co-author Saavik Ford, who is a research associate in the Museum's Department of Astrophysics as well as a professor at the Borough of Manhattan Community College, CUNY; a faculty member at CUNY's Graduate Center; and a Kavli Scholar at the Kavli Institute for Theoretical Physics.

"If you have two black holes merging with each other and emitting gravitational waves at a certain frequency, you're only going to hit one of the bars on the xylophone at a time but because the black holes decay as they come closer together, the frequency of the gravitational waves changes and you'll hit a sequence of notes. So you'll likely see the big stars lighting up first followed by smaller and smaller ones."

The work also presents a different way to indirectly detect gravitational waves. From the perspective of a gravitational wave detector on Earth or in space, when a star at the right frequency passes in front of an energetic source such as merging black holes, the detector will see a drop in the intensity of gravitational waves measured."

"In other words, stars, including our own Sun, can eclipse background sources of gravitational waves.

"You usually think of stars as being eclipsed by something, not the other way around," McKernan said.

The researchers will continue to study these predictions and try to determine how long it would take to observe these effects from a telescope or detector.

More Information:
B. McKernan, K.E.S. Ford, B. Kocsis, Z. Haiman. "Stars as resonant absorbers of gravitational waves." Monthly Notices of the Royal Astronomical Society: Letters, 2014 - arxiv.org/abs/1405.1414

Fluorine formed in stars and our Sun

The Sun by the Atmospheric Imaging Assembly of NASA's Solar Dynamics Observatory. Credit: NASA

The fluorine that is found in products such as toothpaste was likely formed billions of years ago in now dead stars of the same type as our sun.

This has been shown by astronomers at Lund University in Sweden, together with colleagues from Ireland and the USA.

Fluorine can be found in everyday products such as toothpaste and fluorine chewing gum.

However, the origins of the chemical element have been somewhat of a mystery.

There have been three main theories about where it was created. The findings now presented support the theory that fluorine is formed in stars similar to the sun but heavier, towards the end of their existence.

The sun and the planets in our solar system have then been formed out of material from these dead stars.

Nils Ryde

"So, the fluorine in our toothpaste originates from the sun's dead ancestors", said Nils Ryde, a reader in astronomy at Lund University.

With doctoral student Henrik Jönsson and colleagues from Ireland and the US, he has studied stars formed at different points in the history of the universe to see if the amount of fluorine they contain agrees with the predictions of the theory.

By analysing the light emitted by a star, it is possible to calculate how much of different elements it contains. Light of a certain wavelength indicates a certain element.

In the present study, the researchers used a telescope on Hawaii and a new type of instrument that is sensitive to light with a wavelength in the middle of the infrared spectrum. It is in this area that the signal is found in this case.

"Constructing instruments that can measure infrared light with high resolution is very complicated and they have only recently become available", said Nils Ryde.

Different chemical elements are formed at high pressure and temperature inside a star.

Henrik Jönsson

Fluorine is formed towards the end of the star's life, when it has expanded to become what is known as a red giant. The fluorine then moves to the outer parts of the star.

After that, the star casts off the outer parts and forms a planetary nebula. The fluorine that is thrown out in this process mixes with the gas that surrounds the stars, known as the interstellar medium.

New stars and planets are then formed from the interstellar medium. When the new stars die, the interstellar medium is enriched once again.

The researchers are now also turning their attention to other types of stars.

Among other things, they will try to find out whether fluorine could have been produced in the early universe, before the first red giants had formed.

They will also use the same method to study environments in the universe that are different from the environment surrounding the sun, such as close to the supermassive black hole at the centre of the Milky Way.

There, the cycle of stars dying and new ones being born goes considerably faster than around the sun.

"By looking at the level of fluorine in the stars there, we can say whether the processes that form it are different", said Nils Ryde.

Pushy black holes stop elliptical galaxies from forming stars

Multi-wavelength view of the elliptical galaxy NGC 5044. Credit: Digitised Sky Survey /NASA Chandra /Southern Observatory for Astrophysical Research/Very Large Array. 

Contradicting past theories, cold gas has been found in abundance in some elliptical galaxies—showing that there must be some other explanation why these types of galaxies don't form new stars.

Astronomers believe that the jets from supermassive black holes in these galaxies' center must push around the gas and prevent stars from forming.

Researchers spotted the gas for the first time using old data from the recently retired Herschel space observatory, which was able to peer well into the infrared—where it spotted carbon ions and oxygen atoms.

This find stands against the previous belief that these galaxies were "red and dead", referring to their physical appearance and the fact that they form no new stars.

