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Friday, February 28, 2014

715 New, Verified Planets


Years ago, before the launch of NASA’s Kepler spacecraft, astronomers were thrilled when they discovered a single planet.

Today, the Kepler team announced 715.

Kepler has always been good at finding planets. Even before the announcement, the observatory had confirmed 246 new worlds outside the solar system. The latest discoveries almost quadruple that number.

Kepler works by looking for the slight dimming of starlight caused when a distant planet transits its parent star. Any dip in stellar brightness attracts the attention of the Kepler team, and can prompt them to declare a planet candidate. Verification of candidates can be a laborious process, proceeding slowly, planet-by-planet.

Now, however, a research team co-led by Jack Lissauer of the Ames Research Center has figured out a way to speed the process up.

"We've developed a procedure to verify multiple planet candidates in bulk to deliver planets wholesale, and have used it to unveil a veritable bonanza of new worlds," says Lissauer.

The technique is called "verification by multiplicity," which relies in part on the logic of probability. Out of the 160,000 stars Kepler has observed, a few thousand have planet candidates. But not all candidate systems are equal. A subset of the total, numbering in the hundreds, have not just one but multiple candidates. By concentrating on those busy systems, the team found 715 planets orbiting 305 stars.

The method of multiplicity can be likened to the behavior of lions and lionesses. Suppose that Kepler’s stars are like lions, and the planets are lionesses. If you see two big cats it could be a lion and a lioness or it could be two lions. But if more than two cats are gathered, then it is very likely a lion and his pride. Thus, through multiplicity, the lionesses—or planets—can be reliably identified.

All of the newly-discovered worlds are located in multi-planet systems. Nearly 95 percent of the planets are smaller than Neptune—that is, less than four times the size of Earth. This is a marked increase in the known number of relatively small planets.

“This study shows us that planets in multi-systems tend to be small and their orbits are flat and circular, much like the inner parts of our own solar system,” says Jason Rowe a co-leader of the research at the SETI Institute.

Four of the new planets are less than two-and-a-half times the size of Earth. Moreover, they orbit in their sun's habitable zone, where the surface temperature of the planets may be suitable for liquid water, a key ingredient for life as we know it.

"The more we explore," concludes Rowe, "the more we find familiar traces of ourselves amongst the stars that remind us of home."

Video credit: NASA

Note: For more information, see PIA17848: Star System Bonanza (Illustration).

Thursday, February 27, 2014

Asteroid 2006 DP14


This image is one frame from a collage of radar images taken on February 11, 2014, of near-Earth asteroid 2006 DP 14, which is about 1,300 feet (400 meters) long. The imaging used the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California, while the asteroid was about 11 times farther from Earth than the moon is.

A collage of radar images of near-Earth asteroid 2006 DP14 was generated by NASA scientists using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, California, on the night of February 11, 2014.

Delay-Doppler radar imaging revealed that the asteroid is about 1,300 feet (400 meters) long, 660 feet (200 meters) wide, and shaped somewhat like a big peanut. The asteroid's period of rotation is about six hours. The asteroid is of a type known as a "contact binary" because it has two large lobes on either end that appear to be in contact. Previous radar data from Goldstone and the Arecibo Observatory in Puerto Rico has shown that at least 10 percent of near-Earth asteroids larger than about 650 feet (200 meters) have contact binary shapes like that of 2006 DP14. The data were obtained over an interval of 2.5 hours as the asteroid completed about half a revolution. The resolution is about 60 feet (19 meters) per pixel.

The data were obtained on February 11 between 9:03 a.m. and 11:27 p.m. PST (12:03 a.m. to 2:27 a.m. EST on February 12). At the time of the observations, the asteroid's distance was about 2.6 million miles (4.2 million kilometers) from Earth. That is about 11 times the average distance between Earth and its moon. The asteroid's closest approach to Earth occurred on February 10, at a distance of about 1.5 million miles (2.4 million kilometers).

Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.

NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the United States has the most robust and productive survey and detection program for discovering near-Earth objects. To date, U.S. assets have discovered more than 98 percent of the known near-Earth objects.

Image credit: NASA/JPL-Caltech/GSSR

Wednesday, February 26, 2014

NGC 5044


This image shows a composite view of the giant elliptical galaxy NGC 5044.

The stellar component, as observed at optical wavelengths, is shown in white at the center of the image. The other stars scattered around the image are foreground stars from our own Galaxy.

The galaxy is embedded in a hot atmosphere of ionized hydrogen gas, which is shown in blue. With temperatures up to tens of millions of K, the hot gas shines brightly in X-rays and was observed using NASA's Chandra X-ray Observatory.

Observations show that some of the hot gas cools down and flows towards the center of the galaxy. There, the cold gas may condense and form stars, unless it is reheated or expelled from the galaxy by other agents.

The filamentary network shown in red is warm hydrogen gas, as observed in the H-alpha emission line at a rest wavelength of 656.28 nm with the Southern Observatory for Astrophysical Research (SOAR) telescope in Chile.

When observed in radio wavelengths, this galaxy appears only as the weak source shown in violet at the center of the image, which belies the moderately active black hole sitting at the center of the galaxy. The radio observations were performed with NRAO's Very Large Array (VLA).

A team of astronomers has observed NGC 5044 and other nearby giant elliptical galaxies using ESA's Herschel Space Observatory, to try to figure out why galaxies of this type do not form stars. Spectroscopic observations obtained with Herschel showed that, contrary to previous belief, NGC 5044 contains plenty of cold gas – the raw material to form stars. The same holds true for most of the giant elliptical galaxies that the team observed.

A multi-wavelength study suggests that, while hot gas cools down in these galaxies, stars do not form because of feedback from the central supermassive black hole, which stirs up the gas preventing it from turning into stars.

Image credit: Digitized Sky Survey/NASA Chandra/Southern Observatory for Astrophysical Research/Very Large Array (Robert Dunn et al. 2010)

Note: For more information, see Bullying Black Holes Force Galaxies to Stay Red and Dead.

Tuesday, February 25, 2014

Mawrth Vallis and Rosetta's Self-Portrait


On 25 February 2007 at 02:15 GMT, Rosetta passed just 250 km from the surface of Mars. Rosetta’s Philae lander took this image 4 minutes before closest approach, at a distance of 1000 km. It captures one of Rosetta’s 14 m-long solar wings, set against the northern hemisphere of Mars, where details in the Mawrth Vallis region can be seen.

Mawrth Vallis is of particular interest to scientists because it contains minerals formed in the presence of water – a discovery made by ESA’s Mars Express.

This image was originally published in 2007 and was taken in black-and-white. Representative color was added to the surface of Mars and, in this version, these colors have been slightly enhanced, along with some brightening of details in the solar wing.

On Sunday 2 March, Rosetta celebrates ten years since launch. The flyby at Mars was one of four planetary gravity assists (the other three were at Earth) needed to boost the spacecraft onto the correct trajectory to meet up with its target, comet 67P/Churyumov–Gerasimenko, in August 2014.

Rosetta will become the first space mission to rendezvous with a comet, the first to attempt a landing, and the first to follow a comet as it swings around the Sun.

Image credit: ESA/Rosetta/Philae/CIVA

Sunday, February 23, 2014

Crescent Moon from the ISS


On February 1, 2014, Japan Aerospace Exploration Agency astronaut Koichi Wakata tweeted this view of a crescent moon rising and the cusp of Earth's atmosphere. Distinct colors are visible because the dominant gases and particles in each layer of the atmosphere act as prisms, filtering out certain colors of light.

Image credit: NASA

Saturday, February 22, 2014

Bow Shock Wave from Kappa Cassiopeiae


The red arc in this infrared image from NASA's Spitzer Space Telescope is a giant shock wave, created by a speeding star known as Kappa Cassiopeiae.

