Chandra, Spitzer Study Suggests Black Holes Abundant Among The Earliest Stars

By comparing infrared and X-ray background signals across the same stretch of sky, an international team of astronomers has discovered evidence of a significant number of black holes that accompanied the first stars in the universe.

Using data from NASA’s Chandra X-ray Observatory and NASA’s Spitzer Space Telescope, which observes in the infrared, researchers have concluded one of every five sources contributing to the infrared signal is a black hole.

The cosmic microwave background, shown at left in this illustration, is a flash of light that occurred when the young universe cooled enough for electrons and protons to form the first atoms. It contains slight temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all cosmic structure we see around us today. The universe then went dark for hundreds of millions of years until the first stars shone and the first black holes began accreting gas. A portion of the infrared and X-ray signals from these sources is preserved in the cosmic infrared background, or CIB, and its X-ray equivalent, the CXB. At least 20 percent of the structure in these backgrounds changes in concert, indicating that black hole activity was hundreds of times more intense in the early universe than it is today.

The cosmic microwave background, shown at left in this illustration, is a flash of light that occurred when the young universe cooled enough for electrons and protons to form the first atoms. It contains slight temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all cosmic structure we see around us today. The universe then went dark for hundreds of millions of years until the first stars shone and the first black holes began accreting gas. A portion of the infrared and X-ray signals from these sources is preserved in the cosmic infrared background, or CIB, and its X-ray equivalent, the CXB. At least 20 percent of the structure in these backgrounds changes in concert, indicating that black hole activity was hundreds of times more intense in the early universe than it is today.

“Our results indicate black holes are responsible for at least 20 percent of the cosmic infrared background, which indicates intense activity from black holes feeding on gas during the epoch of the first stars,” said Alexander Kashlinsky, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md.

The cosmic infrared background (CIB) is the collective light from an epoch when structure first emerged in the universe. Astronomers think it arose from clusters of massive suns in the universe’s first stellar generations, as well as black holes, which produce vast amounts of energy as they accumulate gas.

Even the most powerful telescopes cannot see the most distant stars and black holes as individual sources. But their combined glow, traveling across billions of light-years, allows astronomers to begin deciphering the relative contributions of the first generation of stars and black holes in the young cosmos. This was at a time when dwarf galaxies assembled, merged and grew into majestic objects like our own Milky Way galaxy.

“We wanted to understand the nature of the sources in this era in more detail, so I suggested examining Chandra data to explore the possibility of X-ray emission associated with the lumpy glow of the CIB,” said Guenther Hasinger, director of the Institute for Astronomy at the University of Hawaii in Honolulu, and a member of the study team.
Read more at http://www.nasa.gov/topics/universe/features/abundant-black-holes.html

Spitzer Finds Possible Exoplanet Smaller Than Earth

Astronomers using NASA’s Spitzer Space Telescope have detected what they believe is an alien world just two-thirds the size of Earth – one of the smallest on record. The exoplanet candidate, known as UCF-1.01, orbits a star called GJ 436, which is located a mere 33 light-years away. UCF-1.01 might be the nearest world to our solar system that is smaller than our home planet. Credit: NASA/JPL-Caltech

Astronomers using NASA’s Spitzer Space Telescope have detected what they believe is a planet two-thirds the size of Earth. The exoplanet candidate, called UCF-1.01, is located a mere 33 light-years away, making it possibly the nearest world to our solar system that is smaller than our home planet.

Exoplanets circle stars beyond our sun. Only a handful smaller than Earth have been found so far. Spitzer has performed transit studies on known exoplanets, but UCF-1.01 is the first ever identified with the space telescope, pointing to a possible role for Spitzer in helping discover potentially habitable, terrestrial-sized worlds.

“We have found strong evidence for a very small, very hot and very near planet with the help of the Spitzer Space Telescope,” said Kevin Stevenson from the University of Central Florida in Orlando. Stevenson is lead author of the paper, which has been accepted for publication in The Astrophysical Journal. “Identifying nearby small planets such as UCF-1.01 may one day lead to their characterization using future instruments.”

The hot, new-planet candidate was found unexpectedly in Spitzer observations. Stevenson and his colleagues were studying the Neptune-sized exoplanet GJ 436b, already known to exist around the red-dwarf star GJ 436. In the Spitzer data, the astronomers noticed slight dips in the amount of infrared light streaming from the star, separate from the dips caused by GJ 436b. A review of Spitzer archival data showed the dips were periodic, suggesting a second planet might be orbiting the star and blocking out a small fraction of the star’s light.

