Star Formation Archives

November 27, 2013December 23, 2015 by Tammy Plotner

Forging Stars – Peering Into Starbirth and Death

The Large Magellanic Cloud is one of the closest galaxies to our own. Astronomers have now used the power of the ESO’s Very Large Telescope to explore NGC 2035, one of its lesser known regions, in great detail. This new image shows clouds of gas and dust where hot new stars are being born and are sculpting their surroundings into odd shapes. But the image also shows the effects of stellar death — filaments created by a supernova explosion (left). Credit: ESO

Some 160,000 light years away towards the constellation of Dorado (the Swordfish), is an amazing area of starbirth and death. Located in our celestial neighbor, the Large Magellanic Cloud, this huge stellar forge sculpts vast clouds of gas and dust into hot, new stars and carves out ribbons and curls of nebulae. However, in this image taken by ESO’s Very Large Telescope, there’s more. Stellar annihilation also awaits and shows itself as bright fibers left over from a supernova event.

For southern hemisphere observers, one of our nearest galactic neighbors, the Large Magellanic Cloud, is a well-known sight and holds many cosmic wonders. While the image highlights just a very small region, try to grasp the sheer size of what you are looking at. The fiery forge you see is several hundred light years across, and the factory in which it is contained spans 14,000 light years. Enormous? Yes. But compared to the Milky Way, it’s ten times smaller.

Even at such a great distance, the human eye can see many bright regions where new stars are actively forming, such as the Tarantula Nebula. This new image, taken by ESO’s Very Large Telescope at the Paranal Observatory in Chile, explores an area cataloged as NGC 2035 (right), sometimes nicknamed the Dragon’s Head Nebula. But, just what are we looking at?

The Dragon’s Head is an HII region, more commonly referred to as an emission nebula. Here, young stars pour forth energetic radiation and illuminate the surrounding clouds. The radiation tears electrons away from the atoms contained within the gas. These atoms then gel again with other atoms and release light. Swirling in the mix is dark dust, which absorbs the light and creates deep shadows and create contrast in the nebula’s structure.

However, as we look deep into this image, there’s even more… a fiery finale. At the left of the photo you’ll see the results of one of the most violent events in the Universe – a supernova explosion. These troubled tendrils are all that’s left of what once was a star and its name is SNR 0536-67.6. Perhaps when it exploded, it was so bright that it was capable of outshining the Magellanic Cloud… fading away over the weeks or months that followed. However, it left a lasting impression!

Original Story Source: ESO Image Release.

November 18, 2013December 23, 2015 by Elizabeth Howell

‘Elephant Trunks’ Crowd Distant Star Cluster, Raising New Questions About Stellar Formation

NGC 3572 seen with a 2.2-meter telescope at the European Southern Observatory's La Silla Observatory in Chile. Credit: ESO/G. Beccari

Star winds are pushing the gas around NGC 3572 into “elephant trunks”, as you can see if you look carefully as this picture snapped by a La Silla Observatory telescope at the European Southern Observatory in Chile. It’s a demonstration of the power of the youngster blue-white stars embedded in the cloud, which are generating huge gusts blowing the gas and dust away from them.

It’s common for young stars to form in groups. After a few million years growing together, their respective gravities pushes everything further apart, and the stars then finish their lifetimes on their own. Looking at young star clusters such as this gives astronomers a better sense about how our own Sun began its life.

If we zoomed closer to those elephant trunks, they would look similar to the famous “Pillars of Creation” image captured in 1995 by the Hubble Space Telescope in the Eagle Nebula (M16). NASA also did a follow-up observation using infrared wavelengths in 2005 and 2011, which made the young stars a bit easier to see amid the gas and dust.

One of the Hubble Space Telescope's most famous images, the "Pillars of Creation" in the Eagle Nebula. Credit: NASA/ESA — One of the Hubble Space Telescope’s most famous images, the “Pillars of Creation” in the Eagle Nebula. Credit: NASA/ESA

As for the picture of NGC 3572, the high-resolution image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope is also revealing new mysteries that will require further investigation, ESO stated.

