Posted on by Nancy Atkinson

Light From a ‘SuperEarth’ Detected for the First Time

NASA's Spitzer Space Telescope was able to detect a super Earth's direct light for the first time using its sensitive heat-seeking infrared vision. Super Earth's are more massive than Earth but lighter than gas giants like Neptune. As this artist's concept shows, in visible light, a planet is lost in the glare of its star (top view). When viewed in infrared, the planet becomes brighter relative to its star. This is largely due to the fact that the planet's scorching heat blazes with infrared light. Even on our own bodies emanate more infrared light than visible due to our heat. Image credit: NASA/JPL-Caltech

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The star 55 Cancri has been a source of joy and firsts for planet hunters. Not only was it one of the first known stars to host an extrasolar planet, but now the light from one of its five known planets has been detected directly with the Spitzer Space Telescope, the first time a ‘smaller’ exoplanet’s light has been detected directly. Planet “e” is a super-Earth, about twice as big and eight times as massive as Earth. Scientists say that while the planet is not habitable, the detection is a historic step toward the eventual search for signs of life on other planets.

“Spitzer has amazed us yet again,” said Bill Danchi, Spitzer program scientist. “The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA’s upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets.”


The first planet around 55 Cancri was reported in 1997 and 55 Cancri e – the innermost planet in the system — was discovered via radial velocity measurements in 2004. This planet has been studied as much as possible, and astronomers were able to determine its mass and radius.

But now, Spitzer has measured how much infrared light comes from the planet itself. The results reveal the planet is likely dark, and its sun-facing side is more than 2,000 Kelvin (1,726 degrees Celsius, 3,140 degrees Fahrenheit), hot enough to melt metal.

In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system, when it saw the infrared light of a “hot Jupiter,” a gaseous planet much larger than 55 Cancri e. Since then, other telescopes, including NASA’s Hubble and Kepler space telescopes, have performed similar feats with gas giants using the same method.

In this method, a telescope gazes at a star as a planet circles behind it. When the planet disappears from view, the light from the star system dips ever so slightly, but enough that astronomers can determine how much light came from the planet itself. This information reveals the temperature of a planet, and, in some cases, its atmospheric components. Most other current planet-hunting methods obtain indirect measurements of a planet by observing its effects on the star.

The new information about 55 Cancri e, along with knowing it is about 8.57 Earth masses, the radius is 1.63 times that of Earth, and the density is 10.9 ± 3.1 g cm-3 (the average density of Earth is 5.515 g cm-3), places the planet firmly into the categories of a rocky super-Earth. But it could be surrounded by a layer of water in a “supercritical” state where it is both liquid and gas, and topped by a blanket of steam.

“It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away,” said Michaël Gillon of Université de Liège in Belgium, principal investigator of the research, which appears in the Astrophysical Journal. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.

The 55 Cancri system is relatively close to Earth, at 41 light-years away, and the star can be seen with the naked eye. 55 Cancri e is tidally locked, so one side always faces the star. Spitzer discovered the sun-facing side is extremely hot, indicating the planet probably does not have a substantial atmosphere to carry the sun’s heat to the unlit side.

NASA’s James Webb Space Telescope, scheduled to launch in 2018, likely will be able to learn even more about the planet’s composition. The telescope might be able to use a similar infrared method to Spitzer to search other potentially habitable planets for signs of molecules possibly related to life.

“When we conceived of Spitzer more than 40 years ago, exoplanets hadn’t even been discovered,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Because Spitzer was built very well, it’s been able to adapt to this new field and make historic advances such as this.”

During Spitzer’s ongoing extended mission, steps were taken to enhance its unique ability to see exoplanets, including 55 Cancri e. Those steps, which included changing the cycling of a heater and using an instrument in a new way, led to improvements in how precisely the telescope points at targets.

Source: JPL

Posted on by Nancy Atkinson

Top 10 Really Cool Infrared Images from Spitzer

The 'Tornado Nebula.' Credit: NASA / JPL-Caltech / J. Bally (University of Colorado)

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The Spitzer Space Telescope’s Infrared Array Camera (IRAC) is a cool camera, no matter what temperature in which it operates! For 1,000 days now, the camera has been continuously taking images of the Universe – from its most distant regions to our local solar neighborhood. The IRAC is now operating in a “warm” version of its mission, as after more than five-and-a-half years of probing the cool cosmos, in 2009 it ran out of liquid helium coolant that kept its infrared instruments chilled.