This technique, used by a number of observatories including NASA’s Kepler space telescope, relies on transits to detect exoplanets. The duration of a transit and the small decrease in the amount of light registered reveals basic properties of an exoplanet, such as its size and distance from its star. In UCF-1.01’s case, its diameter would be approximately 5,200 miles (8,400 kilometers), or two-thirds that of Earth. UCF-1.01 would revolve quite tightly around GJ 436, at about seven times the distance of Earth from the moon, with its “year” lasting only 1.4 Earth days. Given this proximity to its star, far closer than the planet Mercury is to our sun, the exoplanet’s surface temperature would be more than 1,000 degrees Fahrenheit (almost 600 degrees Celsius).

If the roasted, diminutive planet candidate ever had an atmosphere, it almost surely has evaporated. UCF-1.01 might therefore resemble a cratered, mostly geologically dead world like Mercury. Paper co-author Joseph Harrington, also of the University of Central Florida and principal investigator of the research, suggested another possibility; that the extreme heat of orbiting so close to GJ 436 has melted the exoplanet’s surface.

“The planet could even be covered in magma,” Harrington said.

In addition to UCF-1.01, Stevenson and his colleagues noticed hints of a third planet, dubbed UCF-1.02, orbiting GJ 436. Spitzer has observed evidence of the two new planets several times each. However, even the most sensitive instruments are unable to measure exoplanet masses as small as UCF-1.01 and UCF-1.02, which are perhaps only one-third the mass of Earth. Knowing the mass is required for confirming a discovery, so the paper authors are cautiously calling both bodies exoplanet candidates for now.

Of the approximately 1,800 stars identified by NASA’ Kepler space telescope as candidates for having planetary systems, just three are verified to contain sub-Earth-sized exoplanets. Of these, only one exoplanet is thought to be smaller than the Spitzer candidates, with a radius similar to Mars, or 57 percent that of Earth.

“I hope future observations will confirm these exciting results, which show Spitzer may be able to discover exoplanets as small as Mars,” said Michael Werner, Spitzer project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Even after almost nine years in space, Spitzer’s observations continue to take us in new and important scientific directions.”
Read more: www.nasa.gov

NASA’s Spitzer Sees the Light of Alien ‘Super Earth’

Seen here in this artist’s concept, the planet is called 55 Cancri e. It’s a toasty world that rushes around its star every 18 hours. Image credit: NASA/JPL-Caltech

NASA’s Spitzer Space Telescope has detected light emanating from a “super-Earth” planet beyond our solar system for the first time. 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 at NASA Headquarters in Washington. “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.”

This artist’s animation depicts 55 Cancri e as it orbits its star. The planet whips around the star closely and quickly: It is 25 times closer to the star than Mercury is to our sun and completes one orbit — its year — in a mere 18 hours.

http://youtu.be/8l9SPAmtHJ8

The planet, called 55 Cancri e, falls into a class of planets termed super Earths, which are more massive than our home world but lighter than giant planets like Neptune. The planet is about twice as big and eight times as massive as Earth. It orbits a bright star, called 55 Cancri, in a mere 18 hours.

Previously, Spitzer and other telescopes were able to study the planet by analyzing how the light from 55 Cancri changed as the planet passed in front of the star. In the new study, Spitzer 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 (3,140 degrees Fahrenheit), hot enough to melt metal.

The new information is consistent with a prior theory that 55 Cancri e is a water world: a rocky core 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 plot shows how the infrared light from the 55 Cancri system, both the star and planet, changed as the planet passed behind its star in what is called an occultation. When the planet disappeared, the total light dropped, and then increased back to normal levels as the planet circled back into view. The drop indicated how much light came directly from the planet itself. This type of information is important for studying the temperatures and compositions of planetary atmospheres beyond our own

The 55 Cancri system is relatively close to Earth, at 41 light-years away. It has five planets, with 55 Cancri e the closest to the star and 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.”

In 2005, Spitzer became the first telescope to detect light from a planet beyond our solar system. To the surprise of many, the observatory saw the infrared light of a “hot Jupiter,” a gaseous planet much larger than the solid 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….
Read more: www.nasa.gov

NASA Telescopes Help Solve Ancient Supernova Mystery

This image combines data from four different space telescopes to create a multi-wavelength view of all that remains of the oldest documented example of a supernova, called RCW 86

A mystery that began nearly 2,000 years ago, when Chinese astronomers witnessed what would turn out to be an exploding star in the sky, has been solved. New infrared observations from NASA’s Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE, reveal how the first supernova ever recorded occurred and how its shattered remains ultimately spread out to great distances.

The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.

