Saturday, August 2, 2014

Giant Ultraviolet Rings Found in Resurrected Galaxies

Giant Ultraviolet Rings Found in Resurrected Galaxies:

Rings and arcs of ultraviolet light around a selection of galaxies imaged by Hubble
Astronomers have found unexpected rings and arcs of ultraviolet light around a selection of galaxies, four of which are shown here as viewed by NASA's and the European Space Agency's Hubble Space Telescope. Image credit: NASA/ESA /JPL-Caltech/STScI/UCLA


› Full image and caption


August 11, 2010

Astronomers have found mysterious, giant loops of ultraviolet light in aged, massive galaxies, which seem to have a second lease on life. Somehow these "over-the-hill galaxies" have been infused with fresh gas to form new stars that power these truly gargantuan rings, some of which could encircle several Milky Way galaxies.


The discovery of these rings implies that bloated galaxies presumed "dead" and devoid of star-making can be reignited with star birth, and that galaxy evolution does not proceed straight from the cradle to the grave.


"In a galaxy's lifetime, it must make the transition from an active, star-forming galaxy to a quiescent galaxy that does not form stars," said Samir Salim, lead author of a recent study and a research scientist in the department of astronomy at Indiana University, Bloomington. "But it is possible this process goes the other way, too, and that old galaxies can be rejuvenated."


A One-Two Observational Punch


The findings come courtesy of the combined power of two orbiting observatories, NASA's Galaxy Evolution Explorer and Hubble Space Telescope. First, the Galaxy Evolution Explorer surveyed a vast region of the sky in ultraviolet light. The satellite picked out 30 elliptical and lens-shaped "early" galaxies with puzzlingly strong ultraviolet emissions but no signs of visible star formation. Early-type galaxies, so the scientists' thinking goes, have already made their stars and now lack the cold gas necessary to build new ones.


The Galaxy Evolution Explorer could not discern the fine details of these large, rounded galaxies gleaming in the ultraviolet, so to get a closer look, researchers turned to the Hubble Space Telescope. What they saw shocked them: three-quarters of the galaxies were spanned by great, shining rings of ultraviolet light, with some ripples stretching 250,000 light-years. A few galaxies even had spiral-shaped ultraviolet features.


"We haven't seen anything quite like these rings before," said Michael Rich, co-author of the paper and a research astronomer at UCLA. "These beautiful and very unusual objects might be telling us something very important about the evolution of galaxies."


Colors of the Ages


Astronomers can tell a galaxy's approximate age just by the color of its collective starlight. Lively, young galaxies look bluish to our eyes due to the energetic starlight of their new, massive stars. Elderly galaxies instead glow in the reddish hues of their ancient stars, appearing "old, red and dead," as astronomers bluntly say. Gauging by the redness of their constituent stars, the galaxies seen by the Galaxy Evolution Explorer and Hubble are geezers, with most stars around 10 billion years old.


But relying on the spectrum of light visible to the human eye can be deceiving, as some of us have found out after spending a day under the sun's invisible ultraviolet rays and getting a sunburn. Sure enough, when viewed in the ultraviolet part of the spectrum, these galaxies clearly have more going on than meets the eye.


Some ultraviolet starlight in a few of the observed galaxies might just be left over from an initial burst of star formation. But in most cases, new episodes of star birth must be behind the resplendent rings, meaning that fresh gas has somehow been introduced to these apparently ancient galaxies. Other telltale signs of ongoing star formation, such as blazing hydrogen gas clouds, might be on the scene as well, but have so far escaped detection.


The Lord of the Ultraviolet Rings


Just where the gas for this galactic resurrection came from and how it has created rings remains somewhat perplexing. A merging with a smaller galaxy would bring in fresh gas to spawn hordes of new stars, and could in rare instances give rise to the ring structures as well.


But the researchers have their doubts about this origin scenario. "To create a density shock wave that forms rings like those we've seen, a small galaxy has to hit a larger galaxy pretty much straight in the center," said Salim. "You have to have a dead-on collision, and that's very uncommon."


Rather, the rejuvenating spark more likely came from a gradual sopping-up of the gas in the so-called intergalactic medium, the thin soup of material between galaxies. This external gas could generate these rings, especially in the presence of bar-like structures that span some galaxies' centers.


Ultimately, more observations will be needed to show how these galaxies began growing younger and lit up with humongous halos. Salim and Rich plan to search for more evidence of bars, as well as faint structures that might be the remnants of stellar blooms that occurred in the galaxies' pasts. Rather like recurring seasons, it may be that galaxies stirred from winter can breed stars again and then bask in another vibrant, ultraviolet-soaked summer.


The study detailing the findings appeared in the April 21 issue of the Astrophysical Journal.


The California Institute of Technology in Pasadena leads the Galaxy Evolution Explorer mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. Researchers sponsored by Yonsei University in South Korea and the Centre National d'Etudes Spatiales (CNES) in France collaborated on this mission.


Graphics and additional information about the Galaxy Evolution Explorer are online at http://www.nasa.gov/galex/ and http://www.galex.caltech.edu.


Written by By Adam Hadhazy


Whitney Clavin

(818) 354-4673

Whitney.clavin@jpl.nasa.gov



2010-264
Posted by Nelio Inacio at 6:49 AM 0 comments

Herschel Finds Water in a Cosmic Desert

Herschel Finds Water in a Cosmic Desert:

This Herschel image shows IRC+10216, also known as CW Leonis -- a star rich in carbon where astronomers were surprised to find water.
This Herschel image shows IRC+10216, also known as CW Leonis -- a star rich in carbon where astronomers were surprised to find water.


September 01, 2010

The Herschel infrared space observatory has discovered that ultraviolet starlight is the key ingredient for making water in space. It is the only explanation for why a dying star is surrounded by a gigantic cloud of hot water vapor. Herschel is a European Space Agency mission with important participation from NASA.

Every recipe needs a secret ingredient. When astronomers discovered an unexpected cloud of water vapor around the old star IRC+10216 using NASA's Submillimeter Wave Astronomy Satellite in 2001, they immediately began searching for the source. Stars like IRC+10216 are known as carbon stars and are thought not to make much water. Initially they suspected the star's heat must be evaporating comets or even dwarf planets to produce the water.

Now, Herschel has revealed that the secret ingredient is ultraviolet light, because the water is too hot to have come from the destruction of icy celestial bodies.

"Models predict that there should be no water in the envelopes around stars like this, so astronomers were puzzled about how it got there," said Paul Goldsmith, the NASA project scientist for Herschel at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "These Herschel observations confirm the surprising presence of water vapor in what we thought was an astronomical desert."

This research, which was led by Leen Decin of the Katholieke Universiteit Leuven, Belgium, appears in the Sept. 2 issue of Nature.

Read ESA release

Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at JPL. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA.