Roguish runaway stars can have a big impact on their surroundings as they plunge through the Milky Way galaxy. Their high-speed encounters shock the galaxy, creating arcs, as seen in this newly released image from NASA's Spitzer Space Telescope.

In this case, the speedster star is known as Kappa Cassiopeiae, or HD 2905 to astronomers. It is a massive, hot supergiant moving at around 2.5 million mph relative to its neighbors (1,100 kilometers per second). But what really makes the star stand out in this image is the surrounding, streaky red glow of material in its path. Such structures are called bow shocks, and they can often be seen in front of the fastest, most massive stars in the galaxy.

Bow shocks form where the magnetic fields and wind of particles flowing off a star collide with the diffuse, and usually invisible, gas and dust that fill the space between stars. How these shocks light up tells astronomers about the conditions around the star and in space. Slow-moving stars like our sun have bow shocks that are nearly invisible at all wavelengths of light, but fast stars like Kappa Cassiopeiae create shocks that can be seen by Spitzer's infrared detectors.

Incredibly, this shock is created about 4 light-years ahead of Kappa Cassiopeiae, showing what a sizable impact this star has on its surroundings. (This is about the same distance that we are from Proxima Centauri, the nearest star beyond the sun.)

The Kappa Cassiopeiae bow shock shows up as a vividly red color. The faint green features in this image result from carbon molecules, called polycyclic aromatic hydrocarbons, in dust clouds along the line of sight that are illuminated by starlight.

Delicate red filaments run through this infrared nebula, crossing the bow shock. Some astronomers have suggested these filaments may be tracing out features of the magnetic field that runs throughout our galaxy. Since magnetic fields are completely invisible themselves, we rely on chance encounters like this to reveal a little of their structure as they interact with the surrounding dust and gas.

Kappa Cassiopeiae is visible to the naked eye in the Cassiopeia constellation (but its bow shock only shows up in infrared light.)

For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red.

Image credit: NASA/JPL-Caltech

Friday, February 21, 2014

Messier 7


This new image from the Wide Field Imager on the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile, shows the bright star cluster Messier 7, also known as NGC 6475. Easily spotted by the naked eye in the direction of the tail of the constellation of Scorpius (The Scorpion), this cluster is one of the most prominent open clusters of stars in the sky and an important research target.

Photo credit: ESO

Note: For more information, see Diamonds in the Tail of the Scorpion.

Thursday, February 20, 2014

Cassiopeia A


The mystery of how Cassiopeia A exploded is unraveling thanks to new data from NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR. In this image, NuSTAR data, which show high-energy X-rays from radioactive material, are colored blue. Lower-energy X-rays from non-radioactive material, imaged previously with NASA's Chandra X-ray Observatory, are shown in red, yellow and green.

The new view shows a more complete picture of Cassiopeia A, the remains of a star that blew up in a supernova event whose light reached Earth about 350 years ago, when it could have appeared to observers as a star that suddenly brightened. The remnant is located 11,000 light-years away from Earth.

NuSTAR is the first telescope capable of taking detailed pictures of the radioactive material in the Cassiopeia A supernova remnant. While other telescopes have detected radioactivity in these objects before, NuSTAR is the first capable of pinpointing the location of the radioactivity, creating maps. When massive star explode, they create many elements: non-radioactive ones like iron and calcium found in your blood and bones; and radioactive elements like titanium-44, the decay of which sends out high-energy X-ray light that NuSTAR can see.

By mapping titanium-44 in Cassiopeia A, astronomers get a direct look at what happened in the core of the star when it was blasted to smithereens. These NuSTAR data complement previous observations made by Chandra, which show elements, such as iron, that were heated by shock waves farther out from the remnant's center.

In this image, the red, yellow and green data were collected by Chandra at energies ranging from 1 to 7 kiloelectron volts (keV). The red color shows heated iron, and green represents heated silicon and magnesium. The yellow is what astronomers call continuum emission, and represents a range of X-ray energies.