“IRAC continues to be an amazing camera, still producing important discoveries and spectacular new images of the infrared universe,” said principal investigator Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.

To commemorate 1,000 days of infrared wonders, the program is releasing a gallery of the 10 best IRAC images, featuring images from both the cold and warm portions of its mission. Above is #1: The IRAC has uncovered some mysterious objects like this so-called “tornado” nebula. Because the camera is sensitive to light emitted from shocked molecular hydrogen (seen here in green), astronomers think that this strange beast is the result of an outflowing jet of material from a young star that has generated shock waves in surrounding gas and dust.

See more below:

The Orion Nebula, as seen by Spitzer's IRAC. Credit: NASA / JPL-Caltech / Univ. of Toledo

#2. A ‘warm’ look at the famous nebula in Orion, located about 1,340 light-years from Earth, is actively making new stars today. Although the optical nebula is dominated by the light from four massive, hot young stars, IRAC reveals many other young stars still embedded in their dusty womb. It also finds a long filament of star-forming activity containing thousands of young protostars. Some of these stars may host still-forming planets.

The Helix Nebula. Credit: NASA / JPL-Caltech / J. Hora (CfA) & W. Latter (NASA/Herschel)

#3. After a long life of hydrogen-burning nuclear fusion, stars move into later life states whose details depend on their masses. This IRAC image of the Helix Nebula barely spots the star itself at the center, but clearly shows how the aging star has ejected material into space around it, creating a “planetary nebula.” The Helix Nebula is located 650 light-years away in the constellation Aquarius.

The Trifid Nebula. Credit: NASA / JPL-Caltech

#4. Located 5,400 light-years away in the constellation Sagittarius, the Trifid Nebula appears as a big maze of gas and dust. Here, Spitzer’s IRAC was observing how the processes of stellar evolution affects the surrounding environment. The Trifid Nebula hosts stars at all stages of life, and with images like this, scientists can observe how stars mature.

The 'Mountains of Creation' in the W5 region near Perseus. Credit: NASA / JPL-Caltech / CfA

#5. Within galaxies like the Milky Way, giant clouds of gas and dust coalesce under the influence of gravity until new stars are born. IRAC can both measure the warm dust and peer deeply into it to study the processes at work. In this giant cloud several stellar nurseries can be seen, some still within the tips of the dusty region that has been called the “Mountains of Creation, 7,000 light-years away from Earth.

DR22, in the constellation Cygnus the Swan. Credit: NASA / JPL-Caltech

#6. After blowing away its natal material, the young star cluster seen here emits winds and harsh ultraviolet light that sculpt the remnant cloud into fantastic shapes. Astronomers are not sure when that activity suppresses future star formation by disruption, and when it facilitates star formation through compression. The cluster, known as DR22, is in the constellation Cygnus the Swan.

Spitzer's composite of the entire Milky Way Galaxy. Credit: NASA / JPL-Caltech / E. Churchwell (Univ. of Wisconsin)

#7. IRAC has systematically imaged the entire Milky Way disk, assembling a composite photograph containing billions of pixels with infrared emission from everything in this relatively narrow plane. The image here shows five end-to-end strips spanning the center of our galaxy. This image covers only one-third of the whole galactic plane. Astronomers unveiled a 55-meter version of the image at the AAS meeting in June of 2008, and you can see the entire image on the GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) Image Viewer, which provides a great way to view and browse this image.

The Whirlpool Galaxy and its companion. Credit: NASA / JPL-Caltech / R. Kennicutt (Univ. of Arizona)

#8. Collisions play an important role in galaxy evolution. These two galaxies – the Whirlpool and its companion – are relatively nearby at a distance of just 23 million light-years from Earth. IRAC sees the main galaxy as very red due to warm dust – a sign of active star formation that probably was triggered by the collision.

The Sombrero Galaxy. Credit: NASA / JPL-Caltech / R. Kennicutt (Univ. of Arizona)

#9. Star formation helps shape a galaxy’s structure through shock waves, stellar winds, and ultraviolet radiation. In this image of the nearby Sombrero Galaxy, IRAC clearly sees a dramatic disk of warm dust (red) caused by star formation around the central bulge (blue). The Sombrero is located 28 million light-years away in the constellation Virgo.