“A strange feature captured in this image is the tiny ring-like nebula located slightly above the centre of the image,” ESO wrote. “Astronomers still are a little uncertain about the origin of this curious feature. It is probably a dense leftover from the molecular cloud that formed the cluster, perhaps a bubble created around a very bright hot star. But some authors have considered that it may be some kind of oddly shaped planetary nebula — the remnants of a dying star.”

Astronomers were also surprised by seeing stars older than 10 million years old within this image that were still picking up mass, which implies that planetary formation could take longer than previously believed.

Research was led by ESO astronomer Giacomo Beccari.

Source: European Southern Observatory

November 12, 2013December 23, 2015 by Elizabeth Howell

Supersonic Starbirth Bubble Glows In Image From Two Telescopes

Stellar birth is visible in this image of HH 46/47 taken with the Spitzer Space Telescope and Atacama Large Millimeter/submillimeter Array (ALMA). Credit: NASA/JPL-Caltech/ALMA

Talk about birth in the fast lane. Fresh observations of HH 46/47 — an area well-known for hosting a baby star — demonstrate material from the star pushing against the surrounding gas at supersonic speeds.

“HH” stands for Herbig-Haro, a type of object created “when jets shot out by newborn stars collide with surrounding material, producing small, bright, nebulous regions,” NASA stated. It’s a little hard to see what’s inside these regions, however, as they’re clouded by debris (specifically, gas and dust).

The Spitzer space telescope (which looks in infrared) and the massive Chilean Atacama Large Millimeter/submillimeter Array (ALMA) are both designed to look through the stuff to see what’s within. Here’s what they’ve spotted:

– ALMA: The telescope is showing that the gas is moving apart faster than ever believed, which could have echoes on how the star cloud is forming generally. “In turn, the extra turbulence could have an impact on whether and how other stars might form in this gaseous, dusty, and thus fertile, ground for star-making,” NASA added.

Another view of HH 46/47 with the Atacama Large Millimeter/submillimeter Array (ALMA). Credit: ESO/ALMA (ESO/NAOJ/NRAO)/H. Arce. Acknowledgements to Bo Reipurth

– Spitzer: Two supersonic blobs are emerging from the star in the middle and pushing against the gas, creating the big bubbles you can see here. The right-aiming blob has a lot more material to push through than the left one, “offering a handy compare-and-contrast setup for how the outflows from a developing star interact with their surroundings,” NASA stated.

“Young stars like our sun need to remove some of the gas collapsing in on them to become stable, and HH 46/47 is an excellent laboratory for studying this outflow process,” stated Alberto Noriega-Crespo, a scientist at the Infrared Processing and Analysis Center at the California Institute of Technology.

“Thanks to Spitzer, the HH 46/47 outflow is considered one of the best examples of a jet being present with an expanding bubble-like structure.”

The ALMA observations of HH 46/47 were first revealed in detail this summer, in an Astrophysical Journal publication.

Source: NASA

November 6, 2013December 23, 2015 by Jason Major

Early Supermassive Black Holes First Formed as Twins

Two nascent black holes formed by the collapse of an early supergiant star. From a visualization by by Christian Reisswig (Caltech).

It’s one of the puzzles of cosmology and stellar evolution: how did supermassive black holes get so… well, supermassive… in the early Universe, when seemingly not enough time had yet passed for them to accumulate their mass through steady accretion processes alone? It takes a while to eat up a billion solar masses’ worth of matter, even with a healthy appetite and lots within gravitational reach. But yet there they are: monster black holes are common within some of the most distant galaxies, flaunting their precocious growth even as the Universe was just celebrating its one billionth birthday.

Now, recent findings by researchers at Caltech suggest that these ancient SMBs were formed by the death of certain types of primordial giant stars, exotic stellar dinosaurs that grew large and died young. During their violent collapse not just one but two black holes are formed, each gathering its own mass before eventually combining together into a single supermassive monster.