The titanium-44, shown in blue, was detected by NuSTAR at energies ranging between 68 and 78 keV.

The NuSTAR observations point to a possible solution to the puzzle of how stars detonate. The fact that the titanium -- which is a direct tracer of the supernova blast -- is concentrated in clumps at the core supports a theory referred to as "mild asymmetries." In this scenario, material sloshes about at the heart of the supernova, reinvigorating a shock wave and allowing it to blow out the star's outer layers.

Image credit: NASA/JPL-Caltech/CXC/SAO

Note: For more information, see PIA17839: Adding a New "Color" to Palate of Cassiopeia A Images, PIA17840: The Creation of Titanium in Stars, PIA17841: Radioactive Core of a Dead Star, PIA17842: The Case of Missing Iron in Cassiopeia A, PIA17844: Evolution of a Supernova, PIA17846: NuSTAR Data Point to Sloshing Supernovas, PIA17845: Sloshing Star Goes Supernova, NASA's NuSTAR Untangles Mystery of How Stars Explode, and Supernovas Slosh Before Exploding.

Wednesday, February 19, 2014

IGR J11014-6103


IGR J11014-6103: A pulsar moving at supersonic speeds about 23,000 light years from Earth.

An extraordinary jet trailing behind a runaway pulsar is seen in this composite image that contains X-ray data from Chandra (purple), radio data from the ACTA (green), and optical data from the 2MASS survey (red, green, and blue). The pulsar – a spinning neutron star – and its tail are found in the lower right of this image. The tail stretches for 37 light years, making it the longest X-ray jet ever seen from an object in the Milky Way galaxy. The pulsar is moving away from the center of the supernova remnant (seen in the upper left of the image) where it was born at a speed between 2.5 million and 5 million miles per hour. This supersonic pace makes IGR J1104-6103 one of the fastest moving pulsars ever observed.

Scale: Image is 22 arcmin across (about 147 light years).

Image credit: X-ray: NASA/CXC/ISDC/L.Pavan et al, Radio: CSIRO/ATNF/ATCA Optical: 2MASS/UMass/IPAC-Caltech/NASA/NSF

Note: For more information, see IGR J11014-6103: Runaway Pulsar Firing an Extraordinary Jet.

Friday, February 14, 2014

Ganymede Geological Map


Animation of a rotating globe of Jupiter's moon Ganymede, with a geologic map superimposed over a global color mosaic. The 37-second animation begins as a global color mosaic image of the moon then quickly fades in the geologic map.

The views incorporate the best available imagery from NASA's Voyager 1 and 2 spacecraft and NASA's Galileo spacecraft.


To present the best information in a single view of Jupiter's moon Ganymede, a global image mosaic was assembled, incorporating the best available imagery from NASA's Voyager 1 and 2 spacecraft and NASA's Galileo spacecraft. This image shows Ganymede centered at 200 west longitude. This mosaic (right) served as the base map for the geologic map of Ganymede (left).

Video credit (top): USGS Astrogeology Science Center/Wheaton/ASU/NASA/JPL-Caltech; image credit (bottom): USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech

Note: For more information, see Largest Solar System Moon Detailed in Geologic Map.

Thursday, February 13, 2014

Coronal Hole


The dark region seen on the face of the sun at the end of March 2013 is a coronal hole (just above and to the right of the middle of the picture), which is a source of fast solar wind leaving the sun. As it traveled through the solar system, this high-speed stream of plasma pushed up against slower solar wind ahead of it, and eventually formed a high-pressure region. This high-pressure region crashed into Saturn's magnetic bubble several weeks later in May 2013, causing bright auroral displays.

This image was obtained by the atmospheric imaging assembly on NASA's Solar Dynamic Observatory on March 28, 2013.

Image credit: NASA/SDO/AIA

Wednesday, February 12, 2014

Saturn's Auroras


Ultraviolet and infrared images from NASA's Cassini spacecraft and Hubble Space Telescope show active and quiet auroras at Saturn's north and south poles.