A field of galaxies, seen by Spitzer's IRAC. Credit: NASA / JPL-Caltech / SWIRE Team

#10. And coming in at #10 is this lovely image showing many points of light. They aren’t stars but entire galaxies. A few, like the mini-tadpole at upper right, are only hundreds of millions of light-years away so their shapes can be discerned. The most distant galaxies are too far away and appear as dots. Their light is seen as it was over ten billion years ago, when the universe was young.

Will we see more from Spitzer? Certainly. NASA’s Senior Review Panel has recommended extending the Spitzer warm mission through 2015.

See larger versions of these images at the Harvard Smithsonian Center for Astrophysics website.

Posted on by Nancy Atkinson

Astronomers See Stars Changing Right Before Their Eyes in Orion Nebula

This new view of the Orion nebula highlights fledging stars hidden in the gas and clouds. Image credit: NASA/ESA/JPL-Caltech/IRAM

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A gorgeous new image from the tag team effort of the Herschel and Spitzer Space telescopes shows a rainbow of colors within the Orion nebula. The different colors reflect the different wavelengths of infrared light captured by the two space observatories, and by combining their observations, astronomers can get a more complete picture of star formation. And in fact, astronomers have spotted young stars in the Orion nebula changing right before their eyes, over a span of just a few weeks!

Astronomers with Herschel mapped this region of the sky once a week for six weeks in the late winter and spring of 2011. Notice the necklace of stars strung across the middle of the image? Over just that short amount of time, a discernible change in the stars took place as they appeared to be rapidly heating up and cooling down. The astronomers wondered if the stars were actually maturing from being star embryos, moving towards becoming full-fledged stars.

To monitor for activity in protostars, Herschel’s Photodetector Array Camera and Spectrometer stared in long infrared wavelengths of light, tracing cold dust particles, while Spitzer took a look at the warmer dust emitting shorter infrared wavelengths. In this data, astronomers noticed that several of the young stars varied in their brightness by more than 20 percent over just a few weeks.

As this twinkling comes from cool material emitting infrared light, the material must be far from the hot center of the young star, likely in the outer disk or surrounding gas envelope. At that distance, it should take years or centuries for material to spiral closer in to the growing starlet, rather than mere weeks.

The astronomers said a couple of scenarios could account for this short span. One possibility is that lumpy filaments of gas funnel from the outer to the central regions of the star, temporarily warming the object as the clumps hit its inner disk. Or, it could be that material occasionally piles up at the inner edge of the disk and casts a shadow on the outer disk.

“Herschel’s exquisite sensitivity opens up new possibilities for astronomers to study star formation, and we are very excited to have witnessed short-term variability in Orion protostars,” said Nicolas Billot, an astronomer at the Institut de Radioastronomie Millimétrique (IRAM) in Grenada, Spain who is preparing a paper on the findings along with his colleagues. “Follow-up observations with Herschel will help us identify the physical processes responsible for the variability.”

Source: NASA

Posted on by Nancy Atkinson

Solid Buckyballs in Space are Stacked Like ‘Oranges in a Crate’

NASA's Spitzer Space Telescope has detected the solid form of buckyballs in space for the first time. To form a solid particle, the buckyballs must stack together like oranges in a crate, as shown in this illustration. Image credit: NASA/JPL-Caltech

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From a JPL press release:

Astronomers using data from NASA’s Spitzer Space Telescope have, for the first time, discovered buckyballs in a solid form in space. Prior to this discovery, the microscopic carbon spheres had been found only in gas form in the cosmos. The new work, led by Prof. Nye Evans of Keele University, appears in a paper in the journal Monthly Notices of the Royal Astronomical Society.

Formally named buckminsterfullerene, buckyballs are named after their resemblance to the late architect Buckminster Fuller’s geodesic domes. They are made up of 60 carbon molecules arranged into a hollow sphere like a football. Their unusual structure makes them ideal candidates for electrical and chemical applications on Earth, including superconducting materials, medicines, water purification and armour.

