Posted on by Nancy Atkinson

Starbursts May Actually Destroy Globular Clusters

The Galactic globular cluster M80 in the constellation Scorpius contains several hundred thousand stars. Credit: HST/NASA/ESA

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It seems logical to assume that long ago, the amount of globular clusters increased in our galaxy during star-making frenzies called ‘starbursts.’ But a new computer simulation shows just the opposite: 13 billion years ago, starbursts may have actually destroyed many of the globular clusters that they helped to create.

“It is ironic to see that starbursts may produce many young stellar clusters, but at the same time also destroy the majority of them,” said Dr. Diederik Kruijssen of the Max Planck Institute for Astrophysics. “This occurs not only in galaxy collisions, but should be expected in any starburst environment”

Astronomers have wondered why throughout the Universe, typical globular star clusters contain about the same number of stars. In contrast much younger stellar clusters can contain almost any number of stars, from fewer than 100 to many thousands.

The new computer simulation by Kruijssen and his team proposes that this difference could be explained by the conditions under which globular clusters formed early on in the evolution of their host galaxies.

In the early Universe, starbursts were common. Large galaxies were in clusters, and collisions occurred often. The computer simulation showed that during starbursts, gas, dust and stars were still being sloshed around from the galaxy collision, with the pull of gravity on the globular clusters constantly changing. This was enough to rip apart most of the globular clusters and only the biggest ones were strong enough to survive. The simulations showed most of the star clusters were destroyed shortly after their formation, when the galactic environment was still very hostile to the young clusters. But after the environment calmed down, the surviving globular clusters have survived – now living quietly – and we can still enjoy their beauty.

In their paper, the astronomers say that this explains why the number of stars contained within globular clusters is roughly the same across the entire Universe. “It therefore makes perfect sense that all globular clusters have approximately the same large number of stars,” said Kruijssen. “Their smaller brothers and sisters that didn’t contain as many stars were doomed to be destroyed.”

Kruijssen and his team said that while the very brightest and largest clusters were capable of surviving the galaxy collision due to their own gravitational attraction, numerous smaller clusters were effectively destroyed by the rapidly changing gravitational forces.

The fact that globular clusters are comparable everywhere then indicates that the environments in which they formed were very similar, regardless of the galaxy they currently reside in. Kruijssen and his team says globular clusters can therefore be used to shed more light on how the first generations of stars and galaxies were born.

“In the nearby Universe, there are several examples of galaxies that have recently undergone large bursts of star formation,” said Kruijssen. “It should therefore be possible to see the rapid destruction of small stellar clusters in action. If this is indeed found by new observations, it will confirm our theory for the origin of globular clusters.”

This new finding may also tie in with other recent findings from Spitzer and ESO that starburst activity may have only lasted around 100 million years and may have also been cut short when black holes formed at the center of galaxies.

Source: Max-Planck Institute for Astrophysics. Paper: Kruijssen et al, “Formation versus destruction: the evolution of the star cluster population in galaxy mergers”

Posted on by Tammy Plotner

Emerging Supermassive Black Holes Choke Star Formation

The LABOCA camera on the ESO-operated 12-metre Atacama Pathfinder Experiment (APEX) telescope reveals distant galaxies undergoing the most intense type of star formation activity known, called a starburst. This image shows these distant galaxies, found in a region of sky known as the Extended Chandra Deep Field South, in the constellation of Fornax (The Furnace). The galaxies seen by LABOCA are shown in red, overlaid on an infrared view of the region as seen by the IRAC camera on the Spitzer Space Telescope. Credit: ESO, APEX (MPIfR/ESO/OSO), A. Weiss et al., NASA Spitzer Science Center

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Located on the Chajnantor plateau in the foothills of the Chilean Andes, ESO’s APEX telescope has been busy looking into deep, deep space. Recently a group of astronomers released their findings regarding massive galaxies in connection with extreme times of star formation in the early Universe. What they found was a sharp cut-off point in stellar creation, leaving “massive – but passive – galaxies” filled with mature stars. What could cause such a scenario? Try the materialization of a supermassive black hole…

By integrating data taken with the LABOCA camera on the ESO-operated 12-metre Atacama Pathfinder Experiment (APEX) telescope with measurements made with ESO’s Very Large Telescope, NASA’s Spitzer Space Telescope and other facilities, astronomers were able to observe the relationship of bright, distant galaxies where they form into clusters. They found that the density of the population plays a major role – the tighter the grouping, the more massive the dark matter halo. These findings are the considered the most accurate made so far for this galaxy type.

