Posted on by Tammy Plotner

SOFIA Reveals Star-Forming Region W40

This mid-infrared image of the W40 star-forming region of the Milky Way galaxy was captured recently by the FORCAST instrument on the 100-inch telescope aboard the SOFIA flying observatory. (NASA / FORCAST image)

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Around 1957 light years away, a dense molecular cloud resides beside an OB star cluster locked in a massive HII region. The hydrogen envelope is slowly beginning to billow out and separate itself from the molecular gas, but we’re not able to get a clear picture of the situation thanks to interfering dust. However, by engaging NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), we’re now able to take one of the highest resolution mid-infrared looks into the heart of an incredible star-forming region known as W40 so far known to science.

Onboard a modified 747SP airliner, the Faint Object infraRed Camera for the SOFIA Telescope (FORCAST) has been hard at work utilizing its 2.5 meter (100″) reflecting telescope to capture data. The composite image shown above was taken at wavelengths of 5.4, 24.2 and 34.8 microns. Why this range? Thanks to the high flying SOFIA telescope, we’re able to clear Earth’s atmosphere and “get above” the ambient water vapor which blocks the view. Not even the highest based terrestrial telescope can escape it – but FORCAST can!

With about 1/10 the UV flux of the Orion Nebula, region W40 has long been of scientific interest because it is one of the nearest massive star-forming regions known. While some of its OB stars have been well observed at a variety of wavelengths, a great deal of the lower mass stars remain to be explored. But there’s just one problem… the dust hides their information. Thanks to FORCAST, astronomers are able to peer through the obscuration at W40’s center to examine the luminous nebula, scores of neophyte stars and at least six giants which tip the scales at six to twenty times more massive than the Sun.

Why is studying a region like W40 important to science? Because at least half of the Milky Way’s stellar population formed in similar massive clusters, it is possible the Solar System also “developed in such a cluster almost 5 billion years ago”. The stars FORCAST measures aren’t very bright and intervening dust makes them even more dim. But no worries, because this type of study cuts them out of dust that’s only carrying a temperature of a few hundred degrees. All that from a flying observatory!

Now, that’s cool…

Original Story Source: NASA/SOFIA News. For Further Reading: The W40 Cloud Complex and A Chandra Observation of the Obscured Star-Forming Complex W40.

Posted on by Ray Sanders

Are Pulsars Giant Permanent Magnets?

The Vela Pulsar, a neutron star corpse left from a titanic stellar supernova explosion, shoots through space powered by a jet emitted from one of the neutron star's rotational poles. Now a counter jet in front of the neutron star has been imaged by the Chandra X-ray observatory. The Chandra image above shows the Vela Pulsar as a bright white spot in the middle of the picture, surrounded by hot gas shown in yellow and orange. The counter jet can be seen wiggling from the hot gas in the upper right. Chandra has been studying this jet so long that it's been able to create a movie of the jet's motion. The jet moves through space like a firehose, wiggling to the left and right and up and down, but staying collimated: the "hose" around the stream is, in this case, composed of a tightly bound magnetic field. Image Credit:

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Some of the most bizarre phenomena in the universe are neutron stars. Very few things in our universe can rival the density in these remnants of supernova explosions. Neutron stars emit intense radiation from their magnetic poles, and when a neutron star is aligned such that these “beams” of radiation point in Earth’s direction, we can detect the pulses, and refer to said neutron star as a pulsar.

What has been a mystery so far, is how exactly the magnetic fields of pulsars form and behave. Researchers had believed that the magnetic fields form from the rotation of charged particles, and as such should align with the rotational axis of the neutron star. Based on observational data, researchers know this is not the case.

Seeking to unravel this mystery, Johan Hansson and Anna Ponga (Lulea University of Technology, Sweden) have written a paper which outlines a new theory on how the magnetic fields of neutron stars form. Hansson and Ponga theorize that not only can the movement of charged particles form a magnetic field, but also the alignment of the magnetic fields of components that make up the neutron star – similar to the process of forming ferromagnets.

Getting into the physics of Hansson and Ponga’s paper, they suggest that when a neutron star forms, neutron magnetic moments become aligned. The alignment is thought to occur due to it being the lowest energy configuration of the nuclear forces. Basically, once the alignment occurs, the magnetic field of a neutron star is locked in place. This phenomenon essentially makes a neutron star into a giant permanent magnet, something Hansson and Ponga call a “neutromagnet”.