In the latest discovery, scientists using Spitzer detected tiny specks of matter, or particles, consisting of stacked buckyballs. They found the particles around a pair of stars called “XX Ophiuchi,” 6,500 light-years from Earth, and detected enough to fill the equivalent in volume to 10,000 Mount Everests.

“These buckyballs are stacked together to form a solid, like oranges in a crate,” said Prof. Evans. “The particles we detected are miniscule, far smaller than the width of a hair, but each one would contain stacks of millions of buckyballs.”

Buckyballs were detected definitively in space for the first time by Spitzer in 2010. Spitzer later identified the molecules in a host of different cosmic environments. It even found them in staggering quantities, the equivalent in mass to 15 Earth moons, in a nearby galaxy called the Small Magellanic Cloud.

In all of those cases, the molecules were in the form of gas. The recent discovery of buckyballs particles means that large quantities of these molecules must be present in some stellar environments in order to link up and form solid particles. The research team was able to identify the solid form of buckyballs in the Spitzer data because they emit light in a unique way that differs from the gaseous form.

“This exciting result suggests that buckyballs are even more widespread in space than the earlier Spitzer results showed,” said Mike Werner, project scientist for Spitzer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “They may be an important form of carbon, an essential building block for life, throughout the cosmos.”

Buckyballs have been found on Earth in various forms. They form as a gas from burning candles and exist as solids in certain types of rock, such as the mineral shungite found in Russia, and fulgurite, a glassy rock from Colorado that forms when lightning strikes the ground. In a test tube, the solids take on the form of dark, brown “goo.”

“The window Spitzer provides into the infrared universe has revealed beautiful structure on a cosmic scale,” said Bill Danchi, Spitzer program scientist at NASA Headquarters in Washington. “In yet another surprise discovery from the mission, we’re lucky enough to see elegant structure at one of the smallest scales, teaching us about the internal architecture of existence.”

Read the team’s paper here.

More info at the Royal Astronomical Society

Posted on by Nancy Atkinson

A Star-Making Blob from the Cosmic Dawn

This image shows one of the most distant galaxies known, called GN-108036, dating back to 750 million years after the Big Bang that created our universe. Credit: NASA, ESA, JPL-Caltech, STScI, and the University of Tokyo

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Looking back in time with some of our best telescopes, astronomers have found one of the most distant and oldest galaxies. The big surprise about this blob-shaped galaxy, named GN-108036, is how exceptionally bright it is, even though its light has taken 12.9 billion years to reach us. This means that back in its heyday – which astronomers estimate at about 750 million years after the Big Bang — it was generating an exceptionally large amount of stars in the “cosmic dawn,” the early days of the Universe.

“The high rate of star formation found for GN-108036 implies that it was rapidly building up its mass some 750 million years after the Big Bang, when the Universe was only about five percent of its present age,” said Bahram Mobasher, from the University of California, Riverside. “This was therefore a likely ancestor of massive and evolved galaxies seen today.”


An international team of astronomers, led by Masami Ouchi of the University of Tokyo, Japan, first identified the remote galaxy after scanning a large patch of sky with the Subaru Telescope atop Mauna Kea in Hawaii. Its great distance was then confirmed with the W.M. Keck Observatory, also on Mauna Kea. Then, infrared observations from the Spitzer and Hubble space telescopes were crucial for measuring the galaxy’s star-formation activity.

“We checked our results on three different occasions over two years, and each time confirmed the previous measurement,” said Yoshiaki Ono, also from the of the University of Tokyo.

Astronomers were surprised to see such a large burst of star formation because the galaxy is so small and from such an early cosmic era. Back when galaxies were first forming, in the first few hundreds of millions of years after the Big Bang, they were much smaller than they are today, having yet to bulk up in mass.

The team says the galaxy’s star production rate is equivalent to about 100 suns per year. For reference, our Milky Way galaxy is about five times larger and 100 times more massive than GN-108036, but makes roughly 30 times fewer stars per year.

Astronomers refer to the object’s distance by a number called its “redshift,” which relates to how much its light has stretched to longer, redder wavelengths due to the expansion of the universe. Objects with larger redshifts are farther away and are seen further back in time. GN-108036 has a redshift of 7.2. Only a handful of galaxies have confirmed redshifts greater than 7, and only two of these have been reported to be more distant than GN-108036.