“This supernova remnant got really big, really fast,” said Brian J. Williams, an astronomer at North Carolina State University in Raleigh. Williams is lead author of a new study detailing the findings online in the Astrophysical Journal. “It’s two to three times bigger than we would expect for a supernova that was witnessed exploding nearly 2,000 years ago. Now, we’ve been able to finally pinpoint the cause.”

A new image of the supernova, known as RCW 86, is online athttp://go.nasa.gov/pnv6Oy .

In 185 A.D., Chinese astronomers noted a “guest star” that mysteriously appeared in the sky and stayed for about 8 months. By the 1960s, scientists had determined that the mysterious object was the first documented supernova. Later, they pinpointed RCW 86 as a supernova remnant located about 8,000 light-years away. But a puzzle persisted. The star’s spherical remains are larger than expected. If they could be seen in the sky today in infrared light, they’d take up more space than our full moon.

The solution arrived through new infrared observations made with Spitzer and WISE, and previous data from NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM-Newton Observatory.

The findings reveal that the event is a “Type Ia” supernova, created by the relatively peaceful death of a star like our sun, which then shrank into a dense star called a white dwarf. The white dwarf is thought to have later blown up in a supernova after siphoning matter, or fuel, from a nearby star.

“A white dwarf is like a smoking cinder from a burnt-out fire,” Williams said. “If you pour gasoline on it, it will explode.”

The observations also show for the first time that a white dwarf can create a cavity around it before blowing up in a Type Ia event. A cavity would explain why the remains of RCW 86 are so big. When the explosion occurred, the ejected material would have traveled unimpeded by gas and dust and spread out quickly.

Spitzer and WISE allowed the team to measure the temperature of the dust making up the RCW 86 remnant at about minus 325 degrees Fahrenheit, or minus 200 degrees Celsius. They then calculated how much gas must be present within the remnant to heat the dust to those temperatures. The results point to a low-density environment for much of the life of the remnant, essentially a cavity.

Scientists initially suspected that RCW 86 was the result of a core-collapse supernova, the most powerful type of stellar blast. They had seen hints of a cavity around the remnant, and, at that time, such cavities were only associated with core-collapse supernovae. In those events, massive stars blow material away from them before they blow up, carving out holes around them.

But other evidence argued against a core-collapse supernova. X-ray data from Chandra and XMM-Newton indicated that the object consisted of high amounts of iron, a telltale sign of a Type Ia blast. Together with the infrared observations, a picture of a Type Ia explosion into a cavity emerged.

“Modern astronomers unveiled one secret of a two-millennia-old cosmic mystery only to reveal another,” said Bill Danchi, Spitzer and WISE program scientist at NASA Headquarters in Washington. “Now, with multiple observatories extending our senses in space, we can fully appreciate the remarkable physics behind this star’s death throes, yet still be as in awe of the cosmos as the ancient astronomers.”

NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer.
http://www.nasa.gov

It’s Raining Comets

NASA’s Spitzer Detects Comet Storm In Nearby 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. In this artist’s conception, one such giant comet is shown smashing into a rocky planet, flinging ice- and carbon-rich dust into space, while also smashing water and organics into the surface of the planet. A glowing red flash captures the moment of impact on the planet. Yellow-white Eta Corvi is shown to the left, with still more comets streaming toward it.
Spitzer detected spectral signatures of water ice, organics and rock around Eta Corvi — key ingredients of comets. This is the first time that evidence for such a comet storm has been seen around another star. Eta Corvi is just about the right age, about one billion years old, to be experiencing a bombardment of comets akin to what occurred in our own solar system at 600 to 800 millions years of age, termed the Late Heavy Bombardment.
Scientists say the Late Heavy Bombardment was triggered in our solar system by the migration of our outer planets, which jostled icy comets about, sending some of them flying inward. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life.

NASA’s Spitzer Detects Comet Storm In Nearby Solar System

NASA’s Spitzer Space Telescope has detected signs of icy bodies raining down in an alien solar system. The downpour resembles our own solar system several billion years ago during a period known as the “Late Heavy Bombardment,” which may have brought water and other life-forming ingredients to Earth.

During this epoch, comets and other frosty objects that were flung from the outer solar system pummeled the inner planets. The barrage scarred our moon and produced large amounts of dust.

Now Spitzer has spotted a band of dust around a nearby bright star in the northern sky called Eta Corvi that strongly matches the contents of an obliterated giant comet. This dust is located close enough to Eta Corvi that Earth-like worlds could exist, suggesting a collision took place between a planet and one or more comets. The Eta Corvi system is approximately one billion years old, which researchers think is about the right age for such a hailstorm.