Similar to its smaller permanent magnet cousins, a neutromagnet would be extremely stable. The magnetic field of a neutromagnet is thought to align with the original magnetic field of the “parent” star, which appears to act as a catalyst. What is even more interesting is that the original magnetic field isn’t required to be in the same direction as the spin axis.

One more interesting fact is that with all neutron stars having nearly the same mass, Hansson and Ponga can calculate the strength of the magnetic fields the neutromagnets should generate. Based on their calculations, the strength is about 1012 Tesla’s – almost exactly the observed value detected around the most intense magnetic fields around neutron stars. The team’s calculations appear to solve several unsolved problems regarding pulsars.

Hansson and Ponga’s theory is simple to test – since they state the magnetic field strength of neutron stars cannot exceed 1012 Tesla’s. If a neutron star were to be discovered with a stronger magnetic field than 1012 Tesla’s, the team’s theory would be proven wrong.

Due to the Pauli exclusion principle possibly excluding neutrons aligning in the manner outlined in Hansson and Ponga’s paper, there are some questions regarding the team’s theory. Hansson and Ponga point to experiments that have been performed which suggest that nuclear spins can become ordered, like ferromagnets, stating: “One should remember that the nuclear physics at these extreme circumstances and densities is not known a priori, so several unexpected properties might apply,”

While Hansson and Ponga readily agree their theories are purely speculative, they feel their theory is worth pursuing in more detail.

If you’d like to learn more, you can read the full scientific paper by Hansson & Pong at: http://arxiv.org/pdf/1111.3434v1

Source: Pulsars: Cosmic Permanent ‘Neutromagnets’ (Hansson & Pong)

Posted on by Tammy Plotner

The Way Cool Clouds Of The Carina Nebula

The APEX observations, made with its LABOCA camera, are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory. The result is a dramatic, wide-field picture that provides a spectacular view of Carina’s star formation sites. The nebula contains stars equivalent to over 25 000 Suns, and the total mass of gas and dust clouds is that of about 140 000 Suns.

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It’s beautiful…. But it’s cold. By utilizing the submillimetre-wavelength of light, the 12 meter APEX telescope has imaged the frigid, dusty clouds of star formation in the Carina Nebula. Here, some 7500 light-years away, unrestrained stellar creation produces some of the most massive stars known to our galaxy… a picturesque petri dish in which we can monitor the interaction between the neophyte suns and their spawning molecular clouds.

By examining the region in submillimetre light through the eyes of the LABOCA camera on the Atacama Pathfinder Experiment (APEX) telescope on the plateau of Chajnantor in the Chilean Andes, a team of astronomers led by Thomas Preibisch (Universitäts–Sternwarte München, Ludwig-Maximilians-Universität, Germany), in close cooperation with Karl Menten and Frederic Schuller (Max-Planck-Institut für Radioastronomie, Bonn, Germany), have been able to pick apart the faint heat signature of cosmic dust grains. These tiny particles are cold – about minus 250 degrees C – and can only be detected at these extreme, long wavelengths. The APEX LABOCA observations are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory.

This amalgamate image reveals the Carina nebula in all its glory. Here we see stars with mass exceeding 25,000 sun-like stars embedded in dust clouds with six times more mass. The yellow star in the upper left of the image – Eta Carinae – is 100 times the mass of the Sun and the most luminous star known. It is estimated that within the next million years or so, it will go supernova, taking its neighbors with it. But for all the tension in this region, only a small part of the gas in the Carina Nebula is dense enough to trigger more star formation. What’s the cause? The reason may be the massive stars themselves…

With an average life expectancy of just a few million years, high-mass stars have a huge impact on their environment. While initially forming, their intense stellar winds and radiation sculpt the gaseous regions surrounding them and may sufficiently compress the gas enough to trigger star birth. As their time closes, they become unstable – shedding off material until the time of supernova. When this intense release of energy impacts the molecular gas clouds, it will tear them apart at short range, but may trigger star-formation at the periphery – where the shock wave has a lesser impact. The supernovae could also spawn short-lived radioactive atoms which could become incorporated into the collapsing clouds that could eventually produce a planet-forming solar nebula.

Then things will really heat up!

Original Story Source: ESO News Release.

Posted on by Tammy Plotner

Do Galaxies Recycle Their Material?

