Infrared Astronomy Archives

September 19, 2011December 24, 2015 by Tammy Plotner

Did Asteroid Baptistina Kill The Dinosaurs? Think Other WISE…

It's long been thought that a giant asteroid, which broke up long ago in the main asteroid belt between Mars and Jupiter, eventually made its way to Earth and led to the extinction of the dinosaurs. New studies say that the dinosaurs may have been facing extinction before the asteroid strike, and that mammals were already on the rise. Image credit: NASA/JPL-Caltech

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Once upon a time, about 65 million years ago, scientists hypothesize a sizable asteroid crashed into Earth and contributed to the extinction of the dinosaurs. The evidence is a 150-kilometer-wide crater located just off the Yucatan peninsula and legend has it the 10-kilometer-wide asteroid was a fragment of a larger parent – Baptistina. Now, thanks to observations by NASA’s Wide-field Infrared Survey Explorer (WISE), we just might have to re-think that theory.

While there’s almost absolutely no doubt an asteroid crash was responsible for a cataclysmic climate change, science has never been particularly sure of what asteroid caused it. A visible-light study done by terrestrial telescopes in 2007 pointed a finger at a huge asteroid known as Baptistina. The conjecture was that about 160 million years ago, it collided with another main belt asteroid and sent pieces flying. Even though it was plausible, the theory was quickly challenged and now infra-red evidence from WISE may finally lay this family of asteroids to rest.

“As a result of the WISE science team’s investigation, the demise of the dinosaurs remains in the cold case files,” said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program at NASA Headquarters in Washington. “The original calculations with visible light estimated the size and reflectivity of the Baptistina family members, leading to estimates of their age, but we now know those estimates were off. With infrared light, WISE was able to get a more accurate estimate, which throws the timing of the Baptistina theory into question.”

For over a year, WISE took an infra-red survey of the entire sky and asteroid-hunting portion of the mission, called NEOWISE, cataloged 157,000 members – discovering an additional 33,000 new ones. By utilizing the more accurate infra-red data, the team examined 1,056 members of the Baptistina family and discovered its break-up was closer to 80 million years ago – less than half the time previously suggested. By better knowing their size and reflectivity, researchers are able to calculate how long it would take for Baptistina members to reach their current position. The results show that in order for this particular asteroid to have caused an extinction level event, that it would have had to have impacted Earth much sooner… like about 15 million years.

“This doesn’t give the remnants from the collision very much time to move into a resonance spot, and get flung down to Earth 65 million years ago,” said Amy Mainzer, a study co-author and the principal investigator of NEOWISE at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena. Calif. “This process is thought to normally take many tens of millions of years.”

Like bouncing a super ball off the walls, resonance spots can jettison asteroids out of the main belt. This means a dinosaur-killing Baptistina event isn’t likely, but other asteroid families in NEOWISE study show similar reflective properties and one day we may be able to locate a responsible party.

“We are working on creating an asteroid family tree of sorts,” said Joseph Masiero, the lead author of the study. “We are starting to refine our picture of how the asteroids in the main belt smashed together and mixed up.”

Original Story Source: JPL/NASA News.

September 18, 2011April 26, 2016 by Jason Major

“Pluto-Killer” Sets Sights on Neptune

Infrared image of Neptune from Keck Observatory in Hawaii. Credit: Mike Brown/CalTech

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The confessed (and remorseless) “Pluto Killer” Mike Brown has turned his gaze – and the 10-meter telescope at the Keck Observatory in Hawaii – on Neptune, our solar system’s furthest “official” planet. But no worries for Neptune – Mike isn’t after its planetary status… he’s taken some beautiful infrared images instead!

Normally only visible as a featureless blue speck in telescopes, Brown’s image of Neptune — along with its largest moon Triton — shows the icy gas giant in infrared light, glowing bright red and orange.

Brown’s initial intention was not just to get some pretty pictures of planets. The target of the imaging mission was Triton and to learn more about the placement of its methane, nitrogen and seasonal frosts, and this sort of research required infrared imaging. Of course, Neptune turned out to be quite photogenic itself.