Located about 10 billion light years away, these submillimetre galaxies were once home to starburst events – a time of intense formation. By obtaining estimations of dark matter halos and combining that information with computer modeling, scientists are able to hypothesize how the halos expanding with time. Eventually these once active galaxies settled down to form giant ellipticals – the most massive type known.

“This is the first time that we’ve been able to show this clear link between the most energetic starbursting galaxies in the early Universe, and the most massive galaxies in the present day,” says team leader Ryan Hickox of Dartmouth College, USA and Durham University, UK.

However, that’s not all the new observations have uncovered. Right now there’s speculation the starburst activity may have only lasted around 100 million years. While this is a very short period of cosmological time, this massive galactic function was once capable of producing double the amount of stars. Why it should end so suddenly is a puzzle that astronomers are eager to understand.

“We know that massive elliptical galaxies stopped producing stars rather suddenly a long time ago, and are now passive. And scientists are wondering what could possibly be powerful enough to shut down an entire galaxy’s starburst,” says team member Julie Wardlow of the University of California at Irvine, USA and Durham University, UK.

Right now the team’s findings are offering up a new solution. Perhaps at one point in cosmic history, starburst galaxies may have clustered together similar to quasars… locating themselves in the same dark matter halos. As one of the most kinetic forces in our Universe, quasars release intense radiation which is reasoned to be fostered by central black holes. This new evidence suggests intense starburst activity also empowers the quasar by supplying copious amounts of material to the black hole. In response, the quasar then releases a surge of energy which could eradicate the galaxy’s leftover gases. Without this elemental fuel, stars can no longer form and the galaxy growth comes to a halt.

“In short, the galaxies’ glory days of intense star formation also doom them by feeding the giant black hole at their centre, which then rapidly blows away or destroys the star-forming clouds,” explains team member David Alexander from Durham University, UK.

Original Story Source: European Southern Observatory News. For Further Reading: Research Paper Link.

Posted on by Paul Scott Anderson

Citizen Scientist Project Finds Thousands of ‘Star Bubbles’

A prominent star bubble. Credit: NASA / The Milky Way Project / Zooniverse

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Remember when you were a kid and blowing bubbles was such great fun? Well, stars kind of do that too. The “bubbles” are partial or complete rings of dust and gas that occur around young stars in active star-forming regions, known as stellar nurseries. So far, over 5,000 bubbles have been found, but there are many more out there awaiting discovery. Now there is a project that you can take part in yourself, to help find more of these intriguing objects.

The Milky Way Project, part of Zooniverse, has been cataloguing these cosmic bubbles thanks to assistance from the public, or “citizen scientists” – anyone can help by examining images from the Spitzer Space Telescope, specifically the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) and the Multiband Imaging Photometer for Spitzer Galactic Plane Survey (MIPSGAL).

They have been seen before, but now the task is to find as many as possible in the newer, high-resolution images from Spitzer. A previous catalogue of star bubbles in 2007 listed 269 of them. Four other researchers had found about 600 of them in 2006. Now they are being found by the thousands. As of now, the new catalogue lists 5,106 bubbles, after looking at almost half a million images so far. As it turns out, humans are more skilled at identifying them in the images than a computer algorithm would be. People are better at pattern recognition and then making a judgment based on the data as to what actually is a bubble and what isn’t.

The bubbles form around hot, young massive stars where it is thought that the intense light being emitted causes a shock wave, blowing out a space, or bubble, in the surrounding gas and dust.