"We looked at eight giant elliptical galaxies that nobody had looked at with Herschel before and we were delighted to find that, contrary to previous belief, six out of eight abound with cold gas", stated Norbert Werner, a researcher at Stanford University in California who led the study.

"These galaxies are red, but with the giant black holes pumping in their hearts, they are definitely not dead," added Werner.

Previously, scientists thought that the galaxies got rid of their cold gas or had used it all up during a burst of earlier star formation.

With cold gas found in the majority of the sample, researchers then used other observatories to try to find warmer gas up to tens of millions of Kelvin (or Fahrenheit or Celsius).

NGC 1399, an elliptical galaxy about 65 million light years from Earth. Credit: NASA, Chandra

X-ray information from NASA's Chandra X-ray Observatory revealed that there is hot gas cooling in six of the eight galaxies, but not in the remaining two of the sample.

"This is consistent with theoretical expectations: once cooled, the hot gas would become the warm and cold gas that are observed at longer wavelengths.

However, in these galaxies the cooling process somehow stopped, and the cold gas failed to condense and form stars," the European Space Agency stated.

"While the six galaxies with plenty of cold gas harbour moderately active black holes at their centres," ESA added, "the other two show a marked difference."

"In the two galaxies without cold gas, the central black holes are accreting matter at frenzied pace, as confirmed by radio observations showing powerful jets of highly energetic particles that stem from their cores."

More information: N. Werner, J. B. R. Oonk, M. Sun, P. E. J. Nulsen, S. W. Allen, R. E. A. Canning, A. Simionescu, A. Hoffer, T. Connor, M. Donahue, A. C. Edge, A. C. Fabian, A. von der Linden, C. S. Reynolds, and M. Ruszkowski. "The origin of cold gas in giant elliptical galaxies and its role in fuelling radio-mode AGN feedback." MNRAS first published online February 24, 2014 DOI: 10.1093/mnras/stu006

Large Magellanic Cloud‎'s clockwork motion captured in nearby galaxy - Video

This photo illustration shows Hubble measurements of the rotation of the Large Magellanic Cloud (LMC), the nearest visible galaxy to our Milky Way. 

The LMC appears in the Southern Hemisphere's night sky. In this photo illustration, the image contrast in a ground-based photo was enhanced to highlight the LMC’s faint outer regions, which are not visible to the naked eye. 

To illustrate the LMC's large apparent size on the sky, an image of the full moon is shown at bottom right. A horizon has been added for perspective. 

The arrows represent the highest-quality Hubble measurements of the motion of the LMC's stars to show how this galaxy rotates. 

Each arrow reveals the predicted motion over the next 7 million years. The motion of each star measured by Hubble over a few years’ time is a million times smaller than the length of each arrow. 

The LMC completes a rotation every 250 million years. 

Credit: NASA, ESA, A. Feild and Z. Levay (STScI), Y. Beletsky (Las Campanas Observatory), and R. van der Marel (STScI)

Using the NASA /ESA Hubble Space Telescope, astronomers have for the first time precisely measured the rotation rate of a galaxy based on the clock-like movement of its stars.

According to their analysis, the central part of the neighboring galaxy, called the Large Magellanic Cloud (LMC), completes a rotation every 250 million years.

Coincidentally, it takes our Sun the same amount of time to complete a rotation around the center of our Milky Way galaxy.

Roeland van der Marel

The Hubble team, composed of Roeland van der Marel of the Space Telescope Science Institute (STSI) in Baltimore, Md., and Nitya Kallivayalil of the University of Virginia in Charlottesville, Va., used Hubble to measure the average motion of hundreds of individual stars in the LMC, located 170,000 light-years away.

Hubble recorded the stars' slight movements over a seven-year period.

Disk-shaped spiral galaxies, like the Milky Way and the LMC, generally rotate like a carousel.

Hubble's precision tracking offers a new way to determine a galaxy's rotation by the "sideways" proper motion of its stars, as seen in the plane of sky.

Astronomers have long measured the sideways motions of nearby celestial objects, but this is the first time that the precision has become sufficient to see another distant galaxy rotate.

For the past century astronomers have calculated galaxy rotation rates by observing a slight shift in the spectrum, called the Doppler effect, of its starlight.

On one side of a galaxy's spinning stellar disk, the stars swinging in the direction of Earth will show a spectral blueshift (the compression of light waves due to motion toward the observer).

Stars swinging away from Earth on the opposite side of a galaxy will show a spectral redshift (the stretching of light to redder wavelengths due to motion away from the observer).

The newly measured Hubble sideways motions and the Doppler motions measured previously each provide complementary information about the LMC's rotation rate. 