“The big difference is doing the imaging in the infrared where methane absorbs most of the photons,” said Brown. “So the bright places are high clouds where the sunlight reflects off of them before it had a chance to pass through much of the atmosphere. Dark is clear atmosphere full of methane absorption.

“I just thought it was so spectacular that I should post it.”

No argument here, Mike!

Neptune, now officially the outermost planet in our solar system, is the fourth largest planet and boasts the highest wind speeds yet discovered — 1,250 mph winds scream around its frigid skies! Like the other gas giants Neptune has a system of rings, although nowhere near as extravagant as Saturn’s. It has 13 known moons, of which Triton is the largest.

With its retrograde orbit, Triton is believed to be a captured Kuiper Belt Object now in orbit around Neptune. Kuiper Belt Objects are Mike Brown’s specialty, as he is the astronomer most well-known for beginning the whole process that got Pluto demoted from the official planet list back in 2006.

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

September 2, 2011December 24, 2015 by Jason Rhian

James Webb Space Telescope Nearing Completion

The James Webb Space Telescope. Image Credit: NASA/JPL

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The James Webb Space Telescope or JWST has long been touted as the replacement for the Hubble Space Telescope. The telescope is considered to be the one of the most ambitious space science projects ever undertaken – this complexity may be its downfall. Cost overruns now threaten the project with cancellation. Despite these challenges, the telescope is getting closer to completion. As it stands now, the telescope has served as a technical classroom on the intricacies involved with such a complex project. It has also served to develop new technologies that are used by average citizens in their daily lives.

Although compared to Hubble, the two telescopes are dissimilar in a number of ways. The JWST is three times as powerful as Hubble in its infrared capabilities. JWST’s primary mirror is 21.3 feet across (this provides about seven times the amount of collecting power that Hubble currently employs).

The JWST’s mirrors were polished using computer modeling guides that allowed engineers to predict that they will enter into the proper alignment when in space. Each of the mirrors on the JWST has been smoothed down to within 1/1000th the thickness of a human hair. The JWST traveled to points across the country to assemble and test the JWST’s various components.

Eventually the mirrors were then sent to NASA’s Marshall Space Flight Center in Huntsville, Alabama. Once there they measured how the mirrors reacted at extremely cold temperatures. With these tests complete, the mirrors were given a thin layer of gold. Gold is very efficient when it comes to reflecting light in the infrared spectrum toward the JWST’s sensors.

jwst1 — A comparison of the primary mirror used by Hubble and the primary mirror array used by the James Webb Space Telescope. Photo Credit: NASA

The telescope’s array of mirrors is comprised of beryllium, which produces a lightweight and more stable form of glass. The JWST requires lightweight yet strong mirrors so that they can retain their shape in the extreme environment of space. These mirrors have to be able to function perfectly in temperatures reaching minus 370 degrees Fahrenheit.

After all of this is done, still more tests await the telescope. It will be placed into the same vacuum chamber that tested the Apollo spacecraft before they were sent on their historic mission’s to the moon. This will ensure that the telescopes optics will function properly in a vacuum.

175675main_JWSTModel_lg — A life-sized model of the JWST was placed on display in Seattle, Washington - it was several stories tall and weighed several tons. Photo Credit: Rob Gutro/ NASA

With all of the effort placed into the JWST – a lot of spinoff technology was developed that saw its way into the lives of the general populace. Several of these – had to be invented prior to the start of the JWST program.

“Ten technologies that are required for JWST to function did not exist when the project was first planned, and all have been successfully achieved. These include both near and mid-infrared detectors with unprecedented sensitivity, the sunshield material, the primary mirror segment assembly, the NIRSpec microshutter array, the MIRI cryo-cooler, and several more,” said the James Webb Space Telescope’s Deputy Project Scientist Jason Kalirai. Kalirai holds a PhD in astrophysics and carries out research for the Space Telescope Science Institute. “The new technologies in JWST have led to many spinoffs, including the production of new electric motors that outperform common gear boxes, design for high precision optical elements for cameras and cell phones, and more accurate measurements of human vision for people about to undergo Laser Refractive Surgery.”