Distant quasars shine through the gas-rich "fog" of hot plasma encircling galaxies. At ultraviolet wavelengths, Hubble's Cosmic Origins Spectrograph (COS) is sensitive to absorption from many ionized heavy elements, such as nitrogen, oxygen, and neon. COS's high sensitivity allows many galaxies that happen to lie in front of the much more distant quasars. The ionized heavy elements serve as proxies for estimating how much mass is in a galaxy's halo. (Credit: NASA; ESA; A. Feild, STScI)

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It’s a great question that’s now been validated by the Hubble Space Telescope. Recent observations have shown how galaxies are able to recycle huge amounts of hydrogen gas and heavy elements within themselves. In a process which begins at initial star formation and lasts for billions of years, galaxies renew their own energy sources.

Thanks to the HST’s Cosmic Origins Spectrograph (COS), scientists have now been able to investigate the Milky Way’s halo region along with forty other galaxies. The combined data includes instruments from large ground-based telescopes in Hawaii, Arizona and Chile whose goal was determine galaxy properties. In this colorful instance, the shape and spectra of each individual galaxy would appear to be influenced by gas flow through the halo in a type of “gas-recycling phenomenon”. The results are being published in three papers in the November 18 issue of Science magazine. The leaders of the three studies are Nicolas Lehner of the University of Notre Dame in South Bend, Ind.; Jason Tumlinson of the Space Telescope Science Institute in Baltimore, Md.; and Todd Tripp of the University of Massachusetts at Amherst.

The focus of the research centered on distant stars whose spectra illuminated influxing gas clouds as they pass through the galactic halo. This is the basis of continual star formation, where huge pockets of hydrogen contain enough fuel to ignite a hundred million stars. But not all of this gas is just “there”. A substantial portion is recycled by both novae and supernovae events – as well as star formation itself. It not only creates, but “replenishes”.

The color and shape of a galaxy is largely controlled by gas flowing through an extended halo around it. All modern simulations of galaxy formation find that they cannot explain the observed properties of galaxies without modeling the complex accretion and "feedback" processes by which galaxies acquire gas and then later expel it after chemical processing by stars. Hubble spectroscopic observations show that galaxies like our Milky Way recycle gas while galaxies undergoing a rapid starburst of activity will lose gas into intergalactic space and become "red and dead." (Credit: NASA; ESA; A. Feild, STScI)

However, this process isn’t unique to the Milky Way. Hubble’s COS observations have recorded these recycling halos around energetic star-forming galaxies, too. These heavy metal halos are reaching out to distances of up to 450,000 light years outside the visible portions of their galactic disks. To capture such far-reaching evidence of galactic recycling wasn’t an expected result. According to the Hubble Press Release, COS measured 10 million solar masses of oxygen in a galaxy’s halo, which corresponds to about one billion solar masses of gas – as much as in the entire space between stars in a galaxy’s disk.

So what did the research find and how was it done? In galaxies with rapid star formation, the gases are expelled outward at speed of up to two million miles per hour – fast enough to be ejected to the point of no return – and with it goes mass. This confirms the theories of how a spiral galaxy could eventually evolve into an elliptical. Since the light from this hot plasma isn’t within the visible spectrum, the COS used quasars to reveal the spectral properties of the halo gases. Its extremely sensitive equipment was able to detect the presence of heavy elements, such as nitrogen, oxygen, and neon – indicators of mass of a galaxy’s halo.

So what happens when a galaxy isn’t “green”? According to these new observations, galaxies which have ceased star formation no longer have gas. Apparently, once the recycling process stops, stars will only continue to form for as long as they have fuel. And once it’s gone?

It’s gone forever…

Original Story Source: Hubble Space Telescope News Release.

Posted on by Tammy Plotner

Antique Stars Could Help Solve Mysteries Of Early Milky Way

The Milky Way is like NGC 4594 (pictured), a disc shaped spiral galaxy with around 200 billion stars. The three main features are the central bulge, the disk, and the halo. Credit: ESO
The Milky Way is like NGC 4594 (pictured), a disc shaped spiral galaxy with around 200 billion stars. The three main features are the central bulge, the disk, and the halo. Credit: ESO

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Utilizing ESO’s giant telescopes located in Chile, researchers at the Niels Bohr Institute have been examining “antique” stars. Located at the outer reaches of the Milky Way, these superannuated stellar specimens are unusual in the fact that they contain an over-abundance of gold, platinum and uranium. How they became heavy metal stars has always been a puzzle, but now astronomers are tracing their origins back to our galaxy’s beginning.