By combining the results, the Hubble team for the first time obtained a fully three-dimensional view of stellar motions in another galaxy.

This animation illustrates the rotation rate of the Large Magellanic Cloud (LMC). 

Hubble Space Telescope observations have determined that the central part of the LMC completes a rotation every 250 million years. 

Hence, it takes more than 10 million years for even the small amount of rotation illustrated here. 

Credit: NASA, ESA, and G. Bacon, R. van der Marel, A. Feild, L. Frattare, Z. Levay, and F. Summers (STScI)

"Determining a galaxy's rotation by measuring its instantaneous back and forth motions doesn't allow one to actually see things change over time," said van der Marel, the lead author on a paper in the Feb. 1 issue of the Astrophysical Journal describing and interpreting the results.

"By using Hubble to study the stars' motions over several years, we can actually for the first time see a galaxy rotate in the plane of the sky."

More Information: Third-epoch Magellanic Cloud Proper Motions. II. The Large Magellanic Cloud Rotation Field in Three Dimensions: Roeland P. van der Marel1 and Nitya Kallivayalil - iopscience.iop.org/0004-637X/781/2/121/article

NASA WISE: Coldest brown dwarfs blur lines between stars and planets

This artist's conception portrays a free-floating brown dwarf, or failed star. 

A new study shows that several of these objects are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit. 

Credit: NASA/JPL-Caltech

Astronomers are constantly on the hunt for ever-colder star-like bodies, and two years ago a new class of such objects was discovered by researchers using NASA's WISE space telescope.

However, until now no one has known exactly how cool their surfaces really are - some evidence suggested they could be room temperature.

A new study shows that while these brown dwarfs, sometimes called failed stars, are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit.

To reach such low surface temperatures after cooling for billions of years means that these objects can only have about 5 to 20 times the mass of Jupiter.

Unlike the Sun, these objects' only source of energy is from their gravitational contraction, which depends directly on their mass.

Trent Dupuy

"If one of these objects was found orbiting a star, there is a good chance that it would be called a planet," says Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics.

But because they probably formed on their own and not in a proto-planetary disk, astronomers still call these objects brown dwarfs even if they are "planetary mass."

Characterizing these cold brown dwarfs is challenging because they emit most of their light at infrared wavelengths, and they are very faint due to their small size and low temperature.

To get accurate temperatures, astronomers need to know the distances to these objects.

"We wanted to find out if they were colder, fainter, and nearby or if they were warmer, brighter, and more distant," explains Dupuy.

Using NASA's Spitzer Space Telescope, the team determined that the brown dwarfs in question are located at distances 20 to 50 light-years away.

Locations of brown dwarfs: The locations of brown dwarfs discovered by NASA's Wide-field Infrared Survey Explorer, or WISE, and mapped by NASA's Spitzer Space Telescope, are shown here in this diagram. 

The view is from a vantage point about 100 light-years away from the sun, looking back towards the constellation Orion. 

At this distance our sun is barely visible as a speck of light. The vastly fainter brown dwarfs would not even be visible in this view. The red lines all link back to the location of the sun. 

Credit: NASA/JPL-Caltech

To determine the distances to these objects the team measured their parallax - the apparent change in position against background stars over time.

As the Spitzer Space Telescope orbits the Sun its perspective changes and nearby objects appear to shift back and forth slightly.

The same effect occurs if you hold up a finger in front of your face and close one eye and then the other. The position of your finger seems to shift when viewed against the distant background.

The new data also present new puzzles to astronomers that study cool, planet-like atmospheres. Unlike warmer brown dwarfs and stars, the observable properties of these objects don't seem to correlate as strongly with temperature.

This suggests increased roles for other factors, such as convective mixing, in driving the chemistry at the surface.

This study examined the initial sample of the coldest brown dwarfs discovered in the WISE survey data.

Additional objects discovered in the past two years remain to be studied and will hopefully shed light on some of these outstanding issues.

NASA's WISE discover rare galaxy furiously burning fuel for stars

The tiny red spot in this image is one of the most efficient star-making galaxies ever observed, converting gas into stars at the maximum possible rate. 

The galaxy is shown here in an image from NASA's Wide-field Infrared Survey Explorer (WISE), which first spotted the rare galaxy in infrared light. 

Credit: NASA/JPL-Caltech/STScI/IRAM

Astronomers have found a galaxy turning gas into stars with almost 100 percent efficiency, a rare phase of galaxy evolution that is the most extreme yet observed.

The findings come from the IRAM Plateau de Bure interferometer in the French Alps, NASA's Wide-field Infrared Survey Explorer and NASA's Hubble Space Telescope.