Saturn's auroras glow when energetic electrons dive into the planet's atmosphere and collide with hydrogen molecules. Sometimes a blast of fast solar wind, composed of mostly electrons and protons, creates an active aurora at Saturn, as occurred on April 5 and May 20, 2013.

The first set of images, as seen in the ultraviolet part of the spectrum by Hubble, shows an active aurora dancing around Saturn's north pole on April 5. The movie then shows a relatively quiet time between April 19 to 22 and between May 18 and 19. The aurora flares up again in Hubble images from May 20. This version, shown in false-color, has been processed to show the auroras more clearly.

A second set of ultraviolet images shows a closer view of an active north polar aurora in white. This set comes from Cassini ultraviolet imaging spectrograph observations on May 20 and 21.

The last set of images, in the infrared, shows a quiet southern aurora (in green) in observations from Cassini's visual and infrared mapping spectrometer on May 17. Saturn's inner heat glows in red, with dark areas showing where high clouds block the heat.

Video credit: NASA/JPL-Caltech/University of Colorado/Central Arizona College and NASA/ESA/University of Leicester and NASA/JPL-Caltech/University of Arizona/Lancaster University

Note: For more information, see PIA17668: Saturn's Colorful Aurora and NASA Spacecraft Get a 360-Degree View of Saturn's Auroras.

Tuesday, February 11, 2014

Abell 2744Y1


This image of the galaxy cluster Abell 2744 was obtained with NASA's Hubble Space Telescope. The zoomed image shows the region around the galaxy Abell2744_Y1, one of the most distant galaxy candidates known, harkening back to a time when the universe was 650 million years old. NASA's Spitzer Space Telescope helped to narrow in on the galaxy's great distance.

The galaxy was found with the help of a gravitational lens: gravity from the mass in Abell 2744 acts to magnify the light of more distant galaxies behind it.

These observations were part of NASA's Frontier Fields program, designed to push the limits of how far we can see into the early universe.

See PIA17569 for a full view of the galaxy cluster Abell 2744.

Image credit: NASA/ESA/STScI/IAC

Note: For more information, see Looking Back to the Cradle of Our Universe.

Monday, February 10, 2014

NGC 5128 - Centaurus A


Centaurus A: An active galaxy about 12 million light years from Earth.

Centaurus A is a galaxy well known for a gargantuan jet blasting away from a central supermassive black hole, which is seen in this new Chandra image. This image - where red, medium,and blue show low, medium, and high-energy X-rays respectively - has been processed with new techniques and contains data from observations equivalent to over nine and a half days worth of observing time taken between 1999 and 2012. The data housed in Chandra's extensive archive on Centaurus A provide a rich resource for a wide range of scientific investigations, including a recent study that examines the population and characteristics of black holes and neutron stars throughout the galaxy.

Scale: Image is 16.7 arcmin (about 58,000 light years)

Image credit: X-ray: NASA/CXC/U.Birmingham/M.Burke et al.

Note: For more information, see Centaurus A: A New Look at an Old Friend.

Sunday, February 9, 2014

NGC 1818


A Gaia test image of the young star cluster NGC 1818 in the Large Magellanic Cloud, taken as part of calibration and testing before the science phase of the mission begins. The field-of-view is 212 x 212 arcseconds and the image is approximately oriented with north up and east left. The integration time of the image was 2.85 seconds and the image covers an area less than 1% of the full Gaia field of view.

Gaia’s overall design is optimized for making precise position measurements and the primary mirrors of its twin telescopes are rectangular rather than round. To best match the images delivered by the telescopes, the pixels in Gaia’s focal plane detectors are then also rectangular. In order to produce this image of NGC 1818, the image has been resampled onto square pixels. Furthermore, to maximize its sensitivity to very faint stars, Gaia’s main camera does not use filters and provides wide-band intensity data, not true-color images. The false-color scheme used here relates to intensity only. The real colors and spectral properties of the stars are measured by other Gaia instruments.