Watch a simulation and find out more about how this happens below:

From a Caltech news article by Jessica Stoller-Conrad:

To investigate the origins of young supermassive black holes, Christian Reisswig, NASA Einstein Postdoctoral Fellow in Astrophysics at Caltech and Christian Ott, assistant professor of theoretical astrophysics, turned to a model involving supermassive stars. These giant, rather exotic stars are hypothesized to have existed for just a brief time in the early Universe.

Unlike ordinary stars, supermassive stars are stabilized against gravity mostly by their own photon radiation. In a very massive star, photon radiation—the outward flux of photons that is generated due to the star’s very high interior temperatures—pushes gas from the star outward in opposition to the gravitational force that pulls the gas back in.

During its life, a supermassive star slowly cools due to energy loss through the emission of photon radiation. As the star cools, it becomes more compact, and its central density slowly increases. This process lasts for a couple of million years until the star has reached sufficient compactness for gravitational instability to set in and for the star to start collapsing gravitationally.

Previous studies predicted that when supermassive stars collapse, they maintain a spherical shape that possibly becomes flattened due to rapid rotation. This shape is called an axisymmetric configuration. Incorporating the fact that very rapidly spinning stars are prone to tiny perturbations, Reisswig and his colleagues predicted that these perturbations could cause the stars to deviate into non-axisymmetric shapes during the collapse. Such initially tiny perturbations would grow rapidly, ultimately causing the gas inside the collapsing star to clump and to form high-density fragments.

“The growth of black holes to supermassive scales in the young universe seems only possible if the ‘seed’ mass of the collapsing object was already sufficiently large.”

– Christian Reisswig, NASA Einstein Postdoctoral Fellow at Caltech

Composite image from Chandra and Hubble showing supermassive black holes in the early Universe.

These fragments would orbit the center of the star and become increasingly dense as they picked up matter during the collapse; they would also increase in temperature. And then, Reisswig says, “an interesting effect kicks in.” At sufficiently high temperatures, there would be enough energy available to match up electrons and their antiparticles, or positrons, into what are known as electron-positron pairs. The creation of electron-positron pairs would cause a loss of pressure, further accelerating the collapse; as a result, the two orbiting fragments would ultimately become so dense that a black hole could form at each clump. The pair of black holes might then spiral around one another before merging to become one large black hole.

“This is a new finding,” Reisswig says. “Nobody has ever predicted that a single collapsing star could produce a pair of black holes that then merge.”

These findings were published in Physical Review Letters the week of October 11. Source: Caltech news article by Jessica Stoller-Conrad.

September 25, 2013December 23, 2015 by Tammy Plotner

New Camera Aboard APEX Gets First Light

This image of the star formation region NGC 6334 is one of the first scientific images from the ArTeMiS instrument on APEX. The picture shows the glow detected at a wavelength of 0.35 millimetres coming from dense clouds of interstellar dust grains. The new observations from ArTeMiS show up in orange and have been superimposed on a view of the same region taken in near-infrared light by ESO’s VISTA telescope at Paranal. Credit: ArTeMiS team/Ph. André, M. Hennemann, V. Revéret et al./ESO/J. Emerson/VISTA Acknowledgment: Cambridge Astronomical Survey Unit

And the “Cat’s Paw” was waiting to strike! In this exceptionally detailed image of star-forming region NGC 6334 we can get a sense of just how important new instrumentation can be. In this case it’s a new camera called ArTeMiS and it has just been installed on a 12-meter diameter telescope located high in the Atacama Desert. The Atacama Pathfinder Experiment – or APEX for short – operates at millimeter and submillimeter wavelengths, providing us with observations ranging between radio wavelengths and infrared light. These images give astronomers powerful new data to help them further understand the construction of the Universe.

Exactly what is ArTeMiS? The camera provides wide field views at submillimeter wavelengths. When added to APEX’s arsenal, it will substantially increase the amount of details a particular object has to offer. It has a detector array similar to a CCD camera – a new technology which will enable it to create wide-field maps of target areas with a greater amount of speed and a larger amount of pixels.