Jim Geach

"Galaxies burn gas like a car engine burns fuel. Most galaxies have fairly inefficient engines, meaning they form stars from their stellar fuel tanks far below the maximum theoretical rate," said Jim Geach of McGill University, lead author of a new study appearing in the Astrophysical Journal Letters.

"This galaxy is like a highly tuned sports car, converting gas to stars at the most efficient rate thought to be possible," he said.

The galaxy, called SDSSJ1506+54, jumped out at the researchers when they looked at it using data from WISE's all-sky infrared survey. Infrared light is pouring out of the galaxy, equivalent to more than a thousand billion times the energy of our sun.

Ned Wright

"Because WISE scanned the entire sky, it detected rare galaxies like this one that stand out from the rest," said Ned Wright of UCLA, the WISE principal investigator.

Hubble's visible-light observations revealed that the galaxy is extremely compact, with most of its light emanating from a region just a few hundred light-years across.

"This galaxy is forming stars at a rate hundreds of times faster than our Milky Way galaxy, but the sharp vision of Hubble revealed that the majority of the galaxy's starlight is being emitted by a region just a few percent of the diameter of the Milky Way. This is star formation at its most extreme," said Geach.

The team then used the IRAM Plateau de Bure Interferometer to measure the amount of gas in the galaxy. The ground-based telescope detected millimeter-wave light coming from carbon monoxide, an indicator of the presence of hydrogen gas, which is fuel for stars.

Combining the rate of star formation derived with WISE, and the gas mass measured by IRAM, the scientists get a measure of the star formation efficiency.

The results reveal that the star-forming efficiency of the galaxy is close to the theoretical maximum, called the Eddington limit. In regions of galaxies where new stars are forming, parts of gas clouds are collapsing due to gravity. When the gas is dense enough to squeeze atoms together and ignite nuclear fusion, a star is born.

At the same time, winds and radiation from stars that have just formed can prevent the formation of new stars by exerting pressure on the surrounding gas, curtailing the collapse.

The Eddington limit is the point at which the force of gravity pulling gas together is balanced by the outward pressure from the stars. Above the Eddington limit, the gas clouds would be blown apart, halting star formation.

ESA's Herschel Space Observatory: Ancient Galaxy Producing Stars at Record Pace

Artist's impression of a starburst galaxy similar to the distant HFLS 3, which was churning out stars at a record-setting pace less than a billion years after the Big Bang.

CREDIT: ESA–C. Carreau

Astronomers peering into the early history of the universe have spotted perhaps the most productive star-forming galaxy ever found.

Known as HFLS 3, the young galaxy churns out about 3,000 new stars each year — more than 2,000 times as many as the Milky Way averages, and up to 20 times more than the number created by similar galaxies today.

The massive starburst galaxy existed only 880 million years after the Big Bang that created our universe 13.8 billion years ago, making HFLS 3 the most distant known pure starburst galaxy.

"One of the big surprises was how evolved this galaxy is in terms of its properties," stated principal investigator Dominik Riechers of Cornell University.

Dominik Riechers

Starburst galaxies exist today, burning through their stores of dust and gas to produce stars at a fantastic rate. But HFLS 3 is 15 to 20 times larger, and produces 15 to 20 times more stars, than similar current galaxies.

The difference is in the dust. Early in the history of the universe, when less dust had been converted to stars, galaxies such as HFLS 3 had access to more raw materials.

"The same processes are involved, but just 'supersized,'" Riechers said.

One of tens of thousands of early starburst galaxies detected by the European Space Agency's (ESA) Herschel Space Observatory, HFLS 3 attracted attention because it appeared very red among the rest, which indicated the possibility of greater distance.

Riechers and a team of international astronomers used a suite of instruments from around the world to study the distant structure.

"Finding this galaxy was like looking for a needle in a haystack," Riechers said.

Hobby-Eberley Telescope Discovery: First evidence planet's destruction by its star

The first evidence of a planet's destruction by its aging star has been discovered with the Hobby-Eberly Telescope by an international team of astronomers. 

A similar fate may await the inner planets in our solar system, when the sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now. 

Credit: Marty Harris/McDonald Obs./UT-Austin 

The first evidence of a planet's destruction by its aging star has been discovered by an international team of astronomers.

The evidence indicates that the missing planet was devoured as the star began expanding into a "red giant" -- the stellar equivalent of advanced age.

"A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now," said Alexander Wolszczan, Evan Pugh Professor of Astronomy and Astrophysics at Penn State University, who is one of the members of the research team.