The James Webb Space Telescope encapsulated atop the Ariane V rocket tapped launch it, next to an early image of the telescope. Image Credit: NASA

If all goes according to plan, the James Webb Space Telescope will be launched from French Guiana atop the European Space Agency’s Arianne V Rocket. The rationale behind the Ariane V’s selection was based on capabilities – and economics.

“The Ariane V was chosen as the launch vehicle for JWST at the time because there was no U.S. rocket with the required lift capacity,” Kalirai said. “Even today, the Ariane V is a better tested vehicle. Moreover, the Ariane is provided at no cost by the Europeans while we would have had to pay for a U.S. rocket.”

It still remains to be seen as to whether or not the JWST will even fly. As of July 6 of this year the project is slated to be cancelled by the United States Congress. The James Webb Space Telescope was initially estimated at costing $1.6 billion. As of this writing an estimated $3 billion has been spent on the project and it is has been estimated that the telescope is about three-quarters complete.

August 24, 2011December 24, 2015 by Tammy Plotner

WISE Discovers Some Really “Cool” Stars!

This artist's conception illustrates what a "Y dwarf" might look like. Y dwarfs are the coldest star-like bodies known. Image credit: NASA/JPL-Caltech

[/caption]What would you say if I told you there are stars with a temperature close to that of a human body? Before you have me committed, there really is such a thing. These “cool” stars belong to the brown dwarf family and are termed Y dwarfs. For over ten years astronomers have been hunting for these dark little beasties with no success. Now infrared data from NASA’s Wide-field Infrared Survey Explorer (WISE) has turned up six of them – and they’re less than 40 light years away!

“WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision,” said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “They are 5,000 times brighter at the longer infrared wavelengths WISE observed from space than those observable from the ground.”

Often referred to as “failed stars”, the Y-class suns are simply too low mass to ignite the fusion process which makes other stars shine in visible light. As they age, they fade away – their only signature is what can be spotted in infrared. The brown dwarfs are of great interest to astronomers because we can gain a better understanding as to stellar natures and how planetary atmospheres form and evolve. Because they are alone in space, it’s much easier to study these Jupiter-like suns… without being blinded by a parent star.

“Brown dwarfs are like planets in some ways, but they are in isolation,” said astronomer Daniel Stern, co-author of the Spitzer paper at JPL. “This makes them exciting for astronomers — they are the perfect laboratories to study bodies with planetary masses.”

The WISE mission has been extremely productive – turning up more than 100 brown dwarf candidates. Scientists are hopeful that even more will emerge as huge amounts of data are processed from the most advanced survey of the sky at infrared wavelengths to date. Just imagine how much information was gathered from January 2010 to February 2011 as the telescope scanned the entire sky about 1.5 times! One of the Y dwarfs, called WISE 1828+2650, is the record holder for the coldest brown dwarf, with an estimated atmospheric temperature cooler than room temperature, or less than about 80 degrees Fahrenheit (25 degrees Celsius).

“The brown dwarfs we were turning up before this discovery were more like the temperature of your oven,” said Davy Kirkpatrick, a WISE science team member at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, Calif. “With the discovery of Y dwarfs, we’ve moved out of the kitchen and into the cooler parts of the house.”

Kirkpatrick is the lead author of a paper appearing in the Astrophysical Journal Supplement Series, describing the 100 confirmed brown dwarfs. Michael Cushing, a WISE team member at NASA’s Jet Propulsion Laboratory in Pasadena, California, is lead author of a paper describing the Y dwarfs in the Astrophysical Journal.

“Finding brown dwarfs near our Sun is like discovering there’s a hidden house on your block that you didn’t know about,” Cushing said. “It’s thrilling to me to know we’ve got neighbors out there yet to be discovered. With WISE, we may even find a brown dwarf closer to us than our closest known star.”