Like almost all new telescope projects, both personal and professional, the APEX team met up with “first light” problems. Although the ArTeMiS Camera was ready to go, the weather simply wouldn’t cooperate. According to the news release, very heavy snow on the Chajnantor Plateau had almost buried the building in which the scope operations are housed! However, the team was determined. Using a makeshift road and dodging snow drifts, the team and the staff at the ALMA Operations Support Facility and APEX somehow managed to get the camera to its location safely. Undaunted, they installed the ArTeMiS camera, worked the cryostat into position and locked the instrumentation down in its final position.

However, digging their way out of the snow wasn’t all the team had to contend with. To get ArTeMis on-line, they then had to wait for very dry weather since submillimeter wavelengths of light are highly absorbed by atmospheric moisture. Do good things come to those who wait? You bet. When the “magic moment” arrived, the APEX team was ready and the initial test observations were a resounding success. ArTeMiS quickly became the focus tool for a variety of scientific projects and commissioned observations. One of these projects was to image star-forming region NGC 6334 – the Cat’s Paw Nebula – in the southern constellation of Scorpius. Thanks to the new technology, the ArTeMiS image shows a superior amount of detail over earlier photographic observations taken with APEX.

What’s next for ArTeMiS? Now that the camera has been tested, it will be returned to Saclay in France to have even more detectors installed. According to the researchers: ” The whole team is already very excited by the results from these initial observations, which are a wonderful reward for many years of hard work and could not have been achieved without the help and support of the APEX staff.”

Original Story Source: ESO Public News Release.

July 17, 2013December 23, 2015 by Jason Major

Earth’s Gold Came From Colliding Stars

Collisions of neutron stars produce powerful gamma-ray bursts – and heavy elements like gold (Credit: Dana Berry, SkyWorks Digital, Inc.)

Are you wearing a gold ring? Or perhaps gold-plated earrings? Maybe you have some gold fillings in your teeth… for that matter, the human body itself naturally contains gold — 0.000014%, to be exact! But regardless of where and how much of the precious yellow metal you may have with you at this very moment, it all ultimately came from the same place.

And no, I don’t mean Fort Knox, the jewelry store, or even under the ground — all the gold on Earth likely originated from violent collisions between neutron stars, billions of years in the past.

Recent research by scientists at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts has revealed that considerable amounts of gold — along with other heavy elements — are produced during impacts between neutron stars, the super-dense remains of stars originally 1.4 to 9 times the mass of our Sun.

The team’s investigation of a short-duration gamma-ray outburst that occurred in June (GRB 130603B) showed a surprising residual near-infrared glow, possibly from a cloud of material created during the stellar merger. This cloud is thought to contain a considerable amount of freshly-minted heavy elements, including gold.

“We estimate that the amount of gold produced and ejected during the merger of the two neutron stars may be as large as 10 moon masses – quite a lot of bling!” said lead author Edo Berger.

"With this remnant of a dead neutron star, I thee wed." (FreeDigitalPhotos.net/bigjom) — “With this remnant of a dead neutron star, I thee wed.” (FreeDigitalPhotos.net/bigjom)

The mass of the Moon is 7.347 x 10²² kg… about 1.2% the mass of Earth. The collision between these neutron stars then, 3.9 billion light-years away, produced 10 times that much gold based on the team’s estimates.

Quite a lot of bling, indeed.

Gamma-ray bursts come in two varieties – long and short – depending on the duration of the gamma-ray flash. GRB 130603B, detected by NASA’s Swift satellite on June 3rd, lasted for less than two-tenths of a second.

Although the gamma rays disappeared quickly, GRB 130603B also displayed a slowly fading glow dominated by infrared light. Its brightness and behavior didn’t match the typical “afterglow” created when a high-speed jet of particles slams into the surrounding environment.

Instead, the glow behaved like it came from exotic radioactive elements. The neutron-rich material ejected by colliding neutron stars can generate such elements, which then undergo radioactive decay, emitting a glow that’s dominated by infrared light – exactly what the team observed.

“We’ve been looking for a ‘smoking gun’ to link a short gamma-ray burst with a neutron star collision,” said Wen-fai Fong, a graduate student at CfA and a co-author of the paper. “The radioactive glow from GRB 130603B may be that smoking gun.”