Wolszczan also is the discoverer of the first planet ever found outside our solar system. The astronomers also discovered a massive planet in a surprisingly elliptical orbit around the same red-giant star, named BD+48 740, which is older than the Sun with a radius about eleven times bigger.

Wolszczan and the team's other members detected evidence of the missing planet's destruction while they were using the Hobby-Eberly Telescope to study the aging star and to search for planets around it.

The evidence includes the star's peculiar chemical composition, plus the highly unusual elliptical orbit of its surviving planet.

"Our detailed spectroscopic analysis reveals that this red-giant star, BD+48 740, contains an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago," Adamow said.

Lithium is easily destroyed in stars, which is why its abnormally high abundance in this older star is so unusual.

"Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars," Wolszczan added.

"In the case of BD+48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiraled into the star and heated it up while the star was digesting it."

The second piece of evidence discovered by the astronomers is the highly elliptical orbit of the star's newly discovered massive planet, which is at least 1.6 times as massive as Jupiter.

"We discovered that this planet revolves around the star in an orbit that is only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point," Niedzielski said.

"Such orbits are uncommon in planetary systems around evolved stars and, in fact, the BD+48 740 planet's orbit is the most elliptical one detected so far."

Because gravitational interactions between planets are responsible for such peculiar orbits, the astronomers suspect that the dive of the missing planet toward the star before it became a giant could have given the surviving massive planet a burst of energy, throwing it into an eccentric orbit like a boomerang.

"Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry," Villaver explained.

"The highly elongated orbit of the massive planet we discovered around this lithium-polluted red-giant star is exactly the kind of evidence that would point to the star's recent destruction of its now-missing planet."

The paper describing this discovery is posted in an early online edition of the Astrophysical Journal Letters (Adamow et al. 2012, ApJ, 754, L15).


Read the paper here Astrophysical Journal

NASA Hubble Wide Field Image: M107 - A Field of Stars

Image credit: ESA/NASA

The Hubble Space Telescope captured a crowd of stars that looks rather like a stadium darkened before a show, lit only by the flashbulbs of the audience’s cameras.

Yet the many stars of this object, known as Messier 107, are not a fleeting phenomenon, at least by human reckoning of time -- these ancient stars have gleamed for many billions of years.

Messier 107 is one of more than 150 globular star clusters found around the disc of the Milky Way galaxy. These spherical collections each contain hundreds of thousands of extremely old stars and are among the oldest objects in the Milky Way. The origin of globular clusters and their impact on galactic evolution remains somewhat unclear, so astronomers continue to study them.

Messier 107 can be found in the constellation of Ophiuchus (The Serpent Bearer) and is located about 20,000 light-years from our solar system.

French astronomer Pierre Méchain first noted the object in 1782, and British astronomer William Herschel documented it independently a year later. A Canadian astronomer, Helen Sawyer Hogg, added Messier 107 to Charles Messier's famous astronomical catalogue in 1947.

This picture was obtained with the Wide Field Camera of Hubble’s Advanced Camera for Surveys.

Milky Way's Galactic Gobbling Leaves Star 'Crumbs'

Artist's concept of the four tails of the Sagittarius dwarf galaxy (orange clump on left of the image) orbiting the Milky Way.

The bright yellow circle to the right of the Milky Way's center is our sun (not to scale). We can see the Sagittarius galaxy's star tails stretching across the sky.

CREDIT: Amanda Smith, Institute of Astronomy, University of Cambridge

Our Milky Way galaxy is a messy eater, leaving streams of star "crumbs" spread across the sky after chomping its smaller neighbors, a new study reports.

Astronomers have found two such streams emanating from the Sagittarius dwarf galaxy, torn off by the Milky Way's huge gravitational pull.

The two newfound star tails are in the southern galactic hemisphere, and they meet up with two others previously known from Sagittarius in the northern galactic hemisphere.

"Sagittarius is like a beast with four tails," study co-author Wyn Evans, of the University of Cambridge in the United Kingdom, said in a statement.

Astromers Discovery: Some Ancient Stars Have Huge Heavy Metal Deposits

A new study revealed that some ancient stars in the outer reaches of the Milky Way were found to have an unusually large amounts of heavy metals like gold, platinum and uranium.

This discovery has puzzled astronomers as it is the younger generations of stars that typically have an abundance of heavy metals, scientists said.

Researchers tried to unravel the mystery by observing these ancient stars for several years using the European Southern Observatory's fleet of telescopes in Chile, training the telescopes on 17 "abnormal" stars in the Milky Way that were found to be rich in the heaviest chemical elements.

"In the outer parts of the Milky Way there are old 'stellar fossils' from our own galaxy's childhood," the study's lead author Terese Hansen, an astrophysicist at the Niels Bohr Institute at the University of Copenhagen.