Photo credit: ESA/DPAC/Airbus DS

Note: For more information, see Gaia Comes Into Focus.

Saturday, February 8, 2014

The Earth and Moon from Mars



This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth. Two annotated versions of this image are also available in Figures 1 and 2.

Researchers used the left eye camera of Curiosity's Mast Camera (Mastcam) to capture this scene about 80 minutes after sunset on the 529th Martian day, or sol, of the rover's work on Mars (January 31, 2014). The image has been processed to remove effects of cosmic rays.

A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright "evening stars."

The distance between Earth and Mars when Curiosity took the photo was about 99 million miles (160 million kilometers).

Photo credit: NASA/JPL-Caltech/MSSS/TAMU

Note: For more information, see PIA17935: Curiosity Mars Rover's First Image of Earth and Earth's Moon and NASA Mars Rover Curiosity Sees 'Evening Star' Earth.

Friday, February 7, 2014

Structural Composition of Asteroid 25143 Itokawa


A schematic view of the strange peanut-shaped asteroid Itokawa.

By making exquisitely precise timing measurements using ESO’s New Technology Telescope, and combining them with a model of the asteroid's surface topography, a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form. The shape model used for this view is based on the images collected by JAXA's Hayabusa spacecraft.


This very detailed view shows the strange peanut-shaped asteroid Itokawa. By making exquisitely precise timing measurements using ESO’s New Technology Telescope a team of astronomers has found that different parts of this asteroid have different densities. As well as revealing secrets about the asteroid’s formation, finding out what lies below the surface of asteroids may also shed light on what happens when bodies collide in the Solar System, and provide clues about how planets form.

This picture comes from the Japanese spacecraft Hayabusa during its close approach in 2005.

Top illustration credit: ESO. Acknowledgement: JAXA. Bottom photo credit: JAXA

Note: For more information, see The Anatomy of an Asteroid.

Thursday, February 6, 2014

New Impact Crater in Syrtis Major Planum


A dramatic, fresh impact crater dominates this image taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter on November 19, 2013. Researchers used HiRISE to examine this site because the orbiter's Context Camera had revealed a change in appearance here between observations in July 2010 and May 2012, bracketing the formation of the crater between those observations.

The crater spans approximately 100 feet (30 meters) in diameter and is surrounded by a large, rayed blast zone. Because the terrain where the crater formed is dusty, the fresh crater appears blue in the enhanced color of the image, due to removal of the reddish dust in that area. Debris tossed outward during the formation of the crater is called ejecta. In examining ejecta's distribution, scientists can learn more about the impact event. The explosion that excavated this crater threw ejecta as far as 9.3 miles (15 kilometers).

The crater is at 3.7 degrees north latitude, 53.4 degrees east longitude on Mars. Before-and-after imaging that brackets appearance dates of fresh craters on Mars has indicated that impacts producing craters at least 12.8 feet (3.9 meters) in diameter occur at a rate exceeding 200 per year globally. Few of the scars are as dramatic in appearance as this one.

This image is one product from the HiRISE observation cataloged as ESP_034285_1835. Other products from the same observation are available at http://uahirise.org/ESP_034285_1835.

Image credit: NASA/JPL/University of Arizona

Note: For more information, see A Spectacular New Impact Crater and Its Ejecta and NASA Mars Orbiter Examines Dramatic New Crater. This crater is located in Syrtis Major Planum to the northwest of Schroeter Crater.

Wednesday, February 5, 2014

Wobbly Planet Kepler-413b


This illustration shows the unusual orbit of planet Kepler-413b around a close pair of orange and red dwarf stars. The planet's 66-day orbit is tilted 2.5 degrees with respect to the plane of the binary stars' orbit. The orbit of the planet wobbles around the central stars over 11 years, an effect called precession. This planet is also very unusual in that it can potentially precess wildly on its spin axis, much like a child's top.