The team calculates that about one-hundredth of a solar mass of material was ejected by the gamma-ray burst, some of which was gold. By combining the estimated gold produced by a single short GRB with the number of such explosions that have likely occurred over the entire age of the Universe, all the gold in the cosmos – and thus on Earth – may very well have come from such gamma-ray bursts.

Watch an animation of two colliding neutron stars along with the resulting GRB below (Credit: Dana Berry, SkyWorks Digital, Inc.):

How much gold is there on Earth, by the way? Since most of it lies deep inside Earth’s core and is thus unreachable, the total amount ever retrieved by humans over the course of history is surprisingly small: about 172,000 tonnes, or enough to make a cube 20.7 meters (68 feet) per side (based on the Thomson Reuters GFMS annual survey.) Some other estimates put this amount at slightly more or less, but the bottom line is that there really isn’t all that much gold available in Earth’s crust… which is partly what makes it (and other “precious” metals) so valuable.

And perhaps the knowledge that every single ounce of that gold was created by dead stars smashing together billions of years ago in some distant part of the Universe would add to that value.

“To paraphrase Carl Sagan, we are all star stuff, and our jewelry is colliding-star stuff,” Berger said.

The team’s findings were presented today in a press conference at the CfA in Cambridge. (See the paper here.)

Source: Harvard-Smithsonian CfA

July 12, 2013December 23, 2015 by Shannon Hall

Jets Boost — Not Hinder — Star Formation in Early Galaxies, New Study Suggests

An artist's conception of jets protruding from a quasar. Credit: ESO/M. Kornmesser

Understanding the formation of stars and galaxies early in the Universe’s history continues to be somewhat of an enigma, and a new study may have turned our current understanding on its head. A recent survey used archival data from four different telescopes to analyze hundreds of galaxies. The results provided overwhelming evidence that radio jets protruding from a galactic center enhance star formation – a result that directly contradicts current models, where star formation is hindered or even stopped.

All early galaxies consist of intensely luminous cores powered by huge black holes. These so-called active galactic nuclei, or AGN for short, are still the topic of intense study. One specific mechanism astronomers are studying is known as AGN feedback.

“Feedback is the astronomer’s slang term for the way in which an AGN – with its large amount of energy release – influences its host galaxy,” Dr. Zinn, lead researcher on this study, recently told Universe Today. He explained there is both positive feedback, in which the AGN will foster the main activity of the galaxy: star formation, and negative feedback, in which the AGN will hinder or even stop star formation.

Current simulations of galaxy growth invoke strong negative feedback.

“In most cosmological simulations, AGN feedback is used to truncate star formation in the host galaxy,” said Zinn. “This is necessary to prevent the simulated galaxies from becoming too bright/massive.”

Zinn et al. found strong evidence that this is not the case for a large number of early galaxies, claiming that the presence of an AGN actually enhances star formation. In such cases the total star formation rate of a galaxy may be boosted by a factor of 2 – 5.

Furthermore the team showed that positive feedback occurs in radio-luminous AGN. There is strong correlation between the far infrared (indicative of star formation) and the radio.

Now, a correlation between the radio and the far infrared is no stranger to galactic astronomy. Stars form in extremely dusty regions. This dust absorbs the starlight and re-emits it in the far infrared. The stars then die in huge supernova explosions, causing powerful shock-fronts, which accelerate electrons and lead to the emission of strong synchrotron radiation in the radio.

This correlation however is a stranger to AGN studies. The key lies in the radio jets, which penetrate far into the host galaxy itself. A “jet which is launched from the AGN hits the interstellar gas of the host galaxy and thereby induces supersonic shocks and turbulence,” explains Zinn. “This shortens the clumping time of gas so that it can condense into stars much more quick and efficiently.”

This new finding conveys that the exact mechanisms in which AGN interact with their host galaxies is much more complicated than previously thought. Future observations will likely shed a new understanding of the evolution of galaxies.

The team used data primarily from the Chandra Deep Field South image
but also data from Hubble, Herschel and Spitzer.

The results will be published in the Astrophysical Journal (preprint available here).