"These old stars lie in a halo above and below the galaxy's flat disc. In a small percentage - approximately 1-to-2 percent of these primitive stars - you find abnormal quantities of the heaviest elements relative to iron and other 'normal' heavy elements."

According to the researchers, there are two possible theories to explain these discoveries about ancient stars and both are about supernova explosions.

One theory focuses on the formation of the first stars shortly after the universe was created. The universe then was dominated by light elements like hydrogen and helium and the first stars were formed as clouds of these gasses gathered and collapsed under their own gravity.

The hydrogen and helium in the stars then merged together and formed the first heavy elements like carbon, nitrogen and oxygen.

Supernova explosions cause these stars to die, and the newly formed elements are spread as gas clouds into space, which eventually formed into new stars containing heavier elements.

This process have made the newer generations of stars more abundant with heavy elements.

A second theory is that early supernovas disperse these elements in different directions, which eventually formed some of the stars in the Milky Way. This explains how many of the old stars became abnormally rich in heavy elements, the researchers said.

"In the supernova explosion the heavy elements like gold, platinum and uranium are formed and when the jets hit the surrounding gas clouds, they will be enriched with the elements and form stars that are incredibly rich in heavy elements," Hansen said.

The study was published in the Astrophysical Journal Letters.

NASA's Hubble Observes Young Dwarf Galaxies Bursting With Stars

This image reveals 18 tiny galaxies uncovered by NASA's Hubble Space Telescope. 

The puny galaxies, shown in the postage stamp-sized images, existed 9 billion years ago and are brimming with star birth. 

Hubble's Wide Field Camera 3 and Advanced Camera for Surveys spied the galaxies in a field called the Great Observatories Origins Deep Survey (GOODS). 

The galaxies are among 69 dwarf galaxies found in the GOODS (marked by green circles in the large image) and other fields.

Images of the individual galaxies were taken November 2010 to January 2011.
 

The large image was taken between Sept. 2002 and Dec. 2004, and between Sept. 2009 and Oct. 2009. 

(Credit: NASA, ESA, A. van der Wel (Max Planck Institute for Astronomy, Heidelberg, Germany), H. Ferguson and A. Koekemoer (STScI.), and the CANDELS team)

NASA Spitzer Image: Swirling Landscape of North America Nebula

This swirling landscape of stars is known as the North America Nebula. It is seen here in Visible Light Spectrum.
.

In visible light above, the region resembles North America, but in this infrared view from NASA's Spitzer Space Telescope, the continent disappears.

Where did the continent go? The reason you don't see it in Spitzer's view has to do, in part, with the fact that infrared light can penetrate dust whereas visible light cannot. 

Dusty, dark clouds in the visible image become transparent in Spitzer's view. 

In addition, Spitzer's infrared detectors pick up the glow of dusty cocoons enveloping baby stars.

Clusters of young stars (about one million years old) can be found throughout the image. Some areas of this nebula are still very thick with dust and appear dark even in Spitzer's view.

The Spitzer image contains data from both its infrared array camera and multi-band imaging photometer. 

Light with a wavelength of 3.6 microns has been colour-coded blue; 4.5-micron light is blue-green; 5.8-micron and 8.0-micron light are green; and 24-micron light is red. This image is from February 2011.

Image Credit: NASA/JPL-Caltech

'Pacman Nebula' Lives the High Life

High-mass stars are important because they are responsible for much of the energy pumped into our galaxy over its lifetime.

Unfortunately, these stars are poorly understood because they are often found relatively far away and can be obscured by gas and dust.

The star cluster NGC 281 is an exception to this rule.

It is located about 9,200 light years from Earth and, remarkably, almost 1,000 light years above the plane of the Galaxy, giving astronomers a nearly unfettered view of the star formation within it.

NGC 281 is known informally as the "Pacman Nebula" because of its appearance in optical images. In optical images the "mouth" of the Pacman character appears dark because of obscuration by dust and gas, but in the infrared Spitzer image the dust in this region glows brightly.

Image Credits: X-ray: NASA/CXC/CfA/S.Wolk; IR: NASA/JPL/CfA/S.Wolk

Bizarre real time face-substitution system demonstrated

Faces from arturo castro on Vimeo.

Some day in the not-too-distant future, you may be on a service like Chatroulette, and suddenly find yourself matched up with a person who looks exactly like Angelina Jolie.

Well, chances are it won't really be her. Instead, it will likely be someone using the descendant of a system put together by Arturo Castro. Using a combination of existing software, the Barcelona digital artist has demonstrated how a variety of famous faces can be mapped onto his own, moving with it in real time.