Eli Bressert, of the European Southern Observatory and Milky Way Project team member, stated that our galaxy “is basically like champagne, there are so many bubbles.” He adds, “We thought we were going to be able to answer a lot of questions, but it’s going to be bringing us way more questions than answers right now. This is really starting something new in astronomy that we haven’t been able to do.”

There are currently about 35,000 volunteers in the project; if you would like to take part, you can go to The Milky Way Project for more information.

Posted on by Jon Voisey

“Proplyd-like” Objects Discovered in Cygnus OB2

Hubble image of a Proplyd-like object in Cygnus OB2. Credit: Z. Levay and L. Frattare, STScI
Hubble image of a Proplyd-like object in Cygnus OB2. Credit: Z. Levay and L. Frattare, STScI

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The well known Orion Nebula is perhaps the most well known star forming regions in the sky. The four massive stars known as the trapezium illuminate the massive cloud of gas and dust busily forming into new stars providing astronomers a stunning vista to explore stellar formation and young systems. In the region are numerous “protoplanetary disks” or proplyds for short which are regions of dense gas around a newly formed star. Such disks are common around young stars and have recently been discovered in an even more massive, but less well known star forming region within our own galaxy: Cygnus OB2.

Ten times more massive than its more famous counterpart in Orion, Cygnus OB2 is a star forming region that is a portion of a larger collection of gas known as Cygnus X. The OB2 region is notable because, like the Orion nebula, it contains several exceptionally massive stars including OB2-12 which is one of the most massive and luminous stars within our own galaxy. In total the region has more than 65 O class stars, the most massive category in astronomers classification system. Yet for as bright as these stars are, Cygnus OB2 is not a popular target for amateur astronomers due to its position behind a dark obscuring cloud which blocks the majority of visible light.

But like many objects obscured in this manner, infrared and radio telescopes have been used to pierce the veil and study the region. The new study, led by Nicholas Wright at the Harvard-Smithsonian Center for Astrophysics, combines infrared and visual observations from the Hubble Space telescope. The observations revealed 10 objects similar in appearance to the Orion proplyds. The objects had long tails being blown away from the central mass due to the strong stellar winds from the central cluster similar to how proplyds in Orion point away from the trapezium. On the closer end, the objects were brightly ionized.

Yet despite the similarities, the objects may not be true proplyds. Instead, they may be regions known as “evaporating gaseous globules” or EGGs for short. The key difference between the two is whether or not a star has formed. EGGs are overdense regions within a larger nebula. Their size and density makes them resistant to the ionization and stripping that blows away the rest of the nebula. Because the interior regions are shielded from these dispersive forces, the center may collapse to form a star which is the requirement for a proplyd. So which are these?

In general, the newly discovered objects are far larger than those typically found in Orion. While Orion proplyds are nearly symmetric across an axis directed towards the central cluster, the OB2 objects have twisted tails with complex shapes. The objects are 18-113 thousand AU (1 AU = the distance between the Earth and Sun = 93 million miles = 150 million km) across making them significantly larger than the Orion proplyds and even larger than the largest known proplyds in NGC 6303.

Yet as different as they are, the current theoretical understanding of how proplyds work doesn’t put them beyond the plausible range. In particular, the size for a true proplyd is limited by how much stripping it feels from the central stars. Since these objects are further away from OB2-12 and the other massive stars than the Orion proplyds are from the trapezium, they should feel less dispersive forces and should be able to grow as large as is seen. Attempting to pierce the thick dust the objects contain and discover if central stars were present, the team examined the objects in the infrared and radio. Of the ten objects, seven had strong candidates central stellar sources.

Still, the stark differences make conclusively identifying the objects as either EGGs or proplyds difficult. Instead, the authors suggest that these objects may be the first discovery of an inbetween stage: old, highly evolved EGGs which have nearly formed stars making them more akin to young proplyds. If further evidence supports this, this finding would help fill in the scant observational details surrounding stellar formation. This would allow astronomers to more thoroughly test theories which are also tied to the understanding of how planetary systems form.