July 10, 2013December 23, 2015 by Jason Major

ALMA Spots a Nascent Stellar Monster

ALMA/Spitzer image of a monster star in the process of forming

Even though it comprises over 99% of the mass of the Solar System (with Jupiter taking up most of the rest) our Sun is, in terms of the entire Milky Way, a fairly average star. There are lots of less massive stars than the Sun out there in the galaxy, as well as some real stellar monsters… and based on new observations from the Atacama Large Millimeter/submillimeter Array, there’s about to be one more.

Early science observations with ALMA have provided astronomers with the best view yet of a monster star in the process of forming within a dark cloud of dust and gas. Located 11,000 light-years away, Spitzer Dark Cloud 335.579-0.292 is a stellar womb containing over 500 times the mass of the Sun — and it’s still growing. Inside this cloud is an embryonic star hungrily feeding on inwardly-flowing material, and when it’s born it’s expected to be at least 100 times the mass of our Sun… a true stellar monster.

The location of SDC 335.579-0.292 in the southern constellation of Norma (ESO, IAU and Sky & Telescope)

The star-forming region is the largest ever found in our galaxy.

“The remarkable observations from ALMA allowed us to get the first really in-depth look at what was going on within this cloud,” said Nicolas Peretto of CEA/AIM Paris-Saclay, France, and Cardiff University, UK. “We wanted to see how monster stars form and grow, and we certainly achieved our aim! One of the sources we have found is an absolute giant — the largest protostellar core ever spotted in the Milky Way.”

Watch: What’s the Biggest Star in the Universe?

SDC 335.579-0.292 had already been identified with NASA’s Spitzer and ESA’s Herschel space telescopes, but it took the unique sensitivity of ALMA to observe in detail both the amount of dust present and the motion of the gas within the dark cloud, revealing the massive embryonic star inside.

“Not only are these stars rare, but their birth is extremely rapid and their childhood is short, so finding such a massive object so early in its evolution is a spectacular result.”

– Team member Gary Fuller, University of Manchester, UK

The image above, a combination of data acquired by both Spitzer and ALMA (see below for separate images) shows tendrils of infalling material flowing toward a bright center where the huge protostar is located. These observations show how such massive stars form — through a steady collapse of the entire cloud, rather than through fragmented clustering.

SDC 335.579-0.292 seen in different wavelengths of light.

“Even though we already believed that the region was a good candidate for being a massive star-forming cloud, we were not expecting to find such a massive embryonic star at its center,” said Peretto. “This object is expected to form a star that is up to 100 times more massive than the Sun. Only about one in ten thousand of all the stars in the Milky Way reach that kind of mass!”

(Although, with at least 200 billion stars in the galaxy, that means there are still 20 million such giants roaming around out there!)

Astronomers Spy Early Galaxies Caught In A Cosmic Spiderweb

The Spiderweb, imaged by the Hubble Space Telescope – a central galaxy (MRC 1138-262) surrounded by hundreds of other star-forming 'clumps'. Credit: NASA, ESA, George Miley and Roderik Overzier (Leiden Observatory)

Once upon a time, when the Universe was just about three billion years old, galaxies started to form. Now astronomers using a CSIRO radio telescope have captured evidence of the raw materials these galaxies used to fashion their first stars… cold molecular hydrogen gas, H2. Even though we can’t see it directly, we know it is there by using another gas that reveals its presence – carbon monoxide (CO) – a radio wave emitter.

The telescope is CSIRO’s Australia Telescope Compact Array telescope near Narrabri, NSW. “It one of very few telescopes in the world that can do such difficult work, because it is both extremely sensitive and can receive radio waves of the right wavelengths,” says CSIRO astronomer Professor Ron Ekers.

One of the studies of these “raw” galaxies was performed by astronomer Dr. Bjorn Emonts of CSIRO Astronomy and Space Science. He and fellow researchers employed the Compact Array to observe and record a gigantic and distant amalgamation of “star forming clumps or proto-galaxies” which are congealing together to create a single massive galaxy. This framework is known as the “Spiderweb” and is theorized to be at least ten thousand million light years distant. The Compact Array radio telescope is capable of picking up the signature of star formation, giving astronomers vital clues about how early galaxies began star formation.