Given the nature of the Y-class stars, positively identifying these special brown dwarfs wasn’t an easy task. For that, the WISE team employed the aid of the Spitzer Space Telescope to refine the hunt. From there the team used the most powerful telescopes on Earth – NASA Infrared Telescope Facility atop Mauna Kea, Hawaii; Caltech’s Palomar Observatory near San Diego; the W.M. Keck Observatory atop Mauna Kea, Hawaii; and the Magellan Telescopes at Las Campanas Observatory, Chile, and others – to look for signs of methane, water and even ammonia. For the very coldest of the new Y dwarfs, the team used NASA’s Hubble Space Telescope. Their final answer came when changes in spectra indicated a low temperature atmosphere – and a Y-class signature.

“WISE is looking everywhere, so the coolest brown dwarfs are going to pop up all around us,” said Peter Eisenhardt, the WISE project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, California, and lead author of a recent paper in the Astronomical Journal on the Spitzer discoveries. “We might even find a cool brown dwarf that is closer to us than Proxima Centauri, the closest known star.”

How cool is that?!

Original Story Source: JPL News Release.

August 11, 2011December 24, 2015 by Tammy Plotner

Graphenes In Spaaaaaace!

Artist’s impression of the graphenes (C24) and fullerenes found in a Planetary Nebula. The detection of graphenes and fullerenes around old stars as common as our Sun suggests that these molecules and other allotropic forms of carbon may be widespread in space. Credits: IAC; original image of the Helix Nebula (NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner, STScI, & T.A. Rector, NRAO.)

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And just where have your buckyballs been lately? More technically known as fullerenes, this magnetic form of carbon shows some pretty interesting properties deduced from laboratory work here on Earth. But even more interesting is its cousin – graphene. And guess where it’s been found?!

When you picture a fullerene, you conjure up a mental image of carbon atoms arranged in a three-dimensional configuration with two structures: C60 which patterns out similar to a soccer ball and C70 which more closely resembles a rugby ball. Both of these types of “buckyballs” have been detected in space, but the real kicker is graphene. Its technical name is planar C24 and instead of being geodesic, it’s the thinnest substance known. Just one atom thick, this flat sheet of carbon is a portrait in extraordinary strength, conductivity and elasticity. Graphene was first synthesized in the lab in 2004 and now planar C24 may have been detected in space.

Through the use of the Spitzer Space Telescope, a team of astronomers led by Domingo Aníbal García-Hernández of the Instituto de Astrofísica de Canarias in Spain have not only picked up a C70 fullerene molecule, but may have also detected graphene as well. “If confirmed with laboratory spectroscopy – something that is almost impossible with the present techniques – this would be the first detection of graphene in space” said García-Hernández.

Letizia Stanghellini and Richard Shaw, members of the team at the National Optical Astronomy Observatory in Tucson, Arizona suspect collisional shocks generated in stellar winds of planetary nebulae could be responsible for the presence of fullerenes and graphenes through the destruction of hydrogenated amorphous carbon grains (HACs). “What is particularly surprising is that the existence of these molecules does not depend on the stellar temperature, but on the strength of the wind shocks” says Stanghellini.

So where has this discovery taken place? Try the Magellanic Clouds. In this case, using a planetary nebula “closer to home” is not part of the equation because science needs to be certain the material they are looking at is indeed the by-product of a planetary nebula and not a mix. Fortunately the SMG is known to be metal-poor, which enhances the chances of spotting complex carbon molecules. Right now the challenge has been to pinpoint the evidence for graphene from Spitzer data.

“The Spitzer Space Telescope has been amazingly important for studying complex organic molecules in stellar environments” says Stanghellini. “We are now at the stage of not only detecting fullerenes and other molecules, but starting to understand how they form and evolve in stars.” Shaw adds “We are planning ground-based follow up through the NOAO system of telescopes. We hope to find other molecules in planetary nebulae where fullerene has been detected to test some physical processes that might help us understand the biochemistry of life.”