Posted on by Nancy Atkinson

Clusters of Stars Crackle and Pop to Tell the Story of Star Formation

This enormous section of the Milky Way galaxy is a mosaic of images from NASA's Wide-field Infrared Survey Explorer, or WISE. The constellations Cassiopeia and Cepheus are featured in this 1,000-square degree expanse. Image credit: NASA/JPL-Caltech/UCLA

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Astronomers trying to understand the formation of massive clusters of stars are getting a better idea of how the process works from the latest images and data from the WISE spacecraft. NASA’s Wide-Field Infrared Survey Explorer has captured a vast stretch of nearly a dozen nebulae popping with new star birth, which is helping to narrow the field of possible star-forming scenarios.

“We are trying to understand how huge clusters of stars form at the same time from a large cloud of gas,” said Xavier Koenig from Goddard Space Flight Center, speaking at a press briefing from the American Astronomical Society meeting this week. “We have two possible pictures of how this process works and WISE is helping us piece together the chain of events.”

WISE has mapped the entire sky two times in infrared light, and the astronomers selected a sample of regions to find young stars and map their distributions to try and determine how these large clusters formed. For both possible scenarios, a cluster of stars begin to form at the center of a huge cloud of gas. But what happens next? The first potential situation, called Model 1, is “collect and collapse,” Koenig said, where the stars create a hot bubble of gas which surrounds the stars. “This bubble gathers up material and after a time enough gas builds up that the next generation of stars appears.”

Model 2 is called “chain reaction,” where as bubble of gas progresses outward, stars are continually formed, and there is no gap between the births of stars.

In looking at several of the star-forming nebulae, Koenig and his colleagues noticed a pattern in the spatial arrangement of newborn stars. Some were found lining the blown-out cavities, a phenomenon that had been seen before, but other new stars were seen sprinkled throughout the cavity interiors. The results suggest that stars are born in a successive fashion, one after the other, starting from a core cluster of massive stars and moving steadily outward. This lends support to “chain reaction” star formation theory, and offers new clues about the physics of the process.

The astronomers also found evidence that the bubbles seen in the star-forming clouds can spawn new bubbles. In this scenario, a massive star blasts away surrounding material, which eventually triggers the birth of another star massive enough to carve out its own bubble. A few examples of what may be first- and second-generation bubbles can be seen in the new WISE image.

“Massive stars sweep up and destroy their natal clouds, but they continuously spark new stars to form along the way,” said co-author Dave Leisawitz, the WISE Mission Scientist. “Occasionally a new, massive star forms, perpetuating the sequence of events and giving rise to the dazzling fireworks display seen in this WISE mosaic.”

Since young stars are brighter in infrared, WISE is the perfect telescope to be searching for these massive star-forming regions.
“WISE data is good for this kind of study because the infrared lights up right where these star-forming regions are doing their work – they pop out immediately to your eye,” said Koenig. “I can’t wait to look at more of the WISE sky coverage.”

See a larger version of the new WISE mosaic here.

Sources: JPL, AAS press briefing

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 Nancy Atkinson

Gas, Not Galaxy Collisions Responsible for Star Formation in Early Universe

Artist concept of how a galaxy might accrete mass from rapid, narrow streams of cold gas. These filaments provide the galaxy with continuous flows of raw material to feed its star-forming at a rather leisurely pace. Credit: ESA–AOES Medialab

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Was the universe a kinder, gentler place in the past that we have thought? The Herschel space observatory has looked back across time with its infrared eyes and has seen that galaxy collisions played only a minor role in triggering star births in the past, even though today the birth of stars always seem to be generated by galaxies crashing into each other. So what was the fuel for star formation in the past?

Simple. Gas.

The more gas a galaxy contained, the more stars were born.

Scientists say this finding overturns a long-held assumption and paints a nobler picture of how galaxies evolve.

Astronomers have known that the rate of star formation peaked in the early Universe, about 10 billion years ago. Back then, some galaxies were forming stars ten or even a hundred times more vigorously than is happening in our Galaxy today.

In the nearby, present-day Universe, such high birth rates are very rare and always seem to be triggered by galaxies colliding with each other. So, astronomers had assumed that this was true throughout history.