It is theorized that soon after the Big Bang event, the Universe was filled with hydrogen, helium and… dark matter. When the trio began compressing upon themselves, the very first stars were born. At the core of these neophyte suns, heavy elements such as carbon, nitrogen and oxygen were then created. A few hundred million years later? Hey! All of the elements are now accounted for. It’s a tidy solution, but there’s just one problem. It would appear the very first stars only had about 1/1000th of the heavy-elements found in sun-like stars of the present.

How does it happen? Each time a massive star reaches the end of its lifetime, it will either create a planetary nebula – where layers of elements gradually peel away from the core – or it will go supernova – and blast the freshly created elements out in a violent explosion. In this scenario, the clouds of material once again coalesce… collapse again and form more new stars. It’s just this pattern which gives birth to stars that become more and more “elementally” concentrated. It’s an accepted conjecture – and that’s what makes discovering heavy metal stars in the early Universe a surprise. And even more surprising…

Right here in the Milky Way.

“In the outer parts of the Milky Way there are old ‘stellar fossils’ from our own galaxy’s childhood. These old stars lie in a halo above and below the galaxy’s flat disc. In a small percentage – approximately one to two percent of these primitive stars, you find abnormal quantities of the heaviest elements relative to iron and other ‘normal’ heavy elements”, explains Terese Hansen, who is an astrophysicist in the research group Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen.

The 17 observed stars are all located in the northern sky and could therefore be observed with the Nordic Optical Telescope, NOT on La Palma. NOT is 2.5 meter telescope that is well suited for just this kind of observations, where continuous precise observations of stellar motions over several years can reveal what stars belong to binary star systems.
But the study of these antique stars just didn’t happen overnight. By employing ESO’s large telescopes based in Chile, the team took several years to come to their conclusions. It was based on the findings of 17 “abnormal” stars which appeared to have elemental concentrations – and then another four years of study using the Nordic Optical Telescope on La Palma. Terese Hansen used her master’s thesis to analyse the observations.

“After slaving away on these very difficult observations for a few years I suddenly realised that three of the stars had clear orbital motions that we could define, while the rest didn’t budge out of place and this was an important clue to explaining what kind of mechanism must have created the elements in the stars”, explains Terese Hansen, who calculated the velocities along with researchers from the Niels Bohr Institute and Michigan State University, USA.

What exactly accounts for these types of concentrations? Hansen explains their are two popular theories. The first places the origin as a close binary star system where one goes supernova, inundating its companion with layers of heavier elements. The second is a massive star also goes supernova, but spews the elements out in dispersing streams, impregnating gas clouds which then formed into the halo stars.

The research group has analysed 17 stellar fossils from the Milky Way’s childhood. The stars are small light stars and they live longer than large massive stars. They do not burn hydrogen longer, but swell up into red giants that will later cool and become white dwarves. The image shows the most famous of the stars CS31082-001, which was the first star that uranium was found in.
“My observations of the motions of the stars showed that the great majority of the 17 heavy-element rich stars are in fact single. Only three (20 percent) belong to binary star systems – this is completely normal, 20 percent of all stars belong to binary star systems. So the theory of the gold-plated neighbouring star cannot be the general explanation. The reason why some of the old stars became abnormally rich in heavy elements must therefore be that exploding supernovae sent jets out into space. 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”, says Terese Hansen, who immediately after her groundbreaking results was offered a PhD grant by one of the leading European research groups in astrophysics at the University of Heidelberg.

May all heavy metal stars go gold!

Original Story Source: Niels Bohr Institute News Release. For Further Reading: The Binary Frequency of r-Process-element-enhanced Metal-poor Stars and Its Implications: Chemical Tagging in the Primitive Halo of the Milky Way.

Posted on by Tammy Plotner

New NASA Mission Hunts Down Zombie Stars

This is an artist's concept of a pulsar (blue-white disk in center) pulling in matter from a nearby star (red disk at upper right). The stellar material forms a disk around the pulsar (multicolored ring) before falling on to the surface at the magnetic poles. The pulsar's intense magnetic field is represented by faint blue outlines surrounding the pulsar. Credit: NASA

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Neutron stars have been classed as “undead”… real zombie stars. Even though technically defunct, the neutron star continues to shine – and occasionally feed on a neighbor if it gets too close. They are born when a massive star collapses under its gravity and its outer layers are blown far and wide, outshining a billion suns, in a supernova event. What’s left is a stellar corpse… a core of inconceivable density… where one teaspoon would weigh about a billion tons on Earth. How would we study such a curiosity? NASA has proposed a mission called the Neutron Star Interior Composition Explorer (NICER) that would detect the zombie and allow us to see into the dark heart of a neutron star.