About 380,000 years after the Big Bang, a decrease in the temperature of the Universe caused hydrogen atoms to permeate the cosmos and form a thick fog that was opaque to ultraviolet light, creating what astronomers call the cosmic dark ages.

“It ended when gas clouds of neutral hydrogen collapsed to generate stars, forming the first galaxies, which probably radiated high-energy photons and reionized the Universe,” Mobasher said. “Vigorous galaxies like GN-108036 may well have contributed to the reionization process, which is responsible for the transparency of the Universe today.”

“The discovery is surprising because previous surveys had not found galaxies this bright so early in the history of the universe,” said Mark Dickinson of the National Optical Astronomy Observatory in Tucson, Ariz. “Perhaps those surveys were just too small to find galaxies like GN-108036. It may be a special, rare object that we just happened to catch during an extreme burst of star formation.”

Sources: Science Paper by: Y. Ono et al., Subaru , Spitzer Hubble

Posted on by Nancy Atkinson

Evidence of a Late Heavy Bombardment Occuring in Another Solar System

This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Evidence for this barrage comes from NASA's Spitzer Space Telescope, whose infrared detectors picked up indications that one or more comets was recently torn to shreds after colliding with a rocky body. Image credit: NASA/JPL-Caltech

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Planetary scientists have not been able to agree that a turbulent period in our solar system’s history called the Late Heavy Bombardment actually occurred. But now, using observations from the Spitzer Space Telescope, scientists have detected activity resembling a similar type of event where icy bodies from the outer solar system are possibly pummeling rocky worlds closer to the star. This is the first time such activity has been seen in another planetary system.

“Where the comets are hitting the rocky bodies is in the habitable zone around this star, so not only are life-forming materials possibly being delivered to rocky worlds, but also in the right place for life as we know it to grow,” said Carey Lisse, senior research scientist at the Johns Hopkins University Applied Physics Laboratory. “This is similar to what happened to our own solar system during the Late Heavy Bombardment.”

Lisse spoke to journalists in a conference call from the Signposts of Planets meeting taking place at Goddard Space Flight Center this week.

Spitzer observations showed a band of dust around the nearby, naked-eye-visible star called Eta Corvi, located in the constellation Corvus in northern sky. Within the band of warm dust, Spitzer’s infrared detectors saw the chemical fingerprints of water ice, organics and rock, which strongly matches the contents of an obliterated giant comet, suggesting a collision took place between a planet and one or more comets. Also detected was evidence for flash-frozen rocks, nanodiamonds and amorphous silica.

This dust is located 3 AU away from Eta Corvi, which is the “habitable zone” around that star, and is close enough to the star that Earth-like worlds could exist. Lisse said although it hasn’t been confirmed, researchers think there is a Neptune-like world and at least two other planets in this system. A bright, icy Kuiper Belt-like region located 3-4 times farther out than our own Kuiper Belt was discovered around Eta Corvi in 2005.

“This is very possibly a planet-rich system,” Lisse said.

The light signature emitted by the dust around Eta Corvi also resembles meteorites found on Earth. “We see a match between dust around Eta Corvi and the Almahata Sitta meteorites, which fell to Earth in Sudan in 2008,” Llisse said. “We can argue that the material around Eta Covi is rich in carbon and water, things that help life grow on Earth.”

The Eta Corvi system is approximately one billion years old, which the research team considers about the right age for such a bombardment.

No asteroidal dust was found in the disk around Eta Corvi.

“Asteroidal dust would look like it had been heated, and chemically and physically altered, and most of the water and carbon would be gone,” Lisse said. “This dust is very rich in water and carbon and the rocky components are very primitive and un-altered.”

Most planetary formation theories can’t account for such an intense period of bombardment in our own solar system so late in its history, but the Nice Model proposed in 2005 suggests the Late Heavy Bombardment was triggered when the giant planets in our solar system— which formed in a more compact configuration – rapidly migrated away from each other (and their orbital separations all increased), and a disk of small asteroids and comets that lay outside the orbits of the planets was destabilized, causing a sudden massive delivery of asteroids and comets to the inner solar system. The barrage scarred the Moon and produced large amounts of dust.