GOODS-North is a patch of sky in the northern hemisphere that covers an area of about a third the size of the Full Moon. Credit: ESA/GOODS-Herschel consortium/David Elbaz

But Herschel’s observations of two patches of sky show a different story.

Looking at these regions of the sky, each about a third of the size of the full Moon, Herschel has seen more than a thousand galaxies at a variety of distances from the Earth, spanning 80% of the age of the cosmos.

In analyzing the Herschel data, David Elbaz, from CEA Saclay in France, and his team found that even though some galaxies in the past were creating stars at incredible rates, galaxy collisions played only a minor role in triggering star births. The astronomers were able to compare the amount of infrared light released at different wavelengths by these galaxies, the team has shown that the star birth rate depends on the quantity of gas they contain, not whether they are colliding.

They say these observations are unique because Herschel can study a wide range of infrared light and reveal a more complete picture of star birth than ever seen before.

However, their work compliments other recent studies from data from the Spitzer Space Telescope and the Very Large Telescope which found ancient galaxies fed on gas,not collisions

“It’s only in those galaxies that do not already have a lot of gas that collisions are needed to provide the gas and trigger high rates of star formation,” said Elbaz.

Today’s galaxies have used up most of their gaseous raw material after forming stars for more than 10 billion years, so they do rely on collisions to jump-start star formation, but in the past galaxies grew slowly and gently from the gas that they attracted from their surroundings.

This study was part of the GOODS observations with Herschel, the Great Observatories Origins Deep Survey.

Read the team’s paper in Astronomy & Astrophysics: GOODS–Herschel: an infrared main sequence for star-forming galaxies’ by D. Elbaz et al.

Source: ESA

Posted on by Vanessa Janek

Ancient Galaxies Fed On Gas, Not Collisions

The Sombrero Galaxy. Credit: ESO/P. Barthe

[/caption]The traditional picture of galaxy growth is not pretty. In fact, it’s a kind of cosmic cannibalism: two galaxies are caught in ominous tango, eventually melding together in a fiery collision, thus spurring on an intense but short-lived bout of star formation. Now, new research suggests that most galaxies in the early Universe increased their stellar populations in a considerably less violent way, simply by burning through their own gas over long periods of time.

The research was conducted by a group of astronomers at NASA’s Spitzer Science Center in Pasadena, California. The team used the Spitzer Space Telescope to peer at 70 distant galaxies that flourished when the Universe was only 1-2 billion years old. The spectra of 70% of these galaxies showed an abundance of H alpha, an excited form of hydrogen gas that is prevalent in busy star-forming regions. Today, only one out of every thousand galaxies carries such an abundance of H alpha; in fact, the team estimates that star formation in the early Universe outpaced that of today by a factor of 100!

This split view shows how a normal spiral galaxy around our local universe (left) might have looked back in the distant universe, when astronomers think galaxies would have been filled with larger populations of hot, bright stars (right). Image credit: NASA/JPL-Caltech/STScI

Not only did these early galaxies crank out stars much faster than their modern-day counterparts, but they created much larger stars as well. By grazing on their own stores of gas, galaxies from this epoch routinely formed stars up to 100 solar masses in size.

These impressive bouts of star formation occurred over the course of hundreds of millions of years. The extremely long time scales involved suggest that while they probably played a minor role, galaxy mergers were not the main precursor to star formation in the Universe’s younger years. “This type of galactic cannibalism was rare,” said Ranga-Ram Chary, a member of the team. “Instead, we are seeing evidence for a mechanism of galaxy growth in which a typical galaxy fed itself through a steady stream of gas, making stars at a much faster rate than previously thought.” Even on cosmic scales, it would seem that slow and steady really does win the race.

Source: JPL

Posted on by Jon Voisey

Star Forming Density – How Low Can You Go?

Star formation in the Eagle Nebula

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The general picture of star formation envisions stars emerging in clusters, having condensed from cores of gas under self gravity after having passed a critical density threshold. Perhaps the cloud was pushed over the threshold by the shockwave of a supernova or the tidal twisting of a nearby object. How it happens isn’t important since the methods are likely to be many and diverse. What is important is understanding what that threshold is so we may know when it is reached. It is generally referred to as the Jeans mass and observations have generally been well in line with densities predicted by this formulation. However, over the past several years, astronomers have discovered some objects amongst a new class that form in regions and densities not readily explained by the Jeans mass criterion.