The core of a neutron star is pretty incredible. Despite the fact that it has blown away most of its exterior and stopped nuclear fusion, it still radiates heat from the explosion and exudes a magnetic field which tips the scales. This intense form of radiation caused by core collapse measures out at over a trillion times stronger than Earth’s magnetic field. If you don’t think that impressive, then think of the size. Originally the star could have been a trillion miles or more in diameter, yet now is compressed to the size of an average city. That makes a neutron star a tiny dynamo – capable of condensing matter into itself at more than 1.4 times the content of the Sun, or at least 460,000 Earths.

“A neutron star is right at the threshold of matter as it can exist – if it gets any denser, it becomes a black hole,” says Dr. Zaven Arzoumanian of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We have no way of creating neutron star interiors on Earth, so what happens to matter under such incredible pressure is a mystery – there are many theories about how it behaves. The closest we come to simulating these conditions is in particle accelerators that smash atoms together at almost the speed of light. However, these collisions are not an exact substitute – they only last a split second, and they generate temperatures that are much higher than what’s inside neutron stars.”

If approved, the NICER mission will be launched by the summer of 2016 and attached robotically to the International Space Station. In September 2011, NASA selected NICER for study as a potential Explorer Mission of Opportunity. The mission will receive $250,000 to conduct an 11-month implementation concept study. Five Mission of Opportunity proposals were selected from 20 submissions. Following the detailed studies, NASA plans to select for development one or more of the five Mission of Opportunity proposals in February 2013.

This is an artist's concept of the NICER instrument on board the International Space Station. NICER is the cube in the foreground on the left. The circular objects protruding from the cube are telescopes that focus X-rays from the pulsar on to the detector. Credit: NASA

What will NICER do? First off, an array of 56 telescopes will gather X-ray information from a neutron stars magnetic poles and hotspots. It is from these areas that our zombie stars release X-rays, and as they rotate create a pulse of light – thereby the term “pulsar”. As the neutron star shrinks, it spins faster and the resultant intense gravity can pull in material from a closely orbiting star. Some of these pulsars spin so fast they can reach speeds of several hundred of rotations per second! What scientists are itching to understand is how matter behaves inside a neutron star and “pinning down the correct Equation Of State (EOS) that most accurately describes how matter responds to increasing pressure. Currently, there are many suggested EOSs, each proposing that matter can be compressed by different amounts inside neutron stars. Suppose you held two balls of the same size, but one was made of foam and the other was made of wood. You could squeeze the foam ball down to a smaller size than the wooden one. In the same way, an EOS that says matter is highly compressible will predict a smaller neutron star for a given mass than an EOS that says matter is less compressible.”

Now all NICER will need to do is help us to measure a pulsar’s mass. Once it is determined, we can get a correct EOS and unlock the mystery of how matter behaves under intense gravity. “The problem is that neutron stars are small, and much too far away to allow their sizes to be measured directly,” says NICER Principal Investigator Dr. Keith Gendreau of NASA Goddard. “However, NICER will be the first mission that has enough sensitivity and time-resolution to figure out a neutron star’s size indirectly. The key is to precisely measure how much the brightness of the X-rays changes as the neutron star rotates.”

So what else does our zombie star do that’s impressive? Because of their extreme gravity in such small volume, they distort space/time in accordance with Einstein’s theory of General Relativity. It is this space “warp” that allows astronomers to reveal the presence of a companion star. It also produces effects like an orbital shift called precession, allowing the pair to orbit around each other causing gravitational waves and producing measurable orbital energy. One of the goals of NICER is to detect these effects. The warp itself will allow the team to determine the neutron star’s size. How? Imagine pushing your finger into a stretchy material – then imagine pushing your whole hand against it. The smaller the neutron star, the more it will warp space and light.