“We can see the process of this happening at Eta Corvi and can learn more about our own solar system, since we can’t go back in time,” Lisse said. “It’s very possible that the rain of comets and Kuiper Belt Objects brought life to Earth.”

Lisse and his team are not sure if one big comet or lots of smaller comets are pummeling the inner solar system. “It is probably many bodies, but we only see the effects of the largest ones,” he said.

Could this be an indication that a Late Heavy Bombardment happens in many solar systems? “It’s not clear whether this is an atypical system, but we do know of one other possible system where it could be happening,” Lisse said in response to the question posed by Universe Today. “I think this is a rare event, which might mean that life is rare if you need a Late Heavy Bombardment for life to happen.”

Lisse said the reason they studied this star was the earlier detection of the Kuiper Belt-like region around Eta Corvi. “We knew it was an exceptional system from previous infrared sky surveys and the large bright Kuiper Belt was just the tip of the iceberg,” Lisse said. “This system was shouting, ‘I’m something extraordinary, come figure out my mystery!”

Paper: Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in Eta Corvi at ~1 Gyr

Source: Signposts of Planets conference call, JPL Press release

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 Nancy Atkinson

Spitzer’s Stunning New View of the North American Nebula

This swirling landscape of stars is known as the North American nebula. In visible light, the region resembles North America, but in this new infrared view from NASA's Spitzer Space Telescope, the continent disappears. Image credit: NASA/JPL-Caltech

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In visible light, the North American nebula resembles its namesake continent. But looking at it in the infrared spectrum, a whole new perspective explodes into view. Clouds of dust and gas come to life, as light from massive young star heats and shape the clouds, and dramatic clusters of baby stars which can only be seen in infrared burst into view.

“One of the things that makes me so excited about this image is how different it is from the visible image, and how much more we can see in the infrared than in the visible,” said Luisa Rebull of NASA’s Spitzer Science Center at the California Institute of Technology, Pasadena, Calif. Rebull is lead author of a paper about the observations, accepted for publication in the Astrophysical Journal Supplement Series. “The Spitzer image reveals a wealth of detail about the dust and the young stars here.”

Rebull and her team have identified more than 2,000 new, candidate young stars in the region. There were only about 200 known before. Because young stars grow up surrounded by blankets of dust, they are hidden in visible-light images. Spitzer’s infrared detectors pick up the glow of the dusty, buried stars.

This new view of the North American nebula combines both visible and infrared light observations, taken by the Digitized Sky Survey and NASA's Spitzer Space Telescope, respectively, into a single vivid picture. Image credit: NASA/JPL-Caltech

Combing infrared data with light from other parts of the spectrum gives astronomers a complete picture of star formation. Each different combination of observations gives insights into star formation.

But in Spitzer’s infrared view, the continent disappears. Instead, a swirling landscape of dust and young stars comes into view.

In this image, astronomers can see stars at all stages of life, from the early years when it is swaddled in dust to early adulthood, when it has become a young parent to a family of developing planets. Sprightly “toddler” stars with jets can also be identified in Spitzer’s view.

“This is a really busy area to image, with stars everywhere, from the North American complex itself, as well as in front of and behind the region,” said Rebull. “We refer to the stars that are not associated with the region as contamination. With Spitzer, we can easily sort this contamination out and clearly distinguish between the young stars in the complex and the older ones that are unrelated.”

There are a couple of mysteries about the North American Nebula still to be solved: astronomers think there must be more stars in the “Gulf of Mexico” region that must dominate the nebula and provide the main source of “power.” There is a dark tangle of clouds there that even Spitzers powerful infrared eyes can’t penetrate, but some light appears to be coming from behind that region, in the same way that sunlight creeps out from behind a rain cloud.

The nebula’s distance from Earth is also a mystery. Current estimates put it at about 1,800 light-years from Earth. Spitzer will refine this number by finding more stellar members of the North American complex.

See more info on the JPL website, where you can download full resolution versions of the images seen here, and more views of the North American nebula.