Original News Source: National Optical Astronomy Observatory News Release.

August 6, 2011December 24, 2015 by Tammy Plotner

96 New Reasons To Love Star Clusters

Using data from the VISTA infrared survey telescope at ESO’s Paranal Observatory, an international team of astronomers has discovered 96 new open clusters hidden by the dust in the Milky Way. Thirty of these clusters are shown in this mosaic. The images are made using infrared light in the following bands: J (shown in blue), H (shown in green), and Ks (shown in red). Credit: ESO/J. Borissova

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“Ninety-six clusters of stars in the sky…. Ninety-six clusters of stars… You take one down and pass it around…” Do you need ninety-six new reasons to love astronomy? Then you’re going to want to hear about all the new discoveries the VISTA infrared survey telescope at ESO’s Paranal Observatory has made. Read on…

An international team of astronomers has taken observations to the next level with their discovery of 96 new star clusters which have been hidden behind the dusty cloak of interstellar matter. By utilizing sensitive infrared detectors and the world’s largest survey telescope, the intrepid crew set a new record for finding so many faint and small clusters at one time.

“This discovery highlights the potential of VISTA and the VVV survey for finding star clusters, especially those hiding in dusty star-forming regions in the Milky Way’s disc. VVV goes much deeper than other surveys,” says Jura Borissova, lead author of the study.

As astronomy enthusiasts well know, there’s more to a galactic cluster than just a pretty grouping of stars. Age, relation and motion all play a role. Some are loose groupings – held together by mutual gravitational attraction. Others are torn apart through interactions. Still others are in the process of formation, caught in the act with their gases showing. Yet all share a common denominator: they are around few hundred million years old and they are the by-product of a galaxy with active star formation.

“In order to trace the youngest star cluster formation we concentrated our search towards known star-forming areas. In regions that looked empty in previous visible-light surveys, the sensitive VISTA infrared detectors uncovered many new objects,” adds Dante Minniti, lead scientist of the VVV survey.

Once the grouping has been discovered, classification comes next. Through the use of specialized computer software, the team was able to separate foreground stars from genuine cluster components. Observation then came into play as stellar members were counted, sizes estimated, distances computed and extinction taken into consideration.

“We found that most of the clusters are very small and only have about 10–20 stars. Compared to typical open clusters, these are very faint and compact objects — the dust in front of these clusters makes them appear 10,000 to 100 million times fainter in visible light. It’s no wonder they were hidden,” explains Radostin Kurtev, another member of the team.

Since antiquity only 2500 open clusters have been found in the Milky Way, but astronomers estimate there might be as many as 30,000 still hiding behind the dust and gas. That means these new 96 open clusters could be only the very beginning of a host of new discoveries. “We’ve just started to use more sophisticated automatic software to search for less concentrated and older clusters. I am confident that many more are coming soon,” adds Borissova.

Until then we’ll just “Take one down and pass it around… 29,999 clusters of stars in the sky.”

Original Story Source: ESO Press Release.

July 22, 2011December 24, 2015 by Tammy Plotner

Caught In The Web… Space Spider!

IC 342's dust structures show up vividly in red, in this infrared view from Spitzer. Image credit: NASA/JPL-Caltech

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Look, he’s crawling up my wall… Black and hairy, very small… Now he’s up above my head… Hanging by a little thread. Nope. It’s not Boris the Spider, it’s spiral galaxy IC 342 and it’s hanging out in the constellation of Camelopardalis. Thanks to NASA’s Spitzer Space Telescope, we’re able to peer through the dust clouds and sneak a peek at this arachnid appearing beastie.