Here light curves become very important. When a neutron star’s hotspots are aligned with our observations, the brightness increases as one rotates into view and dims as it rotates away. This results in a light curve with large waves. But, when space is distorted we’re allowed to view around the curve and see the second hotspot – resulting in a light curve with smoother, smaller waves. The team has models that produce “unique light curves for the various sizes predicted by different EOSs. By choosing the light curve that best matches the observed one, they will get the correct EOS and solve the riddle of matter on the edge of oblivion.”

And breathe life into zombie stars…

Original Story Source: NASA Mission News.

Posted on by Tammy Plotner

Early Galaxy Chemistry: VLT Observes Gamma-Ray Burst

Artist’s impression of a gamma-ray burst shining through two young galaxies in the early Universe. Credit: ESO

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“Shot through the heart and you’re to blame…” There’s nothing more powerful than a gamma-ray burst. These abrupt, mega-bright events are captured by orbiting telescopes where the information is immediately relayed to the ground for observation in visible light and infra-red. Some events are so powerful that they linger for hours or even days. But just how quick can we spot them? A burst cataloged as GRB 090323 was picked up by the NASA Fermi Gamma-ray Space Telescope, then confirmed by the X-ray detector on NASA’s Swift satellite and with the GROND system at the MPG/ESO 2.2-metre telescope in Chile. Within a day it was being studied by ESO’s Very Large Telescope. It was so intense it penetrated its host galaxy and another… heading out on a 12 billion light year journey just to get here.

“When we studied the light from this gamma-ray burst we didn’t know what we might find. It was a surprise that the cool gas in these two galaxies in the early Universe proved to have such an unexpected chemical make-up,” explains Sandra Savaglio (Max-Planck Institute for Extraterrestrial Physics, Garching, Germany), lead author of the paper describing the new results. “These galaxies have more heavy elements than have ever been seen in a galaxy so early in the evolution of the Universe. We didn’t expect the Universe to be so mature, so chemically evolved, so early on.”

As the brilliant beacon passed through the galaxies, the gases performed as a filter, absorbing some wavelengths of light. But the real kicker here is we wouldn’t have even known these galaxies existed if it weren’t for the gamma-ray burst! Because the light was affected, astronomers were able to detect the “composition of the cool gas in these very distant galaxies, and in particular how rich they were in heavy elements.” It had been surmised that early galaxies would have less heavy elements since their stellar populations weren’t old enough to have produced them… But the findings pointed otherwise. These new galaxies were rich in heavy elements and going against what we thought we knew about galactic evolution.

So exactly what does that mean? It would appear these new, young galaxies are forming stars at an incredible rate. To enrich their gases so quickly, it’s possible they are in a merger process. While this isn’t a new concept, it just may support the theory that gamma-ray bursts can be associated with “vigorous massive star formation”. Furthermore, it’s surmised that rapid stellar growth may have simply stopped in the primordial Universe. What’s left that we can observe some 12 billion years later are mere shadows of what once was… like cool dwarf stars and black holes. These two newly discovered galaxies are like finding a hidden stain on the outskirts of the distant Cosmos.

“We were very lucky to observe GRB 090323 when it was still sufficiently bright, so that it was possible to obtain spectacularly detailed observations with the VLT. Gamma-ray bursts only stay bright for a very short time and getting good quality data is very hard. We hope to observe these galaxies again in the future when we have much more sensitive instruments, they would make perfect targets for the E-ELT,” concludes Savaglio.

Original Story Source: ESO Press Release. For Further Reading: Super-solar Metal Abundances in Two Galaxies at z ~ 3.57 revealed by the GRB 090323 Afterglow Spectrum.

Posted on by Paul Scott Anderson

Three New Planets and a Mystery Object Found Orbiting Dying Stars

A planet about to be consumed by its expanding red giant star. Credit: Mark Garlik/HELAS

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Some interesting new additions to the exoplanet family were announced last week by astronomers from Penn State University. While finding exoplanets these days may be considered “just another day at the office,” astronomers discovered three unique planets and an additional “mystery” object. What’s unique about these planets is the fact that the stars they orbit are all old and dying – red giant stars which have swollen up as they near the end of their lives, which ordinarily would consume any unlucky planets which may be too close to escape…

The three stars are HD 240237, BD +48 738, and HD 96127; the second one also has the mystery object orbiting it, which may be another planet, a low-mass star or a brown dwarf — something whose mass is in between that of a smaller, cooler star and a giant planet.