More information is online at http://www.herschel.caltech.edu, http://www.nasa.gov/herschel and http://www.esa.int/SPECIALS/Herschel/index.html .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov



2010-281
Posted by Nelio Inacio at 6:48 AM 0 comments

Caught in the Act: Fireballs Light up Jupiter

Caught in the Act: Fireballs Light up Jupiter:

A fleeting bright dot on each of these images of Jupiter marks a small comet or asteroid burning up in the atmosphere.
A fleeting bright dot on each of these images of Jupiter marks a small comet or asteroid burning up in the atmosphere. The image on the left was taken on June 3, 2010, by amateur astronomer Anthony Wesley, who was visiting a friend in Broken Hill, Australia, when he obtained the image with a 37-centimeter (14.5-inch) telescope.

› Full image and caption



September 09, 2010

Amateur astronomers working with professional astronomers have spotted two fireballs lighting up Jupiter's atmosphere this summer, marking the first time Earth-based telescopes have captured relatively small objects burning up in the atmosphere of the giant planet. The two fireballs - which produced bright freckles on Jupiter that were visible through backyard telescopes - occurred on June 3, 2010, and August 20, 2010, respectively.

A new paper that includes both pros and amateurs, led by Ricardo Hueso of the Universidad del País Vasco, Bilbao, Spain, appears today in the Astrophysical Journal Letters. In the paper, astronomers estimate the object that caused the June 3 fireball was 8 to 13 meters (30 to 40 feet) in diameter. The object is comparable in size to the asteroid 2010 RF12 that flew by Earth on Wednesday, Sept. 8, and slightly larger than the asteroid 2008 TC3, which burned up above Sudan two years ago.

An impact of this kind on Earth would not be expected to cause damage on the ground. The energy released by the June 3 fireball as it collided with Jupiter's atmosphere was five to 10 times less than the 1908 Tunguska event on Earth, which knocked over tens of millions of trees in a remote part of Russia. Analysis is continuing on the Aug. 20 fireball, but scientists said it was comparable to the June 3 object.

"Jupiter is a big gravitational vacuum cleaner," said Glenn Orton, a co-author on the paper and an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It is clear now that relatively small objects, remnants of the formation of the solar system 4.5 billion years ago, still hit Jupiter frequently. Scientists are trying to figure out just how frequently."

Orton and colleagues said this kind of discovery couldn't have been made without amateur astronomers around the world, whose observations of Jupiter provide a near round-the-clock surveillance that would be impossible to do with the long lines of scientists waiting to use the large telescopes. Amateur astronomers, for example, were the first to see the dark spot that appeared on Jupiter in July 2009 as the result of an impact. Professional astronomers are still analyzing that impact.

Anthony Wesley, an amateur astronomer from Murrumbateman, Australia, who was also the first to take a picture of that dark spot on Jupiter in July 2009, was the first to see the tiny flash on June 3. Amateur astronomers had their telescopes trained on Jupiter that day because they were in the middle of "Jupiter season," when the planet is high in the sky and at its largest size, as seen by backyard telescopes.

Wesley was visiting an amateur astronomer friend about 1,000 kilometers (600 miles) away in Broken Hill, and he set a digital video camera to record images from his telescope at about 60 frames per second. He was watching the live video on a computer screen at his friend's house when he saw a two-and-a-half-second-long flash of light near the limb of the planet.

"It was clear to me straight away it had to be an event on Jupiter," he said. "I'm used to seeing other momentary flashes in the camera from cosmic ray impacts, but this was different. Cosmic ray strikes last only for one frame of video, whereas this flash gradually brightened and then faded over 133 frames."

Wesley sent a message out on his e-mail list of amateur and professional astronomers, which included Orton. After receiving Wesley's e-mail, Christopher Go of Cebu, Philippines -- who like Wesley, is an amateur astronomer -- checked his own recordings and confirmed that he had seen a flash, too.

Before Wesley's work, scientists didn't know these small-size impacts could be observed, Hueso explained. "The discovery of optical flashes produced by objects of this size helps scientists understand how many of these objects are out there and the role they played in the formation of our solar system," Hueso said.

For three days afterward, Hueso and colleagues looked for signs of the impact in high-resolution images from larger telescopes: NASA's Hubble Space Telescope, Gemini Observatory telescopes in Hawaii and Chile, the Keck telescope in Hawaii, the NASA Infrared Telescope Facility in Hawaii and the European Southern Observatory's Very Large Telescope in Chile. Scientists analyzed the images for thermal disruptions and chemical signatures seen in previous images of Jupiter impacts. In this case, they saw no signs of debris, which allowed them to limit the size of the impactor.

Based on all these images, and particularly those obtained by Wesley and Go, the astronomers were able to confirm the flash came from some kind of object – probably a small comet or asteroid – that burned up in Jupiter's atmosphere. The impactor likely had a mass of about 500 to 2,000 metric tons (1 million to 4 million pounds), probably about 100,000 times less massive than the object in July 2009.

Calculations also estimated this June 3 impact released about 1 to 4 quadrillion joules (300 million to 1 billion kilowatt-hours) of energy. The second fireball, on Aug. 20, was detected by the amateur Japanese astronomer Masayuki Tachikawa and later confirmed by Aoki Kazuo and Masayuki Ishimaru. It flashed for about 1.5 seconds. The Keck telescope, observing less than a day later, also found no subsequent debris remnants. Scientists are still analyzing this second flash.

Although collisions of this size had never before been detected on Jupiter, some previous models predicted around one collision of this kind a year. Another predicted up to 100 such collisions. Scientists now believe the frequency must be closer to the high end of the scale.

"It is interesting to note that whereas Earth gets smacked by a 10-meter-sized object about every 10 years on average, it looks as though Jupiter gets hit with the same-sized object a few times each month," said Don Yeomans, manager of the Near-Earth Object Program Office at JPL, who was not involved in the paper. "The Jupiter impact rate is still being refined and studies like this one help to do just that."

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jia-rui.c.cook@jpl.nasa.gov

2010-293

Posted by Nelio Inacio at 6:48 AM 0 comments

Thumbs Up Given for 2013 NASA Mars Orbiter

Thumbs Up Given for 2013 NASA Mars Orbiter:

Artist's concept of MAVEN Mars orbiter
NASA's MAVEN Mars orbiter, depicted in this artist concept, will explore the mystery of atmospheric-loss on Mars. Image credit: NASA/GFSC


October 05, 2010

PASADENA, Calif. -- NASA has given a green light for development of a 2013 Mars orbiter mission to investigate the mystery of how Mars lost much of its atmosphere: the Mars Atmosphere and Volatile Evolution (Maven) mission.


Clues on the Martian surface, such as features resembling dry riverbeds and minerals that only form in the presence of liquid water, suggest that Mars once had a denser atmosphere, which supported the presence of liquid water on the surface. As part of a dramatic climate change, most of the Martian atmosphere was lost. Maven will make definitive scientific measurements of present-day atmospheric loss that will offer insight into the Red Planet's history.


Approval to proceed with development followed a review at NASA Headquarters of the detailed plans, instrument suite, budget, and risk factor analysis for the spacecraft.