Posted on by Nicholos Wethington

The Strange Warm Spot of upsilon Andromedae b

The warmest part of upsilon Andromedae b is not directly under the light coming from its host star, as would be expected. Image Credit: NASA/JPL-Caltech

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If you set a big black rock outside in the Sun for a few hours, then go and touch it, you’d expect the warmest part of the rock to be that which was facing the Sun, right? Well, when it comes to exoplanets, your expectations will be defied. A new analysis of a well-studied exoplanetary system reveals that one of the planets – which is not a big black rock, but a Jupiter-like ball of gas – has its warmest part opposite that of its star.

The system of Upsilon Andromedae, which lies 44 light years away from the Earth in the constellation Andromeda, is a much studied system of planets that orbit around a star a little more massive and slightly hotter than our Sun.

The closest planet to the star, upsilon Andromeda b, was the first exoplanet to have its temperature taken by The Spitzer Space Telescope. As we reported back in 2006, upsilon Andromeda b was thought to be tidally locked to the star and show corresponding temperature changes at it went around its host star. That is, as it went behind the star from our perspective, the face was warmer than when it was in front of the star from our perspective. Simple enough, right? These original results were published in a paper in Science on October 27th, 2006, available here.

As it turns out, this temperature change scenario is not the case. UCLA Professor of Physics and Astronomy Brad Hansen, who is a co-author on both the 2006 paper and updated results, explains, “The original report was based on just a few hours of data, taken early in the mission, to see whether such a measurement was even possible (it is close to the limit of the expected performance of the instrument). Since the observations suggested it was possible to detect, we were awarded a larger amount of time to do it in more detail.”

Observations of upsilon Andromedae b were taken with the Spitzer again in February of 2009. Once the astronomers were able to study the planet more, they discovered something odd – just how warm the planet was when it passed in front of the star from our perspective was a lot warmer than when it passed behind, just the opposite of what one would expect, and opposite of the results they originally published. Here’s a link to an animation that helps explain this strange feature of the planet.

What the astronomers discovered – and have yet to explain fully – is that there is a “warm spot” about 80 degrees opposite of the face of the planet that is pointed towards the star. In other words, the warmest spot on the planet is not on the side of the planet that is receiving the most radiation from the star.

This in itself is not a novelty. Hansen said, “There are several exoplanets observed with warm spots, including some whose spots are shifted relative to the location facing the star (an example is the very well studied system HD189733b). The principal difference in this case is that the shift we observe is the largest known.”

Upsilon Andromedae b does not transit in front of its star from our vantage point on the Earth. Its orbit is inclined by about 30 degrees, so it appears to be passing “below” the star as it comes around the front. This means that astronomers cannot use the transit method of exoplanetary study to get a handle on its orbit, but rather measure the tug that the planet exerts on the star. It has been determined that upsilon Andromedae b orbits about every 4.6 days, has a mass 0.69 that of Jupiter and is about 1.3 Jupiter radii in diameter. To get a better idea of the whole system of upsilon Andromedae, see this story we ran earlier this year.

So what, exactly, could be causing this bizarrely placed warm spot on the planet? The paper authors suggest that equatorial winds – much like those on Jupiter – could be transferring heat around the planet.

A graph and visual representation of the hot spot as the planet orbits the star upsilon Andromedae. Image credit: NASA/JPL-Caltech/UCLA

Hansen explained, “At the sub-stellar point (the one closest to the star) the amount of radiation being absorbed from the star is highest, so the gas there is heated more. It will therefore have a tendency to flow away from the hot region towards cold regions. This, combined with rotation will give a “trade wind”-like structure to the gas flow on the planet… The big uncertainty is how that energy is eventually dissipated. The fact that we observe a hot spot at roughly 90 degrees suggests that this occurs somewhere near the “terminator” (the day/night edge). Somehow the winds are flowing around from the sub-stellar point and then dissipating as they approach the night side. We speculate that this may be from the formation of some kind of shock front.”

Hansen said that they are unsure just how large this warm spot is. “We have only a very crude measure of this, so we have modeled as basically two hemispheres – one hotter than the other. One could make the spot smaller and make it correspondingly hotter and you would get the same effect. So, one can trade off spot size versus temperature contrast while still matching the observations.”

The most recent paper, which is co-authored by members from the United States and the UK, will appear in the Astrophysical Journal. If you’d like to go outside and see the star upsilon Andromedae,here’s a star chart.

Source: JPL Press Release, Arxiv here and here , email interview with Professor Brad Hansen.