“We will continue to watch this strange object and, in a few more years, we hope to be able to reveal its identity,” said team leader, Alex Wolszczan.

Wolszczan was the first astronomer to discover exoplanets, three small planets orbiting a pulsar (neutron star) in 1992.

It is expected that our own Sun will also become a red giant star in another five billion years or so. Not a good thing for us obviously, but still a long ways off thankfully, since at that time, all of the inner planets of the solar system will probably be consumed by the expanding Sun.

The subject of planets orbiting dying stars will also be the focus of an upcoming conference, Planets Around Stellar Remnants, in Puerto Rico next January. It is organized by Penn State’s Center for Exoplanets and Habitable Worlds, and will take place exactly 20 years since Wolszczan made his discovery.

Interesting, since by far most of the exoplanets found so far orbit “normal” stars, like our Sun, which are still in mid-life or younger. But now, they’ve been observed around stars at all different stages of evolution, from the youngest stars, even those still with protoplanetary disks, to the oldest, stars which have already died and burned out, like pulsars. What this seems to indicate is that planets are a normal part of star formation, from beginning to end. The numbers now being found by astronomers, in the thousands and likely millions or billions, also suggest this; a big change from just a few decades ago when it was unknown if there were any other solar systems out there at all. There are, a lot of them.

Source: Penn State University

Posted on by Nancy Atkinson

Guest Post by Author Peter Shaver: Cosmic Time Scales

This single all-sky image, captured by the Planck telescope, simultaneously captured two snapshots that straddle virtually the entire 13.7 billion year history of the universe. Credit: ESA

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Editor’s note: Peter Shaver is the author of the new book “Cosmic Heritage – Evolution from the Big Bang to Conscious Life.” Find out here how you can win a copy!

The universe has gone through a number of distinct phases. The first part of the first second is speculative, but the physics of the latter part is well know to us. In the first several minutes the lightest elements (hydrogen and helium) were formed.

Over the next 380,000 years the universe was a hot (but always cooling) plasma of electrons, nuclei and photons. At 380,000 years it was cool enough for electrons and nuclei to combine into atoms, in a process called recombination. The photons were freed from the plasma, and the universe became transparent for the first time. As the universe was opaque before recombination and transparent after, we see this epoch as a ‘wall’, and it is known as the cosmic microwave background.

What followed was a period known as the ‘cosmic dark ages’. The only light was that of the fading afterglow of the Big Bang, and the matter was comprised of the primordial elements and the exotic ‘dark matter’. During this time gravitational accretion slowly but surely produced larger and larger concentrations of matter, and when these became sufficiently dense, nuclear reactions could form and the first stars and galaxies were born. These lit up and ionized the universe again, some 400-500 million years after the Big Bang, in what is known as the ‘reionization epoch’.

The activity increased exponentially, culminating in the ‘quasar epoch’ 2-4 billion years after the Big Bang, a frenetic period of chaotic star and galaxy formation, galaxy interactions, monster quasars and radio galaxies. This activity eventually began to drop off, although it still continues today; the incidence of quasars today is a thousand times less than it was at the peak of the quasar epoch. At 13.7 billion years, the universe has now reached a ‘dignified middle age’.

The ‘heavy elements’ such as carbon and oxygen, essential for life as we know it, are all produced in stars, and this process has been going on ever since the first stars formed. Each generation of stars ejects more heavy elements into the intergalactic medium, so the abundances of the heavy elements have been built up over time.

By the time the Sun and Earth were formed 4.6 billion years ago, over 8.4 billion years of star and planet formation had already taken place in the universe. Star formation still takes place today, so in total there have been over 13 billion years of star and planet formation.

Zooming in now to our planet, life started not long after the Earth itself formed, sometime between 3.8 and 3.5 billion years ago (bya). But for almost half the age of the Earth, the only forms of life were microorganisms such as bacteria. More complex life forms started to appear about 1-2 bya. Invertebrates, which appeared some 600 million years ago (mya), were the earliest multicellular life forms, and vertebrates appeared about 500 mya. Life invaded the land about 400 mya. The dinosaurs dominated from 240 mya until their extinction 66 mya, and then mammals gradually took over. Many species came and went. Our closest living relatives are the chimpanzees, which split off from our ancestral line 5-6 mya; our more recent relatives have all become extinct.