The mission is led by its principal investigator, Bruce Jakosky of the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. NASA Goddard Space Flight Center, Greenbelt, Md., manages the mission, which is part of the NASA Mars Exploration Program managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif.


› Read the full news release
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The Comet Cometh: Hartley 2 Visible in Night Sky

The Comet Cometh: Hartley 2 Visible in Night Sky:

comet Hartley 2
This image of comet Hartley 2 was captured by amateur astronomer Byron Bergert on Oct. 4 in Gainesville, Florida using a 106 mm Takahashi astrograph. Image credit: Byron Bergert


› Larger image


October 19, 2010

Backyard stargazers with a telescope or binoculars and a clear night's sky can now inspect the comet that in a little over two weeks will become only the fifth in history to be imaged close up. Comet Hartley 2 will come within 17.7 million kilometers (11 million miles) of Earth this Wed., Oct. 20 at noon PDT (3 p.m. EDT). NASA's EPOXI mission will come within 700 kilometers (435 miles) of Hartley 2 on Nov. 4.


"On October 20, the comet will be the closest it has ever been since it was discovered in 1986 by Australian astronomer Malcolm Hartley," said Don Yeomans, head of NASA's Near-Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif. and a member of the EPOXI science team. "It's unusual for a comet to approach this close. It is nice of Mother Nature to give us a preview before we see Hartley 2 in all its cometary glory with some great close-up images less than two weeks later."


Comet Hartley 2, also known as 103P/Hartley 2, is a relatively small, but very active periodic comet that orbits the sun once every 6.5 years. From dark, pristine skies in the Northern Hemisphere, the comet should be visible with binoculars as a fuzzy object in the constellation Auriga, passing south of the bright star Capella. Viewing of Hartley 2 from high ambient light locations including urban areas may be more difficult.


In the early morning hours of Oct. 20, the optimal dark sky window for mid-latitude northern observers is under two hours in length. This dark interval will occur between the time when the nearly-full moon sets at about 4:50 a.m. (local time) and when the morning twilight begins at about 6:35 a.m.


By October 22, the comet will have passed through the constellation Auriga. It will continue its journey across the night sky in the direction of the constellation Gemini.


EPOXI is an extended mission that utilizes the already "in-flight" Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft will continue to be referred to as "Deep Impact."


JPL manages the EPOXI mission for NASA's Science Mission Directorate, Washington. The University of Maryland, College Park, is home to the mission's principal investigator, Michael A'Hearn. Drake Deming of NASA's Goddard Space Flight Center, Greenbelt, Md., is the science lead for the mission's extrasolar planet observations. The spacecraft was built for NASA by Ball Aerospace & Technologies Corp., Boulder, Colo.


Images and videos of comet Hartley 2 from both amateur observers and major observatories are online at: http://aop.astro.umd.edu/gallery/hartley.shtml .


For more information about EPOXI visit http://epoxi.umd.edu/ .

DC Agle 818-393-9011

Jet Propulsion Laboratory, Pasadena, Calif.

agle@jpl.nasa.gov



2010-339
Posted by Nelio Inacio at 6:47 AM 0 comments

Five Things About NASA's EPOXI Mission

Five Things About NASA's EPOXI Mission:

Artist's concept of Deep Impact's encounter with comet Temple 1
This artist's concept shows us the first time Deep Impact encountered a comet - Tempel 1 in July 2005. Deep Impact, now in an extended mission called EPOXI, will fly by its next comet, Hartley 2, on Nov. 4, 2010. Image Credit: NASA/JPL-Caltech/UMD


› Full image and caption


October 25, 2010

Here are five quick facts about the EPOXI mission, scheduled to fly by comet Hartley 2 on Nov. 4, 2010.


1. High Fives - This is the fifth time humans will see a comet close-up, and the Deep Impact spacecraft flew by Earth for its fifth time on Sunday, June 27, 2010.


2. Eco-friendly Spacecraft: Recycle, Reuse, Record - The EPOXI mission is recycling the Deep Impact spacecraft, whose probe intentionally collided with comet Tempel 1 on July 4, 2005, revealing, for the first time, the inner material of a comet. The spacecraft is now approaching a second comet rendezvous, a close encounter with Hartley 2 on Nov. 4. The spacecraft is reusing the same trio of instruments used during Deep Impact: two telescopes with digital imagers to record the encounter, and an infrared spectrometer.


3. Small, Mighty and Square-Dancing in Space - Although comet Hartley 2 is smaller than Tempel 1, the previous comet visited by Deep Impact, it is much more active. In fact, amateur skywatchers may be able to see Hartley 2 in a dark sky with binoculars or a small telescope. Engineers specifically designed the mighty Deep Impact spacecraft to point a camera at Tempel 1 while its antenna was directed at Earth. This flyby of comet Hartley 2 does not provide the same luxury. It cannot both photograph the comet and talk with mission controllers on Earth. Engineers have instead programmed Deep Impact to dance the do-si-do. The spacecraft will spend the week leading up to closest approach swinging back and forth between imaging the comet and beaming images back to Earth.


4. Storytelling Comets - Comets are an important aspect of studying how the solar system formed and Earth evolved. Comets are leftover building blocks of solar system formation, and are believed to have seeded an early Earth with water and organic compounds. The more we know about these celestial bodies, the more we can learn about Earth and the solar system.


5. What's in a Name? - EPOXI is a hybrid acronym binding two science investigations: the Extrasolar Planet Observation and Characterization (EPOCh) and Deep Impact eXtended Investigation (DIXI). The spacecraft keeps its original name of Deep Impact, while the mission is called EPOXI.


Priscilla Vega 818-354-1357

Jet Propulsion Laboratory, Pasadena, Calif.

Priscilla.r.vega@jpl.nasa.gov



2010-347
Posted by Nelio Inacio at 6:46 AM 0 comments

WISE Image Reveals Strange Specimen in Starry Sea

WISE Image Reveals Strange Specimen in Starry Sea:

NGC 1514. The view on the left is from a ground-based, visible-light telescope; the view on the right shows the object in infrared light
This image composite shows two views of a puffy, dying star, or planetary nebula, known as NGC 1514. The view on the left is from a ground-based, visible-light telescope; the view on the right shows the object in infrared light, as seen by NASA's Wide-field Infrared Survey Explorer, or WISE. Image credit: NASA/JPL-Caltech/UCLA
› Full image and caption


November 17, 2010

PASADENA, Calif.-- A new image from NASA's Wide-field Infrared Survey Explorer shows what looks like a glowing jellyfish floating at the bottom of a dark, speckled sea. In reality, this critter belongs to the cosmos -- it's a dying star surrounded by fluorescing gas and two very unusual rings.


"I am reminded of the jellyfish exhibition at the Monterey Bay Aquarium -- beautiful things floating in water, except this one is in space," said Edward (Ned) Wright, the principal investigator of the WISE mission at UCLA, and a co-author of a paper on the findings, reported in the Astronomical Journal.