In blue, the carbon monoxide gas detected in and around the Spiderweb. Credit: B. Emonts et al (CSIRO/ATCA)

The “Spiderweb” was loaded. Here Dr. Emont and his colleagues found the molecular hydrogen gas fuel they were seeking. It covered an area of space almost a quarter of a million light-years across and contained at least sixty thousand million times the mass of the Sun! Surely this had to be the material responsible for the new stars seen sprinkled across the region. “Indeed, it is enough to keep stars forming for at least another 40 million years,” says Emonts.

In another research project headed by Dr. Manuel Aravena of the European Southern Observatory, the scientists measured the CO – the indicator of H2 – in two very distant galaxies. The signal of the faint radio waves was amped up by the gravitational fields of the additional galaxies – the “line of sight” members – which created gravitational lensing. Says Dr. Aravena, “This acts like a magnifying lens and allows us to see even more distant objects than the Spiderweb.”

Dr. Aravena’s team went to work measuring the amount of H2 in both of their study galaxies. One of these, SPT-S 053816-5030.8, produced enough radio emissions to allow them to infer how quickly it was forming stars – “an estimate independent of the other ways astronomers measure this rate.”

The Compact Array was tuned in. Thanks to an upgrade which increased its bandwidth – the amount of the radio spectrum which can be observed at any particular time – it is now sixteen times stronger and capable of reaching a range from 256 MHz to 4 GHz. That makes it a very sensitive ear!

“The Compact Array complements the new ALMA telescope in Chile, which looks for the higher-frequency transitions of CO,” says Ron Ekers.

Original Story Source: CSIRO News Release

June 11, 2013December 23, 2015 by Nancy Atkinson

Space Observatories Watch a Black Hole Go Dormant

The Sculptor galaxy is seen in a new light, in this composite image from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Southern Observatory in Chile. Image credit: NASA/JPL-Caltech/JHU

The Chandra X-ray Observatory has been keeping an eye on a black hole actively munching away on gas at the middle of the nearby Sculptor galaxy. Now, with the added eyes of the Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, the observatories have found the black hole has fallen asleep, even amid rampant star-formation going on around it.

“Our results imply that the black hole went dormant in the past 10 years,” said Bret Lehmer of the Johns Hopkins University, Baltimore, and NASA’s Goddard Space Flight Center. “Periodic observations with both Chandra and NuSTAR should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching.”

Lehmer is lead author of a new study detailing the findings in the Astrophysical Journal.

The now-latent black hole is about 5 million times the mass of our Sun. The Sculptor galaxy (NGC 253) is a so-called starburst galaxy, which is actively giving birth to new stars. At just 13 million light-years away, it is one of the closest starbursts galaxies to us.

Why did the black hole go dormant?

“Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant,” said co-author Ann Hornschemeier of Goddard. “NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it.”

“Black hole growth and star formation often go hand-in-hand in distant galaxies,” added Daniel Stern, a co-author and NuSTAR project scientist at the Jet Propulsion Laborator. “It’s a bit surprising as to what’s going on here, but we’ve got two powerful complementary X-ray telescopes on the case.”

Chandra first observed signs of what appeared to be a feeding supermassive black hole at the heart of the Sculptor galaxy in 2003. Then, in September and November of 2012, Chandra and NuSTAR observed the same region simultaneously. NuSTAR, which launched in June of 2012, detected focused, high-energy X-ray light from the region, allowing the researchers to say conclusively that the black hole is not accreting material.

There are two possibilities: either the black hole has in fact gone dormant, or another possibility is that the black hole was not actually awake 10 years ago, and Chandra observed a different source of X-rays. Future observations with both telescopes may solve the puzzle.

The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this,” said Lou Kaluzienski, NuSTAR Program Scientist at NASA Headquarters in Washington. “Now, we can get all sides of the story.”

NuSTAR launched into space in June of 2012.

If and when the Sculptor’s slumbering giant does wake up in the next few years amidst all the commotion, NuSTAR and Chandra will monitor the situation. The team plans to check back on the system periodically.

Source: JPL