While Castro's system isn't likely to fool anyone - in its present version - it's an unsettling indication of what could be possible with just a little more finessing.

Castro's application was created using openFrameworks, an open source framework for creative coding. This was combined with FaceTracker, which produces a virtual mesh that matches a human subject's facial features.

The colours of the famous faces were blended with those of Arturo's own using an image clone code developed by artist Kevin Atkinson. Finally, the FaceTracker meshes were wrapped around his face using the ofxFaceTracker add-on for openFrameworks.

The resulting video, which can be seen below, alternates between being funny and just plain creepy, with Castro taking on the identities of celebrities such as Marilyn Monroe, Michael Jackson and Paris Hilton.

Face Substitution from Kyle McDonald on Vimeo.

Fighting Dragons of Ara

Fighting Dragons of Ara (NGC 6188 and 6164) by Michael Sidoni.

Clouds of swirling purple, green and orange gas and dust that appear as ‘fighting dragons’, shaped by the recent birth of large stars much bigger and brighter than our Sun.

One such star can be seen to the lower left of the image within two shells of glowing gas.

The image gives a snapshot of the chaotic stellar nurseries in which stars are born.

Our own Sun probably formed in similar circumstances 4.5 billion years ago.

Picture: Michael Sidonio

ATLAS3D project: Replacing the handle of Hubble's tuning fork

Since Edwin Hubble introduced his famous tuning fork diagram more than 70 years ago, spiral galaxies and early-type galaxies have been regarded as being two distinct families.

The spirals are characterised by the presence of disks of stars and gas in rapid rotation, while the early-types are gas poor and described as spheroid systems, with less rotation and often non-axisymmetric shapes.

A team of 25 astronomers from Europe and Northern America, including ASTRON astronomers Morganti, Oosterloo, and Serra, has shown that many galaxies, which are normally classified as spheroid galaxies according to the 70 year old Hubble classification scheme, are in fact spiral galaxies.

The so-called ATLAS3D team observed a sample of 260 galaxies with the SAURON spectrograph on the 4.2-meter William Herschel Telescope on La Palma, which allowed them to determine the movements of the stars in these carefully selected galaxies. The results are important because it gives astronomers more information about the way galaxies form.

The team proposed a revised scheme in which the vast majority of spheroid galaxies, also known as early-type galaxies, are close relatives of spiral galaxies and for this reason form a parallel sequence to them.

The new paradigm highlights a much closer connection between early-type and spiral galaxies than previously thought, and this will need to be considered in future models of how galaxies form.

The above results were presented in three ATLAS3D team papers which will appear this month on the journal Monthly Notices of the Royal Astronomical Society.

NASA WISE: Galaxy Menagerie

A new, colourful collection of galaxy specimens has been released by NASA's Wide-field Infrared Survey Explorer, or WISE, mission. 

It showcases galaxies of several types, from elegant grand design spirals to more patchy flocculent spirals.

Some of the galaxies have roundish centers, while others have elongated central bars. 

The orientation of the galaxies varies as well, with some seeming to peer straight back at us in the face-on configuration while others point to the side, appearing edge-on. 

Infrared light has been translated into colours we see with our eyes, such that the shortest wavelengths are blue and the longest are red. 

The oldest stars appear blue, while pockets of newly formed stars have yellow or reddish hues. Below is more information about each member of WISE's galaxy collection. The order is from top left to right; middle left to right; and bottom left to right.

The Whirpool Galaxy, or Messier 51 (M51)

Known by astronomers as M51, this beauty is a grand design spiral, which are galaxies with well-defined spiral arms. Its smaller companion, a dwarf galaxy called NGC 5195, is thought to have helped define and shape the arms due to its gravitational "dance" with its larger partner. 

M51 is also known as "The Lord Ross Galaxy," after the astronomer who was the first to study its spiral structure in the 1840s. It is located 25 million light-years away in the constellation Canes Venatici, and is 81,000 light-years across.

Bode's Galaxy, or Messier 81 (M81)

M81 is another grand design spiral galaxy, with pronounced arms spiraling into its core. WISE highlights areas where gas and dust have been compressed in the arms, leading to the formation of new stars. 

This compression has been enhanced by the galaxy's interaction with its partner galaxy, Messier 82 (not pictured here). That galaxy is bursting with new stars, and is therefore known as a "starburst." M81 is 12 million light-years away in the constellation Ursa Major, and 94,000 light-years across.