The object, known as NGC 1514 and sometimes the "Crystal Ball" nebula, belongs to a class of objects called planetary nebulae, which form when dying stars toss off their outer layers of material. Ultraviolet light from a central star, or in this case a pair of stars, causes the gas to fluoresce with colorful light. The result is often beautiful -- these objects have been referred to as the butterflies of space.


NGC 1514 was discovered in 1790 by Sir William Herschel, who noted that its "shining fluid" meant that it could not be a faint cluster of stars, as originally suspected. Herschel had previously coined the term planetary nebulae to describe similar objects with circular, planet-like shapes.


Planetary nebulae with asymmetrical wings of nebulosity are common. But nothing like the newfound rings around NGC 1514 had been seen before. Astronomers say the rings are made of dust ejected by the dying pair of stars at the center of NGC 1514. This burst of dust collided with the walls of a cavity that was already cleared out by stellar winds, forming the rings.


"I just happened to look up one of my favorite objects in our WISE catalogue and was shocked to see these odd rings," said Michael Ressler, a member of the WISE science team at NASA's Jet Propulsion Laboratory in Pasadena, Calif., and lead author of the Astronomical Journal paper. Ressler first became acquainted with the object years ago while playing around with his amateur telescope on a desert camping trip. "It's funny how things come around full circle like this."


WISE was able to spot the rings for the first time because their dust is being heated and glows with the infrared light that WISE can detect. In visible-light images, the rings are hidden from view, overwhelmed by the brightly fluorescing clouds of gas.


"This object has been studied for more than 200 years, but WISE shows us it still has surprises," said Ressler.


Infrared light has been color-coded in the new WISE picture, such that blue represents light with a wavelength of 3.4 microns; turquoise is 4.6-micron light; green is 12-micron light; and red is 22-micron light. The dust rings stand out in orange. The greenish glow at the center is an inner shell of material, blown out more recently than an outer shell that is too faint to be seen in WISE's infrared view. The white dot in the middle is the central pair of stars, which are too close together for WISE to see separately.


Ressler says NGC 1514's structure, though it looks unique, is probably similar in overall geometry to other hour-glass nebulae, such as the Engraved Hourglass Nebula (http://hubblesite.org/newscenter/archive/releases/1996/07). The structure looks different in WISE's view because the rings are detectable only by their heat; they do not fluoresce at visible wavelengths, as do the rings in the other objects.


Serendipitous findings like this one are common in survey missions like WISE, which comb through the whole sky. WISE has been surveying the sky in infrared light since January 2010, cataloguing hundreds of millions of asteroids, stars and galaxies. In late September, after covering the sky about one-and-a-half times, it ran out of the frozen coolant needed to chill its longest-wavelength detectors. The mission, now called NEOWISE, is still scanning the skies with two of its infrared detectors, focusing primarily on comets and asteroids, including near-Earth objects, which are bodies whose orbits pass relatively close to Earth's orbit around the sun.


The WISE science team says that more oddballs like NGC 1514 are sure to turn up in the plethora of WISE data -- the first batch of which will be released to the astronomical community in spring 2011.


Other study authors are Martin Cohen of the Monterey Institute for Research in Astronomy, Marina, Calif.; Stefanie Wachter and Don Hoard of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena; and Amy Mainzer of JPL.


JPL manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise , http://wise.astro.ucla.edu and http://www.jpl.nasa.gov/wise .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov




2010-386
Posted by Nelio Inacio at 6:46 AM 0 comments

Tuning an 'Ear' to the Music of Gravitational Waves

Tuning an 'Ear' to the Music of Gravitational Waves:

LISA will be the first space-based mission to attempt the detection of gravitational waves. These are ripples in spacetime that are emitted by exotic objects such as black holes.
This artist’s concept shows the proposed LISA mission, which would consist of three distinct spacecraft, each connected by laser beams. It would be the first space-based mission to attempt the detection of gravitational waves -- ripples in space-time that are emitted by exotic objects such as black holes. Image credit: ESA
› Full image and caption


November 23, 2010

A team of scientists and engineers at NASA's Jet Propulsion Laboratory has brought the world one step closer to "hearing" gravitational waves -- ripples in space and time predicted by Albert Einstein in the early 20th century.


The research, performed in a lab at JPL in Pasadena, Calif., tested a system of lasers that would fly aboard the proposed space mission called Laser Interferometer Space Antenna, or LISA. The mission's goal is to detect the subtle, whisper-like signals of gravitational waves, which have yet to be directly observed. This is no easy task, and many challenges lie ahead.


The new JPL tests hit one significant milestone, demonstrating for the first time that noise, or random fluctuations, in LISA's laser beams can be hushed enough to hear the sweet sounds of the elusive waves.


"In order to detect gravitational waves, we have to make extremely precise measurements," said Bill Klipstein, a physicist at JPL. "Our lasers are much noisier than what we want to measure, so we have to remove that noise carefully to get a clear signal; it's a little like listening for a feather to drop in the middle of a heavy rainstorm." Klipstein is a co-author of a paper about the lab tests that appeared in a recent issue of Physical Review Letters.


The JPL team is one of many groups working on LISA, a joint European Space Agency and NASA mission proposal, which, if selected, would launch in 2020 or later. In August of this year, LISA was given a high recommendation by the 2010 U.S. National Research Council decadal report on astronomy and astrophysics.


One of LISA's primary goals is to detect gravitational waves directly. Studies of these cosmic waves began in earnest decades ago when, in 1974, researchers discovered a pair of orbiting dead stars -- a type called pulsars -- that were spiraling closer and closer together due to an unexplainable loss of energy. That energy was later shown to be in the form of gravitational waves. This was the first indirect proof of the waves, and ultimately earned the 1993 Nobel Prize in Physics.


LISA is expected to not only "hear" the waves, but also learn more about their sources -- massive objects such as black holes and dead stars, which sing the waves like melodies out to the universe as the objects accelerate through space and time. The mission would be able to detect gravitational waves from massive objects in our Milky Way galaxy as well as distant galaxies, allowing scientists to tune into an entirely new language of our universe.


The proposed mission would amount to a giant triangle of three distinct spacecraft, each connected by laser beams. These spacecraft would fly in formation around the sun, about 20 degrees behind Earth. Each one would hold a cube made of platinum and gold that floats freely in space. As gravitational waves pass by the spacecraft, they would cause the distance between the cubes, or test masses, to change by almost imperceptible amounts -- but enough for LISA's extremely sensitive instruments to be able to detect corresponding changes in the connecting laser beams.


"The gravitational waves will cause the 'corks' to bob around, but just by a tiny bit," said Glenn de Vine, a research scientist and co-author of the recent study at JPL. "My friend once said it's sort of like rubber duckies bouncing around in a bathtub."


The JPL team has spent the last six years working on aspects of this LISA technology, including instruments called phase meters, which are sophisticated laser beam detectors. The latest research accomplishes one of their main goals -- to reduce the laser noise detected by the phase meters by one billion times, or enough to detect the signal of gravitational waves.