The tilt of the spin axis of the planet can vary by as much as 30 degrees over 11 years, presumably leading to the rapid and erratic changes in seasons on the planet and any accompanying large moons that might exist there.

As Kepler views the system nearly edge on, sometimes the planet passes in front of the binary pair, and sometimes it does not. The next transit is not predicted to occur until 2020. This is due not only to the orbital wobble, but also to the small diameters of the stars and the fact that the orbital plane of the stars is not exactly edge-on to Kepler's line of sight.

The vertical axis on the right panel is exaggerated by a factor of 10, for viewing purposes only.

Illustration credit: NASA/ESA/STScI

Note: For more information, see Kepler Finds a Very Wobbly Planet (JPL News) and Kepler Finds a Very Wobbly Planet (NASA Science News).

Tuesday, February 4, 2014

Building Malargüe Station


Time-compressed video compiled from hourly webcam images showing the construction of ESA's 35m deep-space ground tracking station at Malargüe, Argentina, in 2010. Scenes include ground breaking, construction of the base and rotating antenna support module, assembling the giant parabolic reflector dish, lifting the dish into place and final stages of pre-commissioning. The station was formally inaugurated in December 2012.

Video credit: ESA

Monday, February 3, 2014

Herbig-Haro 30


Herbig-Haro 30 is the prototype of a gas-rich "young stellar object" disk around a star. The dark disk spans 40 billion miles (64 billion kilometers) in this image from NASA's Hubble Space Telescope, cutting the bright nebula in two and blocking the central star from direct view. Volunteers can help astronomers find more disks like this through DiskDetective.org, which incorporates data from NASA's Wide-field Infrared Survey Explorer, or WISE.

This image was taken by Hubble's former instrument, the Wide Field Planetary Camera 2, built by NASA's Jet Propulsion Laboratory, Pasadena, California.

Photo credit: NASA/Hubble/STScI

Note: For more information, see NASA-Sponsored 'Disk Detective' Lets Public Search for New Planetary Nurseries.

Sunday, February 2, 2014

Development of Massive Elliptical Galaxies


This graphic shows the evolutionary sequence in the growth of massive elliptical galaxies over 13 billion years, as gleaned from space-based and ground-based telescopic observations. The growth of this class of galaxies is quickly driven by rapid star formation and mergers with other galaxies.

Astronomers using NASA's Hubble and Spitzer space telescopes, and Europe's Herschel Space Observatory, have pieced together the evolutionary sequence of compact elliptical galaxies that erupted and burned out early in the history of the universe.

Enabled by Hubble's infrared imaging capabilities, astronomers have assembled for the first time a representative spectroscopic sampling of ultra-compact, burned-out elliptical galaxies -- galaxies whose star formation was finished when the universe was only 3 billion years old, less than a quarter of its current estimated age of 13.8 billion years.

The research, supported by several ground-based telescopes, solves a 10-year-old mystery about the growth of the most massive elliptical galaxies we see today. It provides a clear picture of the formation of the most massive galaxies in the universe, from their initial burst of star formation through their development of dense stellar cores, to their ultimate reality as giant ellipticals.

"We at last show how these compact galaxies can form, how it happened, and when it happened. This basically is the missing piece in the understanding of how the most massive galaxies formed, and how they evolved into the giant ellipticals of today," said Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute in Copenhagen, Denmark, who is the leader of this study.

"This had been a great mystery for many years because just 3 billion years after the big bang we see that half of the most massive galaxies have already completed their star formation."

Through the research, astronomers have determined the compact ellipticals voraciously consumed the gas available for star formation, to the point they could not create new stars, and then merged with smaller galaxies to form giant ellipticals. The stars in the burned-out galaxies were packed 10 to 100 times more densely than in equally massive elliptical galaxies seen in the nearby universe today, and that surprised astronomers, according to Toft.