Southern Pinwheel Galaxy, or Messier 83 (M83)
At about 55,500 light-years across, M83 is s a bit more than half the size of our Milky Way Galaxy, but it has a similar overall structure. Like the Milky Way, most of M83's stars, dust, and gas lie in a thin disk decorated with grand spiral arms.

This galaxy is classified as a barred spiral because, in addition to a central bulge of stars, it has a central bar-shaped region of stars. It is 15 million light-years away in the constellation Hydra.

NGC 628, or Messier 74 (M74)

Some astronomers call the grand design spiral Messier 74 the "perfect spiral," for its exceptional symmetry. It is suspected to have a black hole at its center, with a mass equal to 10,000 suns. 

It is one of only a handful of known black holes with masses intermediate between the relatively smaller ones that form from collapsing stars and the supermassive black holes millions of times more massive than the sun. 

Supermassive black holes are more typically found at the centers of galaxies. Messier 74 is located between 24.5 and 36 million light-years away in the constellation Pisces, and is 100,000 light-years across.

NGC 1398

This barred spiral has a dense inner ring that surrounds a bright, central core. The ring is actually two spiral arms that are closed in on each other. In contrast to its well-defined center, this galaxy's arms are patchy, or flocculent.

It is inclined about 43 degrees away from an edge-on orientation, and has a diameter of 135,000 light-years. NGC 1398 is 65 million light-years away in the Fornax constellation, and is part of the Fornax cluster of galaxies.

NGC 2403

This fuzzy-looking galaxy is a flocculent, or patchy, spiral. It is largely veiled by gas and dust at visible-light wavelengths, but when viewed with WISE, its arms are clearly revealed. 

In 2004, NGC 2403 was host to one of the largest supernova in recent decades -- SN 2004dj was first observed in 2004 in Japan and was visible for 8 months. NGC 2403 is located 11.4 million-light years away in the constellation Camelopardalis, and is about 73,000 light-years across.

Splinter or Knife Edge Galaxy, or NGC 5907

This galaxy's face is angled about 90 degrees from our view, so it appears edge-on and thin as a splinter, or knife. It was discovered by the astronomer William Herschel in 1788. 

There is a large complex of stellar streams surrounding the galaxy, which can't be seen in the WISE image. These are the torn-up shreds of smaller galaxies that were consumed. 

The faint green hue seen in the WISE composite is due to the "halo" of old stars that encircles the central region of the galaxy. The Splinter Galaxy is about 53 million light-years away in the constellation Draco, and is nearly 200,000 light-years across.

Barnard's Galaxy, or IC 4895 or NGC 6822

Barnard's Galaxy is known as a dwarf for its small size -- it has only about one percent of the mass of the Milky Way. The galaxy's irregular shape is dominated by a central bar of stars, whose appearance resembles that of the nearby satellite galaxy, the Large Magellanic Cloud. 

It is therefore given a classification of "Magellanic type." The prominent yellow blobs seen against the blue stellar background are sites of recent star formation. Barnard's Galaxy is 1.6 million light-years away in the Sagittarius constellation, and is about 7,000 light-years across.

Hidden Galaxy, or IC342

Sometimes called the Hidden Galaxy, this spiral beauty is shrouded behind our own galaxy, the Milky Way. Stargazers and professional astronomers have a hard time seeing the galaxy through the Milky Way's bright band of stars, dust and gas. 

WISE's infrared vision cuts through this veil, offering a crisp view. The nucleus is very bright at infrared wavelengths, due to a burst of new stars forming there. The Hidden Galaxy is located about 10 million light-years away in the constellation Camelopardalis, and is 62,000 light-years across.

The colours used in all of these image represent specific wavelengths of infrared light. Blue and cyan represent 3.4- and 4.6-micron light, mainly emitted by hot stars. Green and red represent 12- and 22-micron wavelengths, primarily light emitted from warm dust.

Image Credit: NASA/JPL-Caltech/WISE Team

Clouds and Stars over Cotopaxi Volcano in Ecuador

Explanation: What's happening above the Cotopaxi volcano in Ecuador? Quite a bit, from the looks of the above one-night, time-lapse movie, taken earlier this month. The majestic volcano is first seen through breaks in fast moving clouds as the movie begins.

Soon the clouds have dissipated and a sky filled with stars seems to rotate about the snow-peaked volcano's peak. The band of our Milky Way Galaxy, the dark Coal Sack nebula, and the Southern Cross can all be seen overhead.

Satellites steak by from several directions. Soon thin clouds roll by and seem to make the brightest stars sparkle. On the volcano (starting at about 1:13 of the movie), the lights of climbers flash.

Near the end of the movie, a bright airplane passes over the peak with a residual trail seen drifting away.