The job is like trying to find a proton in a haystack. Gravitational waves would change the distance between two spacecraft -- which are flying at 5 million kilometers (3.1 million miles) apart -- by about a picometer, which is about 100 million times smaller than the width of a human hair. In other words, the spacecraft are 5,000,000,000 meters apart, and LISA would detect changes in that distance on the order of .000000000005 meters!


At the heart of the LISA laser technology is a process known as interferometry, which ultimately reveals if the distances traveled by the laser beams of light, and thus the distance between the three spacecraft, have changed due to gravitational waves. The process is like combining ocean waves -- sometimes they pile up and grow bigger, and sometimes they cancel each other out or diminish in size.


"We can't use a tape measure to get the distances between these spacecraft," said de Vine, "So we use lasers. The wavelengths of the lasers are like our tick marks on a tape measure."


On LISA, the laser light is detected by the phase meters and then sent to the ground, where it is "interfered" via data processing (the process is called time-delay interferometry for this reason -- there's a delay before the interferometry technique is applied). If the interference pattern between the laser beams is the same, then that means the spacecraft haven't moved relative to each other. If the interference pattern changes, then they did. If all other reasons for spacecraft movement have been eliminated, then gravitational waves are the culprit.


That's the basic idea. In reality, there are a host of other factors that make this process more complex. For one thing, the spacecraft don't stay put. They naturally move around for reasons that have nothing to do with gravitational waves. Another challenge is the laser beam noise. How do you know if the spacecraft moved because of gravitational waves, or if noise in the laser is just making it seem as if the spacecraft moved?


This is the question the JPL team recently took to their laboratory, which mimics the LISA system. They introduced random, artificial noise into their lasers and then, through a complicated set of data processing actions, subtracted most of it back out. Their recent success demonstrated that they could see changes in the distances between mock spacecraft on the order of a picometer.


In essence, they hushed the roar of the laser beams, so that LISA, if selected for construction, will be able to hear the universe softly hum a tune of gravitational waves.


Other authors of the paper from JPL are Brent Ware; Kirk McKenzie; Robert E. Spero and Daniel A. Shaddock, who has a joint post with JPL and the Australian National University in Canberra.


LISA is a proposed joint NASA and European Space Agency mission. The NASA portion of the mission is managed by NASA's Goddard Space Flight Center, Greenbelt, Md. Some of the key instrumentation studies for the mission are being performed at JPL. The U.S. mission scientist is Tom Prince at the California Institute of Technology in Pasadena. JPL is managed by Caltech for NASA.


Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.
Whitney.clavin@jpl.nasa.gov


2010-394
Posted by Nelio Inacio at 6:45 AM 0 comments

Astronomers Probe 'Sandbar' Between Islands of Galaxies

Astronomers Probe 'Sandbar' Between Islands of Galaxies:

Diagram showing an unusual galaxy with bent jets
This diagram shows an unusual galaxy with bent jets (see inset). Image credit: NASA/JPL-Caltech


› Full image and caption


› See diagram


November 24, 2010

Astronomers have caught sight of an unusual galaxy that has illuminated new details about a celestial "sandbar" connecting two massive islands of galaxies. The research was conducted in part with NASA's Spitzer Space Telescope.


These "sandbars," or filaments, are known to span vast distances between galaxy clusters and form a lattice-like structure known as the cosmic web. Though immense, these filaments are difficult to see and study in detail. Two years ago, Spitzer's infrared eyes revealed that one such intergalactic filament containing star-forming galaxies ran between the galaxy clusters called Abell 1763 and Abell 1770.


Now these observations have been bolstered by the discovery, inside this same filament, of a galaxy that has a rare boomerang shape and unusual light emissions. Hot gas is sweeping the wandering galaxy into this shape as it passes through the filament, presenting a new way to gauge the filament's particle density. Researchers hope that other such galaxies with oddly curved profiles could serve as signposts for the faint threads, which in turn signify regions ripe for forming stars.


"These filaments are integral to the evolution of galaxy clusters -- among the biggest gravitationally bound objects in the universe -- as well as the creation of new generations of stars," said Louise Edwards, a postdoctoral researcher at the California Institute of Technology in Pasadena, and lead author of a study detailing the findings in the Dec. 1 issue of the Astrophysical Journal Letters. Her collaborators are Dario Fadda, also at Caltech, and Dave Frayer from the National Science Foundation's National Radio Astronomy Observatory, based in Charlottesville, Virginia.


Blowing in the cosmic breeze


Astronomers spotted the bent galaxy about 11 million light-years away from the center of the galaxy cluster Abell 1763 during follow-up observations with the WIYN Observatory near Tucson, Ariz., and radio-wave observations by the Very Large Array near Socorro, N.M. The WIYN Observatory is named after the consortium that owns and operates it, which includes the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatories.


The galaxy has an unusual ratio of radio to infrared light, as measured by the Very Large Array and Spitzer, making it stand out like a beacon. This is due in part to the galaxy having twin jets of material spewing in opposite directions from a supermassive black hole at its center. These jets have puffed out into giant lobes of material that emit a tremendous amount of radio waves.


Edwards and her colleagues noticed that these lobes appear to be bent back and away from the galaxy's trajectory through the filament. This bow shape, the astronomers reasoned, is due to particles in the filament pushing on the gas and dust in the lobes.


By measuring the angle of the arced lobes, Edwards' team calculated the pressure exerted by the filaments' particles and then determined the density of the medium. The method is somewhat like looking at streamers on a kite soaring overhead to judge the wind strength and the thickness of the air.


According to the data, the density inside this filament is indeed about 100 times the average density of the universe. This value agrees with that obtained in a previous X-ray study of filaments and also nicely matches predictions of supercomputer simulations.


Interconnected superclusters


Galaxies tend to bunch together as great islands in the void of space, called galaxy clusters. These galaxy groupings themselves often keep company with other clusters in "superclusters" that loom as gargantuan, gravitationally associated walls of galaxies. These structures evolved from denser patches of material as the universe rapidly expanded after the Big Bang, some 13.7 billion years ago.


The clumps and threads of this primordial matter eventually cooled, and some of it has condensed into the galaxies we see today. The leftover gas is strewn in filaments between galaxy clusters. Much of it is still quite hot -- about one million degrees Celsius (1.8 million degrees Fahrenheit) -- and blazes in high-energy X-rays that permeate galaxy clusters. Filaments are therefore best detected in X-ray light, and one direct density reading of the strands has previously been obtained in this band of frequencies.


But the X-ray-emitting gas in filaments is much more diffuse and weak than in clusters, just as submerged sandbars are extremely hard to spot at sea compared to islands poking above the water. Therefore, obtaining quality observations of filaments is time-consuming with current space observatories.