To develop the evolutionary sequence for ultra-compact, burned-out galaxies, Toft's team assembled, for the first time, representative samples of two galaxy populations using the rich dataset in Hubble's COSMOS (Cosmic Evolution Survey) program.

One group of galaxies is the compact ellipticals. The other group contains galaxies that are highly obscured with dust and undergoing rapid star formation at rates thousands of times faster than observed in the Milky Way. Starbursts in these dusty galaxies likely were ignited when two gas-rich galaxies collided. These galaxies are so dusty that they are almost invisible at optical wavelengths, but they shine bright at submillimeter wavelengths, where they were first identified nearly two decades ago by the Submillimeter Common-User Bolometer Array (SCUBA) camera on the James Clerk Maxwell Telescope in Hawaii.

Toft's team started by constructing the first representative sample of compact elliptical galaxies with accurate sizes and spectroscopic redshifts, or distances, measured with Hubble's Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) and 3D-HST (3D-Hubble Space Telescope) programs. 3D-HST is a near-infrared spectroscopic survey to study the physical processes that shape galaxies in the distant universe. The astronomers combined these data with observations from the Subaru telescope in Hawaii, and Spitzer. This allowed for accurate stellar age estimates, from which they concluded compact elliptical galaxies formed in intense starbursts inside the galaxies that preceded them by as long as two billion years.

Next, the team made the first representative sample of the most distant submillimeter galaxies using COSMOS data from the Hubble, Spitzer and Herschel space telescopes, and ground-based telescopes such as Subaru, the James Clerk Maxwell Telescope, and the Submillimeter Array, all located in Hawaii. This multi-spectral information, stretching from optical light through submillimeter wavelengths, yielded a full suite of information about the sizes, stellar masses, star-formation rates, dust content, and precise distances of the dust-enshrouded galaxies that were present early in the universe.

When Toft's team compared the samples of the two galaxy populations, it discovered an evolutionary link between the compact elliptical galaxies and the submillimeter galaxies. The observations show that the violent starbursts in the dusty galaxies had the same characteristics that would have been predicted for progenitors to the compact elliptical galaxies. Toft's team also calculated the intense starburst activity inside the submillimeter galaxies lasted only about 40 million years before the interstellar gas supply was exhausted.

The results appear in the Jan. 29 online issue of The Astrophysical Journal. For related and high resolution imagery, visit: http://hubblesite.org/news/2014/10.

Image credit: NASA, ESA, S. Toft (Niels Bohr Institute), and A. Feild (STScI)

Saturday, February 1, 2014

Star Formation in Messier 20, the Trifid Nebula


A storm of stars is brewing in the Trifid nebula, as seen in this view from NASA's Wide-field Infrared Survey Explorer, or WISE. The stellar nursery, where baby stars are bursting into being, is the yellow-and-orange object dominating the picture. Yellow bars in the nebula appear to cut a cavity into three sections, hence the name Trifid nebula.

Colors in this image represent different wavelengths of infrared light detected by WISE. The main green cloud is made up of hydrogen gas. Within this cloud is the Trifid nebula, where radiation and winds from massive stars have blown a cavity into the surrounding dust and gas, and presumably triggered the birth of new generations of stars. Dust glows in infrared light, so the three lines that make up the Trifid, while appearing dark in visible-light views, are bright when seen by WISE.

The blue stars scattered around the picture are older, and they lie between Earth and the Trifid nebula. The baby stars in the Trifid will eventually look similar to those foreground stars. The red cloud at upper right is gas heated by a group of very young stars.

The Trifid nebula is located 5,400 light-years away in the constellation Sagittarius.

Blue represents light emitted at 3.4-micron wavelengths, and cyan (blue-green) represents 4.6 microns, both of which come mainly from hot stars. Relatively cooler objects, such as the dust of the nebula, appear green and red. Green represents 12-micron light and red, 22-micron light.

Image credit: NASA/JPL-Caltech/UCLA

Note: For more information, see Where the Wild Stars Are.