Residing at an approximate distance of 10 million light-years, this impressive grand design spiral is difficult for details because it’s located directly behind the disk of the Milky Way from our point of view. Tiny particles of interstellar dust, which measure just a fraction of a micron across, approximate the blue wavelength of light. These vast areas composed of silicates, carbon, ice, and/or iron compounds dim the light in a process called extinction – but using infrared vision can even the score. Line-of-sight stars from our galaxy appear blue/white and the blue haze around the galaxy’s nucleus is from IC 342’s collective starlight. Its gangly arms glow a soft crimson and clumps of newly forming stars radiate red.

It’s small wonder the core of IC 342 appears so spooky. According to research, it has undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way. Can you observe Boris yourself? Absolutely. You’ll find this magnitude 9 critter located along the galactic equator at RA 03h 46m 48.5s – Dec +68 05′ 46″. But beware… Its low surface brightness means you’ll need a rich field telescope and good, dark skies.

Creepy, crawly… Creepy, crawly… Creepy, creepy, crawly, crawly…

Original News Source: JPL / Spitzer News.

July 21, 2011December 24, 2015 by Tammy Plotner

Cosmic Crime Alert… LMC Is Swiping Stars!

The Milky Way’s near neighbor, the Large Magellanic Cloud (LMC), has accreted a smattering of stars from its smaller neighbor, the Small Magellanic Cloud (SMC). In this image, the LMC is shown as it appears in observations by the Spitzer Space Telescope at 3.6, 8.0, and 24 microns. Overlaid in red and blue, with colors representing the light of sight velocities (red = away, blue = towards) are the locations of stars whose origin has been traced to the SMC. These stars were discovered by a team led by NOAO astronomer Knut Olsen, through analysis of spectra obtained at the CTIO 4-m Blanco telescope. Spitzer image credit: Karl Gordon and Margaret Meixner (Space Telescope Science Institute/AURA/NASA). Compilation by K. Olsen (NOAO/AURA/NSF))

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Using the Spitzer Space Telescope, a team of astronomers from the National Optical Astronomy Observatory (NOAO) have made a unique discovery. Our neighbor – the Large Magellanic Cloud – has been caught pilfering stars from the Small Magellanic Cloud! What caused this cosmic crime and what do we know about it? Read on…

Through the use of spectra, 5900 giant and supergiant stars in the Large Magellanic Cloud have been identified as once belonging to the nearby Small Magellanic Cloud. NOAO astronomers Knut Olsen and Bob Blum, and their collaborators Dennis Zaritsky (University of Arizona), and Martha Boyer and Karl Gordon (Space Telescope Science Institute) were hot on the trail as they ascertained a counter rotation in a small percentage of the stellar population. Although they could only take information from “line of sight” stars, this 5% was enough to give them a clue they weren’t formed where they are now located. Even their chemical signature isn’t right!

“Further examination of these counter-rotating stars revealed another anomaly. The chemical composition of these stars is different. They have fewer heavy elements such as iron and calcium than typical stars in the Large Magellanic Cloud.” say the team. “However, their composition closely matches that of stars in another nearby galaxy, the Small Magellanic Cloud, whose stars are also depleted in these “metals”.

Just like fingerprints, these two signatures – motion and composition – are a dead giveaway that these certain stars have been lifted by gravitational interaction. To further refine the evidence the group used the multi-object spectrometer on the Cerro Tololo Inter-American Observatory 4-meter Blanco Telescope in Chile to observe 4600 stars, and their spectra, simultaneously. When compared to 1300 other stars, a pattern begin to emerge. According to Olsen “It is not always easy to tell whether the stars in a galaxy formed in the galaxy or formed somewhere else and then were captured. Since the LMC is so close to us, we were able to observe a large number of individual stars. And to our surprise, the LMC contained a significant number of stars that must have formed elsewhere.”

Continuing their investigations with the Spitzer Space Telescope, the team is also involved with stellar evolution studies in the LMC. NOAO Deputy Director Bob Blum indicated the importance of this approach: “Using observations with the Spitzer Space Telescope, we were able to get a complete census of the stellar populations in the LMC. With the ground-based observations we could determine the properties and motions of a large sample of stars throughout that galaxy. By combining both, we were able to tell that some of the stars must have come from the neighboring SMC. This led us to a deeper understanding of how galaxies can and do interact, and change over time.”