The technique by Edwards and her colleagues, which uses radio frequencies that can reach a host of ground-based telescopes, points to an easier way to probe the interiors of galaxy-cluster filaments. Instead of laboring to find subtle X-rays clues, astronomers could trust these arced "lighthouse" galaxies to indicate just where cosmic filaments lie.


Knowing how much material these filaments contain and how they interact with galaxy clusters will be very important for understanding the overall evolution of the universe, Edwards said.


The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission.


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 Caltech, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer.


Written by Adam Hadhazy



Media Contact:

Whitney Clavin (818) 354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov



2010-396
Posted by Nelio Inacio at 6:44 AM 0 comments

Cassini Returns Images of Bright Jets at Enceladus

Cassini Returns Images of Bright Jets at Enceladus:

NASA's Cassini spacecraft obtained this raw image of the south polar region of Saturn's moon Enceladus on Nov. 30, 2010.
NASA's Cassini spacecraft obtained this raw image of the south polar region of Saturn's moon Enceladus on Nov. 30, 2010. The spacecraft was about 89,000 kilometers (55,000 miles) away from the moon's surface. Image Credit:
NASA/JPL/SSI
› Larger image


December 01, 2010

NASA's Cassini spacecraft successfully dipped near the surface of Saturn's moon Enceladus on Nov. 30.


NASA's Cassini spacecraft successfully dipped near the surface of Saturn's moon Enceladus on Nov. 30. Though Cassini's closest approach took it to within about 48 kilometers (30 miles) of the moon's northern hemisphere, the spacecraft also captured shadowy images of the tortured south polar terrain and the brilliant jets that spray out from it.

Many of the raw images feature darkened terrain because winter has descended upon the southern hemisphere of Enceladus. But sunlight behind the moon backlights the jets of water vapor and icy particles. In some images, the jets line up in rows, forming curtains of spray.

The new raw images can be seen at http://saturn.jpl.nasa.gov/photos/raw/ .

The Enceladus flyby was the 12th of Cassini's mission, with the spacecraft swooping down around 61 degrees north latitude. This encounter and its twin three weeks later at the same altitude and latitude, are the closest Cassini will come to the northern hemisphere surface of Enceladus during the extended Solstice mission. (Cassini's closest-ever approach to Enceladus occurred in October 2008, when the spacecraft dipped to an altitude of 25 kilometers, or 16 miles.)

Among the observations Cassini made during this Enceladus flyby, the radio science subsystem collected gravity measurements to understand the moon's interior structure, and the fields and particles instruments sampled the charged particle environment around the moon.

About two days before the Enceladus flyby, Cassini also passed the sponge-like moon Hyperion, beaming back intriguing images of the craters on its surface. The flyby, at 72,000 kilometers (45,000 miles) in altitude, was one of the closest approaches to Hyperion that Cassini has made.

Scientists are still working to analyze the data and images collected during the flybys.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory manages the project for NASA's Science Mission Directorate in Washington. The Cassini orbiter was designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

More Cassini information is available, at t http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov .

Jia-Rui Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jccook@jpl.nasa.gov


2010-405
Posted by Nelio Inacio at 6:44 AM 0 comments

NASA's Spitzer Reveals First Carbon-Rich Planet

NASA's Spitzer Reveals First Carbon-Rich Planet:

This plot of data from NASA's Spitzer Space Telescope indicates the presence of molecules in the planet WASP-12b
This artist's concept shows the searing-hot gas planet WASP-12b (orange orb) and its star. NASA's Spitzer Space Telescope discovered that the planet has more carbon than oxygen, making it the first carbon-rich planet ever observed. Image credit: NASA/JPL-Caltech
› Full image and caption


December 08, 2010

PASADENA, Calif. -- Astronomers have discovered that a huge, searing-hot planet orbiting another star is loaded with an unusual amount of carbon. The planet, a gas giant named WASP-12b, is the first carbon-rich world ever observed. The discovery was made using NASA's Spitzer Space Telescope, along with previously published ground-based observations.


"This planet reveals the astounding diversity of worlds out there," said Nikku Madhusudhan of the Massachusetts Institute of Technology, Cambridge, lead author of a report in the Dec. 9 issue of the journal Nature. "Carbon-rich planets would be exotic in every way -- formation, interiors and atmospheres."


It's possible that WASP-12b might harbor graphite, diamond, or even a more exotic form of carbon in its interior, beneath its gaseous layers. Astronomers don't currently have the technology to observe the cores of exoplanets, or planets orbiting stars beyond our sun, but their theories hint at these intriguing possibilities.


The research also supports theories that carbon-rich rocky planets much less massive than WASP-12b could exist around other stars. Our Earth has rocks like quartz and feldspar, which are made of silicon and oxygen plus other elements. A carbon-rich rocky planet could be a very different place.


"A carbon-dominated terrestrial world could have lots of pure carbon rocks, like diamond or graphite, as well as carbon compounds like tar," said Joseph Harrington of the University of Central Florida, in Orlando, who is the principal investigator of the research.


Carbon is a common component of planetary systems and a key ingredient of life on Earth. Astronomers often measure carbon-to-oxygen ratios to get an idea of a star's chemistry. Our sun has a carbon-to-oxygen ratio of about one to two, which means it has about half as much carbon as oxygen. None of the planets in our solar system is known to have more carbon than oxygen, or a ratio of one or greater. However, this ratio is unknown for Jupiter, Saturn, Uranus, and Neptune. Unlike WASP-12b, these planets harbor water -- the main oxygen carrier -- deep inside their atmospheres, making it hard to detect.




WASP-12b is the first planet ever to have its carbon-to-oxygen ratio measured at greater than one (the actual ratio is most likely between one and two). This means the planet has excess carbon, some of which is in the form of atmospheric methane.



"When the relative amount of carbon gets that high, it's as though you flip a switch, and everything changes," said Marc Kuchner, an astronomer at NASA Goddard Space Flight Center, Greenbelt, Md., who helped develop the theory of carbon-rich rocky planets but is not associated with the study. "If something like this had happened on Earth, your expensive engagement ring would be made of glass, which would be rare, and the mountains would all be made of diamonds."


Madhusudhan, Harrington and colleagues used Spitzer to observe WASP-12b as it slipped behind its star, in a technique known as secondary eclipse, which was pioneered for exoplanets by Spitzer. These data were combined with previously published observations taken from the ground with the Canada-France-Hawaii Telescope at Mauna Kea, Hawaii. Madhusudhan used the data to conduct a detailed atmospheric analysis, revealing chemicals such as methane and carbon monoxide in the planet's atmosphere.


WASP-12b derives its name from the consortium that found it, the Wide Angle Search for Planets. It is 1.4 times as massive as Jupiter and located roughly 1,200 light-years away from Earth. This blistering world whips around its star in a little over a day, with one side always facing the star. It is so close to its star that the star's gravity stretches the planet into an egg-like shape. What's more, the star's gravity is siphoning mass off the planet into a thin disk that orbits around with it.