It is amazing to think how recently humans appeared on the cosmic scene. Our species only appeared about 200,000 years ago, our ancestors emerged out of Africa just 50,000 years ago, agriculture started 10,000 years ago, and we have had modern technology for only the last 100 years or so! We are newcomers to the universe.

We now know that there are planets orbiting other stars like our Sun, probably billions of them in our galaxy alone, and billions more in the billions of other galaxies. Given the huge timescale of the universe, any life on those planets is bound to be millions or billions of years more or less advanced than life on Earth. If it is less advanced, it would certainly not be able to communicate with us. If it is more advanced, its technology would probably be totally unrecognisable to us. Nevertheless, we are probably not alone in the universe.

Of course the timescales discussed above only cover the ‘conventional’ universe from the Big Bang to now. If there was a ‘preexisting’ multiverse, we have no idea how far back any ‘before’ may extend. And as the expansion of the universe is accelerating, the future of the universe may be very long indeed: trillions upon trillions of years.

Peter Shaver obtained a PhD in astrophysics at the University of Sydney in Australia, and spent most of his career as a senior scientist at the European Southern Observatory (ESO), based in Munich. He has authored or co-authored over 250 scientific papers, and edited six books on astronomy and astrophysics.

Posted on by Tammy Plotner

Free Range Brown Dwarfs

Brown dwarfs in the young star cluster NGC 1333. This photograph combines optical and infrared images taken with the Subaru Telescope. Brown dwarfs newly identified by the SONYC Survey are circled in yellow, while previously known brown dwarfs are circled in white. The arrow points to the least massive brown dwarf known in NGC 1333; it is only about six times heftier than Jupiter. Credit: SONYC Team/Subaru Telescope

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Using two of the world’s largest optical-infrared telescopes, the Subaru Telescope in Hawaii and the Very Large Telescope (VLT) in Chile, an international team of astronomers has discovered more than two dozen brown dwarf stars floating around in two galactic clusters. During the Substellar Objects in Nearby Young Clusters (SONYC) survey, these “failed stars” came to their attention by showing up in extremely deep images of the NGC 1333 and rho Ophiuchi star clusters at both optical and infrared wavelengths. To make the findings even more exciting, these stellar curiosities outnumbered the “normal” stars in one cluster!

“Our findings suggest once again that objects not much bigger than Jupiter could form the same way as stars do. In other words, nature appears to have more than one trick up its sleeve for producing planetary mass objects,” says Professor Ray Jayawardhana, Canada Research Chair in Observational Astrophysics at the University of Toronto and leader of the international team. Their discovery will be published in two upcoming papers in the Astrophysical Journal and will be presented this week at a scientific conference in Garching, Germany.

Spectra of several brown dwarfs in the young star cluster NGC1333, taken with the FMOS instrument on the Subaru Telescope. The spectra show a characteristic peak around 1670nm. Water steam in a brown dwarf's atmosphere absorbs radiation on both sides of the peak. The plot shows that the strength of the water absorption increases in cooler objects (from 3000 to 2200K). FMOS allows astronomers to take spectra for many objects simultaneously, a crucial advantage for the SONYC Survey. Credit: SONYC Team/Subaru Telescope

Using spectroscopy, the researchers were able to separate candidate brown dwarfs by their red color. But there’s more to the story than just hues. In this case, it’s the identification of one that’s only about six times more massive than Jupiter. Located in NGC 1333, it is the smallest known free-floating object to date. What does that mean? “Its mass is comparable to those of giant planets, yet it doesn’t circle a star. How it formed is a mystery,” said Aleks Scholz of the Dublin Institute for Advanced Studies in Ireland, lead author of the first paper.

Brown dwarfs are indeed unusual. They walk a fine line between planet and star – and may have once been in stellar orbit, only to be ejected at some point in time. But in this circumstance, all of the brown dwarfs found in this particular cluster have very low mass – only about twenty times that of Jupiter. “Brown dwarfs seem to be more common in NGC 1333 than in other young star clusters. That difference may be hinting at how different environmental conditions affect their formation,” said Koraljka Muzic of the University of Toronto in Canada, lead author of the second paper.

“We could not have made these exciting discoveries if not for the remarkable capabilities of Subaru and the VLT. Instruments that can image large patches of the sky and take hundreds of spectra at once are key to our success,” said Motohide Tamura of the National Astronomical Observatory of Japan.

Free-range brown dwarfs? I’ll take mine over easy…

Original Story Source: Subaru Telescope News.