The first of this new class, named IRAM 04191, was discovered in 1999 in the Taurus molecular cloud. This object, originally discovered in the radio portion of the spectrum with the Very Large Array, was a tiny forming protostar. The discoverers announced that the object was undergoing gravitational collapse, still disassociating the molecular hydrogen in the cloud from which it formed. While this object fit the traditional picture of star formation it was unique in that it was exceptionally dim. As more of these were discovered, it established a new class of objects that are now being called Very Low Luminosity Objects or VeLLOs.

The launch of the Spitzer infrared telescope allowed for the discovery of more objects. The first one from this telescope was discovered in 2004 and named L1014-IRS. Others have included L1521F-IRS, L328-IRS, and L1148-IRS. These objects are not yet well understood but have the general characteristics of having less than a tenth of the mass of the sun, seem to be accreting heavily (as indicated by outflows), and be only on the order of tens of thousands of years old.

Among these, L1148-IRS has been an oddity. While still low in overall light output, this object was relatively bright in the infrared when compared to other VeLLOs. Studies of the object and its surrounding gas suggested that the object was forming in an unusually empty region, one in which the usual scenario doesn’t seem to fit. A new paper by the original discoverers of this object, suggest that there may be some peculiarities that may be related to this puzzle. In particular, the region doesn’t seem to be collapsing uniformly. Different portions appear to be collapsing at different rates.

Regardless of how this protostar came to collapse, L1148-IRS is an unusual case and expected to form a very low mass star or brown dwarf. Since there are so few VeLLOs, the formation of such early stages of star formation, especially for low mass stars is not well understood and future detection of similar objects will likely greatly contribute to the understanding of low-mass objects in relative isolation.

Posted on by Jason Major

Dust in the Wind

WISE image of the "Elephant Trunk" nebula. NASA/JPL-Caltech/WISE Team.

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The stellar wind, that is! This beautiful image, taken by NASA’s Wide-Field Infrared Explorer (WISE) shows a vast ring of interstellar dust and gas being forced outwards by the wind and radiation from a massive star.

The star, HR8281, is located in the center of the image, the topmost star in a small triangular formation of blue stars to the upper left of the tip of a bright elongated structure – the end of the “elephant trunk” that gives the nebula its name. The star may not look like much, but HR8281’s powerful stellar wind is what’s sculpting the huge cloud of dust into the beautiful shapes seen in this infrared image.

Located 2,450 light-years from Earth, the Elephant’s Trunk Nebula spans 100 light-years. The “trunk” itself is about 30 light-years long. (That’s about, oh… 180 trillion miles!)

Structures like this are common in nebulae. They are formed when the stellar wind – the outpouring of ultraviolet radiation and charged particles that are constantly streaming off stars – blows away the gas and dust near a star, leaving only the densest areas. It’s basically erosion on a massive interstellar scale.

The tip of the "trunk" and the triangle of stars, the topmost of which is HR8281.

It’s not just a destructive process, though. Within those dense areas new stars can form… in fact, in the bright tip of the trunk above a small dark spot can be seen. That’s an area that’s been cleared by the creation of a new star. When a baby star “ignites” and its nuclear fusion factory turns on, its stellar wind clears away the dust and gas in the cloud it was formed from. Nebulae aren’t just pretty clouds in space… they’re stellar nurseries!

The red-colored stars in this image are other newborn stars, still wrapped in their dusty “cocoons”.

The colors used in this image represent specific wavelengths of infrared light. Blue and cyan (blue-green) represent light emitted at wavelengths of 3.4 and 4.6 microns, which is predominantly from stars. Green and red represent light from 12 and 22 microns, respectively, which is mostly emitted by dust.

Read more about this image on the WISE site here.

Image Credit: NASA/JPL-Caltech/WISE Team