The Spitzer data also reveal more information about WASP-12b's temperature. The world was already known to be one of the hottest exoplanets found so far; the new observations indicate that the side that faces the star is 2,600 Kelvin, or 4,200 degrees Fahrenheit. That's more than hot enough to melt steel.


Other authors of the paper are Kevin Stevenson, Sarah Nymeyer, Christopher Campo, Jasmina Blecic, Ryan Hardy, Nate Lust, Christopher Britt and William Bowman of University of Central Florida, Orlando; Peter Wheatley of the University of Warwick, United Kingdom; Drake Deming of NASA Goddard Space Flight Center, Greenbelt, Md.; David Anderson, Coel Hellier and Pierre Maxted of Keele University, United Kingdom; Andrew Collier-Cameron of the University of St. Andrews, United Kingdom; Leslie Hebb of Vanderbilt University, Nashville, Tenn.; Don Pollacco of Queen's University, United Kingdom; and Richard West of the University of Leicester, United Kingdom.


The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer . More information about NASA’s search for exoplanets is at: http://planetquest.jpl.nasa.gov/ .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2010-409
Posted by Nelio Inacio at 6:43 AM 0 comments

Planck Mission Peels Back Layers of the Universe

Planck Mission Peels Back Layers of the Universe:

Clumps of Cold Stuff Across the Sky
This map illustrates the numerous star-forming clouds, called cold cores, that Planck observed throughout our Milky Way galaxy. Image credit: ESA/NASA/JPL-Caltech
› Full image and caption



January 11, 2011

PASADENA, Calif. -- The Planck mission released a new data catalogue Tuesday from initial maps of the entire sky. The catalogue includes thousands of never-before-seen dusty cocoons where stars are forming, and some of the most massive clusters of galaxies ever observed. Planck is a European Space Agency mission with significant contributions from NASA.


"NASA is pleased to support this important mission, and we have eagerly awaited Planck's first discoveries," said Jon Morse, NASA's Astrophysics Division director at the agency's headquarters in Washington. "We look forward to continued collaboration with ESA and more outstanding science to come."


Planck launched in May 2009 on a mission to detect light from just a few hundred thousand years after the Big Bang, an explosive event at the dawn of the universe approximately 13.7 billion years ago. The spacecraft's state-of-the-art detectors ultimately will survey the whole sky at least four times, measuring the cosmic microwave background, or radiation left over from the Big Bang. The data will help scientists decipher clues about the evolution, fate and fabric of our universe. While these cosmology results won't be ready for another two years or so, early observations of specific objects in our Milky Way galaxy, as well as more distant galaxies, are being released.


 "The data we're releasing now are from what lies between us and the cosmic microwave background," said Charles Lawrence, the U.S. project scientist for Planck at NASA's Jet Propulsion Laboratory in Pasadena, Calif. We ultimately will subtract these data out to get at our cosmic microwave background signal. But by themselves, these early observations offer up new information about objects in our universe -- both close and far away, and everything in between."


Planck observes the sky at nine wavelengths of light, ranging from infrared to radio waves. Its technology has greatly improved sensitivity and resolution over its predecessor missions, NASA's Cosmic Background Explorer and Wilkinson Microwave Anisotropy Probe.


The result is a windfall of data on known and never-before-seen cosmic objects. Planck has catalogued approximately 10,000 star-forming "cold cores," thousands of which are newly discovered. The cores are dark and dusty nurseries where baby stars are just beginning to take shape. They also are some of the coldest places in the universe. Planck's new catalogue includes some of the coldest cores ever seen, with temperatures as low as seven degrees above absolute zero, or minus 447 degrees Fahrenheit. In order to see the coldest gas and dust in the Milky Way, Planck's detectors were chilled to only 0.1 Kelvin.


The new catalogue also contains some of the most massive clusters of galaxies known, including a handful of newfound ones. The most massive of these holds the equivalent of a million billion suns worth of mass, making it one of the most massive galaxy clusters known.


Galaxies in our universe are bound together into these larger clusters, forming a lumpy network across the cosmos. Scientists study the clusters to learn more about the evolution of galaxies and dark matter and dark energy -- the exotic substances that constitute the majority of our universe.


"Because Planck is observing the whole sky, it is giving us a comprehensive look at how all the smaller structures of the universe are connected to the whole," said Jim Bartlett, a U.S. Planck team member at JPL and the Astroparticule et Cosmologie-Universite Paris Diderot in France.




Planck's new catalogue also includes unique data on the pools of hot gas that permeate 189 massive clusters of galaxies; 15,000 objects within and outside our galaxy, in addition to the 10,000 cold cores; the best data yet on the cosmic infrared background, which is made up of light from stars evolving in the early universe; and new observations of extremely energetic galaxies spewing radio jets. The catalogue covers about one-and-a-half sky scans.





More information on Planck is online at http://www.nasa.gov/planck and http://www.esa.int/planck . The NASA Planck data archive is at http://irsa.ipac.caltech.edu/Missions/planck.htmlhttp://irsa.ipac.caltech.edu/Missions/planck.html .


Planck is a European Space Agency mission, with significant participation from NASA. NASA's Planck Project Office is based at JPL. JPL contributed mission-enabling technology for both of Planck's science instruments. European, Canadian and U.S. Planck scientists will work together to analyze the Planck data. JPL is managed for NASA by the California Institute of Technology in Pasadena.





Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


Trent Perrotto 202-358-0321

Headquarters, Washington

trent.j.perrotto@nasa.gov



2011-010 
Posted by Nelio Inacio at 6:43 AM 0 comments

Cosmology Standard Candle not so Standard After All

Cosmology Standard Candle not so Standard After All:

Standard Candle in the Wind
This image layout illustrates how NASA's Spitzer Space Telescope was able to show that a "standard candle" used to measure cosmological distances is shrinking -- a finding that affects precise measurements of the age, size and expansion rate of our universe. Image credit: NASA/JPL-Caltech/Iowa State
› Full image and caption


January 12, 2011

PASADENA, Calif. -- Astronomers have turned up the first direct proof that "standard candles" used to illuminate the size of the universe, termed Cepheids, shrink in mass, making them not quite as standard as once thought. The findings, made with NASA's Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age and expansion rate of our universe.


Standard candles are astronomical objects that make up the rungs of the so-called cosmic distance ladder, a tool for measuring the distances to farther and farther galaxies. The ladder's first rung consists of pulsating stars called Cepheid variables, or Cepheids for short. Measurements of the distances to these stars from Earth are critical in making precise measurements of even more distant objects. Each rung on the ladder depends on the previous one, so without accurate Cepheid measurements, the whole cosmic distance ladder would come unhinged.


Now, new observations from Spitzer show that keeping this ladder secure requires even more careful attention to Cepheids. The telescope's infrared observations of one particular Cepheid provide the first direct evidence that these stars can lose mass-or essentially shrink. This could affect measurements of their distances.


"We have shown that these particular standard candles are slowly consumed by their wind," said Massimo Marengo of Iowa State University, Ames, Iowa, lead author of a recent study on the discovery appearing in the Astronomical Journal. "When using Cepheids as standard candles, we must be extra careful because, much like actual candles, they are consumed as they burn."