“We believe we have direct evidence for an ongoing Late Heavy Bombardment in the nearby star system Eta Corvi, occurring about the same time as in our solar system,” said Carey Lisse, senior research scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., and lead author of a paper detailing the findings. The findings will be published in the Astrophysical Journal. Lisse presented the results at the Signposts of Planets meeting at NASA’s Goddard Space Flight Center in Greenbelt, Md., today, Oct. 19.

Astronomers used Spitzer’s infrared detectors to analyze the light coming from the dust around Eta Corvi. Certain chemical fingerprints were observed, including water ice, organics and rock, which indicate a giant comet source.

The light signature emitted by the dust around Eta Corvi also resembles the Almahata Sitta meteorite, which fell to Earth in fragments across Sudan in 2008. The similarities between the meteorite and the object obliterated in Eta Corvi imply a common birthplace in their respective solar systems.

A second, more massive ring of colder dust located at the far edge of the Eta Corvi system seems like the proper environment for a reservoir of cometary bodies. This bright ring, discovered in 2005, looms at about 150 times the distance from Eta Corvi as the Earth is from the sun. Our solar system has a similar region, known as the Kuiper Belt, where icy and rocky leftovers from planet formation linger. The new Spitzer data suggest that the Almahata Sitta meteorite may have originated in our own Kuiper Belt.

The Kuiper Belt was home to a vastly greater number of these frozen bodies, collectively dubbed Kuiper Belt objects. About 4 billion years ago, some 600 million years after our solar system formed, scientists think the Kuiper Belt was disturbed by a migration of the gas-giant planets Jupiter and Saturn. This jarring shift in the solar system’s gravitational balance scattered the icy bodies in the Kuiper Belt, flinging the vast majority into interstellar space and producing cold dust in the belt. Some Kuiper Belt objects, however, were set on paths that crossed the orbits of the inner planets.

The resulting bombardment of comets lasted until 3.8 billion years ago. After comets impacted the side of the moon that faces Earth, magma seeped out of the lunar crust, eventually cooling into dark “seas,” or maria. When viewed against the lighter surrounding areas of the lunar surface, those seas form the distinctive “Man in the Moon” visage. Comets also struck Earth or incinerated in the atmosphere, and are thought to have deposited water and carbon on our planet. This period of impacts might have helped life form by delivering its crucial ingredients.

“We think the Eta Corvi system should be studied in detail to learn more about the rain of impacting comets and other objects that may have started life on our own planet,” Lisse said.
http://www.nasa.gov

Spitzer Detects a Steaming Super-Earth Eclipsing Its Star

NASA’s Spitzer Space Telescope has gathered surprising new details about a supersized and superheated version of Earth called 55 Cancri e. According to Spitzer data, the exoplanet is less dense than previously thought, a finding which profoundly changes the portrait of this exotic world. Instead of a dense rock scorched dry by its sun, 55 Cancri e likely has water vapor and other gases steaming from its molten surface.

Spitzer measured the extraordinarily small amount of light 55 Cancri e blocked when the planet crossed in front of its star. These mini-eclipses, called transits, allow astronomers to accurately determine a planet’s size and calculate its density. Promisingly, the results show how astronomers can use Spitzer, operating in “warm” mode since depleting its liquid coolant in May 2009, to probe the properties of strange alien worlds….. Continue reading Spitzer Detects a Steaming Super-Earth Eclipsing Its Star

NASA’s Spitzer Finds Distant Galaxies Grazed on Gas

Galaxies Near and Far

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). NASA's Spitzer Space Telescope discovered that distant populations of galaxies formed massive, bright stars more commonly than today's "diet-conscious" galaxies. Such early galaxies would have been brighter, bluer and more irregular than spiral galaxies today due to the large proportion of massive stars. The Spitzer observations also demonstrate that these distant galaxies fed off steady streams of gas, rather than bursts of gas stirred up from collisions with other galaxies. This artist's rendering is derived from the Hubble image of NGC 1309

Galaxies once thought of as voracious tigers are more like grazing cows, according to a new study using NASA’s Spitzer Space Telescope.
Astronomers have discovered that galaxies in the distant, early universe continuously ingested their star-making fuel over long periods of time. This goes against previous theories that the galaxies devoured their fuel in quick bursts after run-ins with other galaxies.
“Our study shows the merging of massive galaxies was not the dominant method of galaxy growth in the distant universe,” said Ranga-Ram Chary of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena, Calif. “We’re finding this type of galactic cannibalism was rare. 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.”….. Continue reading NASA’s Spitzer Finds Distant Galaxies Grazed on Gas