These studies may help us to further understand high rates of star formation in areas like 30 Doradus… When we’re not just stealin’ a look.

Original News Source: NOAO News.

June 25, 2011December 24, 2015 by Steve Nerlich

Astronomy Without A Telescope – Backgrounds

Thousands of galaxies observed by the Herschel Space Observatory through the Lockman hole. Credit: ESA.

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You’ve probably heard of the cosmic microwave background, but it doesn’t stop there. The as-yet-undetectable cosmic neutrino background is out there waiting to give us a view into the first seconds after the Big Bang. Then, looking further forward, there are other backgrounds across the electromagnetic spectrum – all of which contribute to what’s called the extragalactic background light, or EBL.

The EBL is the integrated whole of all light that has ever been radiated by all galaxies across all of time. At least, all of time since stars and galaxies first came into being – which was after the dark ages that followed the release of the cosmic microwave background.

The cosmic microwave background was released around 380,000 years after the Big Bang. The dark ages may have then persisted for another 750 million years, until the first stars and the first galaxies formed.

In the current era, the cosmic microwave background is estimated to make up about sixty percent of the photon density of all background radiation in the visible universe – the remaining forty per cent representing the EBL, that is the radiation contributed by all the stars and galaxies that have appeared since.

This gives some indication of the enormous burst of light that the cosmic microwave background represented, although it has since been red-shifted into almost invisibility over the subsequent 13.7 billion years. The EBL is dominated by optical and infrared backgrounds, the former being starlight and the latter being dust heated by that starlight which emits infrared radiation.

Just like the cosmic microwave background can tell us something about the evolution of the earlier universe, the cosmic infrared background can tell us something about the subsequent evolution of the universe – particularly about the formation of the first galaxies.

The power density of the universe's background radiation plotted over wavelength. The cosmic microwave background, though substantially red-shifted due to its age, still dominates. The remainder, extragalactic background light, is dominated by optical and infrared radiation, which have power densities several orders of magnitude higher than the remaining radiation wavelengths.

The Photodetector Array Camera and Spectrometer (PACS) Evolutionary Probe is a ‘guaranteed time’ project for the Herschel Space Observatory. Guaranteed means there always a certain amount of telescope time dedicated to this project regardless of other priorities. The PACS Evolutionary Probe project, or just PEP, aims to survey the cosmic infrared background in the relatively dust free regions of the sky that include: the Lockman Hole; the Great Observatories Origins Deep Survey (GOODS) fields; and the Cosmic Evolution Survey (COSMOS) field.

The Herschel PEP project is collecting data to enable determination of rest frame radiation of galaxies out to a redshift of about z =3, where you are observing galaxies when the universe was about 3 billion years old. Rest frame radiation means making an estimation of the nature of the radiation emitted by those early galaxies before their radiation was red-shifted by the intervening expansion of the universe.

The data indicate that infrared contributes around half of the total extragalactic background light. But if you just look at the current era of the local universe, infrared only contributes one third. This suggests that more infrared radiation was produced in the distant past, than in the present era.

This may be because earlier galaxies had more dust – while modern galaxies have less. For example, elliptical galaxies have almost no dust and radiate almost no infrared. However, luminous infrared galaxies (LIRGs) radiate strongly in infrared and less so in optical, presumably because they have a high dust content.

Modern era LIRGs may result from galactic mergers which provide a new supply of unbound dust to a galaxy, stimulating new star formation. Nonetheless, these may be roughly analogous to what galaxies in the early universe looked like.

Dustless, elliptical galaxies are probably the evolutionary end-point of an galactic merger, but in the absence of any new material to feed off these galaxies just contain aging stars.

So it seems that having a growing number of elliptical galaxies in your backyard is a sign that you live in a universe that is losing its fresh, infrared flush of youth.

Further reading: Berta et al Building the cosmic infrared background brick by brick with Herschel/PEP