The star in the study is Delta Cephei, which is the namesake for the entire class of Cepheids. It was discovered in 1784 in the constellation Cepheus, or the King. Intermediate-mass stars can become Cepheids when they are middle-aged, pulsing with a regular beat that is related to how bright they are. This unique trait allows astronomers to take the pulse of a Cepheid and figure out how bright it is intrinsically-or how bright it would be if you were right next to it. By measuring how bright the star appears in the sky, and comparing this to its intrinsic brightness, it can then be determined how far away it must be.


This calculation was famously performed by astronomer Edwin Hubble in 1924, leading to the revelation that our galaxy is just one of many in a vast cosmic sea. Cepheids also helped in the discovery that our universe is expanding and galaxies are drifting apart.


Cepheids have since become reliable rungs on the cosmic distance ladder, but mysteries about these standard candles remain. One question has been whether or not they lose mass. Winds from a Cepheid star could blow off significant amounts of gas and dust, forming a dusty cocoon around the star that would affect how bright it appears. This, in turn, would affect calculations of its distance. Previous research had hinted at such mass loss, but more direct evidence was needed.


Marengo and his colleague used Spitzer's infrared vision to study the dust around Delta Cephei. This particular star is racing along through space at high speeds, pushing interstellar gas and dust into a bow shock up ahead. Luckily for the scientists, a nearby companion star happens to be lighting the area, making the bow shock easier to see. By studying the size and structure of the shock, the team was able to show that a strong, massive wind from the star is pushing against the interstellar gas and dust. In addition, the team calculated that this wind is up to one million times stronger than the wind blown by our sun. This proves that Delta Cephei is shrinking slightly.



Follow-up observations of other Cepheids conducted by the same team using Spitzer have shown that other Cepheids, up to 25 percent observed, are also losing mass.


"Everything crumbles in cosmology studies if you don't start up with the most precise measurements of Cepheids possible," said Pauline Barmby of the University of Western Ontario, Canada, lead author of the follow-up Cepheid study published online Jan. 6 in the Astronomical Journal. "This discovery will allow us to better understand these stars, and use them as ever more precise distance indicators."


Other authors of this study include N. R. Evans and G.G. Fazio of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.; L.D. Matthews of Harvard-Smithsonian and the Massachusetts Institute of Technology Haystack Observatory, Westford; G. Bono of the Università di Roma Tor Vergata and the INAF-Osservatorio Astronomico di Roma in Rome, Italy; D.L. Welch of the McMaster University, Ontario, Canada; M. Romaniello of the European Southern Observatory, Garching, Germany; D. Huelsman of Harvard-Smithsonian and University of Cincinnati, Ohio; and K. Y. L. Su of the University of Arizona, Tucson.


The Spitzer observations were made before it ran out of its liquid coolant in May 2009 and began its warm mission.


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, also in Pasadena. Caltech manages JPL for NASA. For more information about Spitzer, visit http://spitzer.caltech.edu/ and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov


2011-012
Posted by Nelio Inacio at 6:43 AM 0 comments

Earth-Size Planet Candidates Found in Habitable Zone

Earth-Size Planet Candidates Found in Habitable Zone:

Kepler-11 Planetary System
This artist's concept shows Kepler-11 -- the most tightly packed planetary system yet discovered. Image credit: NASA/Ames/JPL-Caltech › Full image and caption


February 02, 2011

PASADENA, Calif. -- NASA's Kepler mission has discovered its first Earth-size planet candidates and its first candidates in the habitable zone, a region where liquid water could exist on a planet's surface. Five of the potential planets are near Earth-size and orbit in the habitable zone of smaller, cooler stars than our sun.

Candidates require follow-up observations to verify they are actual planets. Kepler also found six confirmed planets orbiting a sun-like star, Kepler-11. This is the largest group of transiting planets orbiting a single star yet discovered outside our solar system.

"In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today's reality," said NASA Administrator Charles Bolden. "These discoveries underscore the importance of NASA's science missions, which consistently increase understanding of our place in the cosmos."

The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size -- up to twice the size of Earth -- to larger than Jupiter.

The findings are based on the results of observations conducted May 12 to Sept. 17, 2009, of more than 156,000 stars in Kepler's field of view, which covers approximately one four-hundredth of the sky.

"The fact that we've found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting sun-like stars in our galaxy," said William Borucki of NASA's Ames Research Center in Moffett Field, Calif., the mission's science principal investigator. "We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone, some of which could have moons with liquid water."

Among the stars with planetary candidates, 170 show evidence of multiple planetary candidates. Kepler-11, located approximately 2,000 light years from Earth, is the most tightly packed planetary system yet discovered. All six of its confirmed planets have orbits smaller than Venus, and five of the six have orbits smaller than Mercury's. The only other star with more than one confirmed transiting planet is Kepler-9, which has three. The Kepler-11 findings will be published in the Feb. 3 issue of the journal Nature.

"Kepler-11 is a remarkable system whose architecture and dynamics provide clues about its formation," said Jack Lissauer, a planetary scientist and Kepler science team member at Ames. "These six planets are mixtures of rock and gases, possibly including water. The rocky material accounts for most of the planets' mass, while the gas takes up most of their volume. By measuring the sizes and masses of the five inner planets, we determined they are among the lowest-mass confirmed planets beyond our solar system."

All of the planets orbiting Kepler-11 are larger than Earth, with the largest ones being comparable in size to Uranus and Neptune. The innermost planet, Kepler-11b, is 10 times closer to its star than Earth is to the sun. Moving outward, the other planets are Kepler-11c, Kepler-11d, Kepler-11e, Kepler-11f, and the outermost planet, Kepler-11g, which is half as far from its star as Earth is from the sun.

The planets Kepler-11d, Kepler-11e and Kepler-11f have a significant amount of light gas, which indicates that they formed within a few million years of the system's formation.

"The historic milestones Kepler makes with each new discovery will determine the course of every exoplanet mission to follow," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.

Kepler, a space telescope, looks for planet signatures by measuring tiny decreases in the brightness of stars caused by planets crossing in front of them. This is known as a transit. Since transits of planets in the habitable zone of sun-like stars occur about once a year and require three transits for verification, it is expected to take three years to locate and verify Earth-size planets orbiting sun-like stars.

The Kepler science team uses ground-based telescopes and NASA's Spitzer Space Telescope to review observations on planetary candidates and other objects of interest the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

Ames manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters. JPL is a division of the California Institute of Technology in Pasadena.


For more information about the Kepler mission, visit: http://www.nasa.gov/kepler . More information about NASA's planet-hunting efforts is online at: http://planetquest.jpl.nasa.gov/ .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov

Trent Perrotto 202-358-0321

Headquarters, Washington

trent.j.perrotto@nasa.gov


2011-036
Posted by Nelio Inacio at 6:41 AM 0 comments
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