This artist's impression shows the distant dwarf planet Eris. New observations have shown that Eris is smaller than previously thought and almost exactly the same size as Pluto. Eris is extremely reflective and its surface is probably covered in frost formed from the frozen remains of its atmosphere.
Astronomers have used a large survey to test a prediction that close encounters between galaxies can trigger the rapid growth of supermassive black holes. Key to this work was Chandra's unique ability to pinpoint actively growing black holes through the X-rays they generate.
The researchers looked at 562 pairs of galaxies ranging in distances from about 3 billion to 8 billion light years from Earth. They found that the galaxies in the early stages of an encounter with another were more likely than isolated, or "lonelier" galaxies to have actively growing black holes in their cores.
These two composite images show a sample of the pairs of galaxies that are undergoing close encounters in the survey. In these images, the data from NASA's Chandra X-ray Observatory are shown in purple and Hubble Space Telescope data are in gold. In both images, the point-like X-ray source near the center is generated by gas that has been heated to millions of degrees as it falls toward a supermassive black hole located in the middle of its host galaxy. The other faint X-ray emission may be caused by hot gas associated with the pair of galaxies.
The authors of the study estimate that nearly one-fifth of all moderately active black holes are found in galaxies undergoing the early stages of an interaction. This leaves open the question of what events are responsible for fueling the remaining 80% of growing black holes. Some of these may involve the late stages of mergers between two galaxies. Less violent events such as gas falling in from the halo of the galaxy, or the disruption of small satellite galaxies are also likely to play an important role.
The survey used in this research is called the Cosmic Evolution Survey (COSMOS), which covers two square degrees on the sky with observations from several major space-based observatories including Chandra and Hubble. Accurate distance information about the galaxies was also derived from optical observations with the European Southern Observatory's Very Large Telescope. The researchers compared a sample of 562 galaxies in pairs with 2726 solo galaxies to come to their conclusions.
In visible light, the star-forming cloud cataloged as NGC 281 in the constellation of Cassiopeia appears to be chomping through the cosmos, earning it the nickname the "Pacman" nebula after the famous Pac-Man video game of the 1980s. However, the Wide-field Infrared Survey Explorer, or WISE, observed the nebula in infrared light, revealing a different view.
NGC 281 is a giant cloud of dust and gas located about 9,200 light-years away within our own Milky Way galaxy, and spans about 130 light-years in space. Inside the cloud, a new cluster of stars is forming. This young cluster, called IC 1590, appears as a group of stars near the center of the red and green cloud in the upper portion of the image. Within the cluster there are several very massive stars, many times the mass of the sun. These stars are also very hot and produce large amounts of ultraviolet radiation and blow strong winds. The radiation and winds erode the larger cloud from the inside out, giving it a shell-like appearance. The winds and radiation heat the dust in the cloud, which then glows in infrared light. The wavelengths at which the dust glows depends on the temperatures.
The process of the erosion of the nebula by the young star cluster is thought to trigger the additional formation of stars. Around the edges of NGC 281 are many long columns pointing toward the central star cluster, giving the appearance of the Pacman with teeth. These are parts of the cloud that are a bit more dense, and hence erode more slowly than the rest of the cloud. At the tips of these columns, the material may be compressed enough to set off the formation of new stars. Also, sprinkled around the images are several star-like objects that appear very red. These are likely baby stars in the early stages of formation. They are wrapped in cocoons of dust, which glow strongly in the longer wavelengths, giving them their red color in this image.
This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily from stars, the hottest objects pictured. Green and red represent light at 12 and 22 microns, which is primarily from warm dust (with the green dust being warmer than the red dust).
These Dawn FC (framing camera) composite images show the spectacular spectral diversity of Vesta's surface. The FC has 7 color filters which allow it to image Vesta in a number of different wavelengths of light. Being able to image in many wavelengths enhances features and colors that would otherwise be indistinguishable to the human eye. The left image shows a RGB color composite image of Vesta. RGB stands for red, green and blue and in this case red is the 750nm filter, green is the 920nm filter and blue is the 980nm filter. Nm stands for nanometers and is a measure of the wavelength of light. The images from these 3 filters were combined into this one RGB composite image, which enhances Vesta's coloration. The right image is also a RGB composite image. This time red is the ratio of the brightness at a wavelength of 750nm to the brightness at 440nm; green is used for the ratio of the brightness at 750nm to 920nm and blue is used for the ratio of the brightness at 440nm to 750nm. These ratios have all been picked for specific scientific purposes. The green shows the relative strength of a particular mineralogical characteristic, the ferrous absorption band, at 1000nm so that a brighter green color signifies a higher relative strength of this band. The blending between the red and blue heightens the color range of visible light.
This image combines data from four different space telescopes to create a multi-wavelength view of all that remains of the oldest documented example of a supernova, called RCW 86. The Chinese witnessed the event in 185 A.D., documenting a mysterious "guest star" that remained in the sky for eight months. X-ray images from the European Space Agency's XMM-Newton Observatory and NASA's Chandra X-ray Observatory are combined to form the blue and green colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova.
Infrared data from NASA's Spitzer Space Telescope, as well as NASA's Wide-Field Infrared Survey Explorer (WISE) are shown in yellow and red, and reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.
By studying the X-ray and infrared data together, astronomers were able to determine that the cause of the explosion witnessed nearly 2,000 years ago was a Type Ia supernova, in which an otherwise-stable white dwarf, or dead star, was pushed beyond the brink of stability when a companion star dumped material onto it. Furthermore, scientists used the data to solve another mystery surrounding the remnant -- how it got to be so large in such a short amount of time. By blowing a wind prior to exploding, the white dwarf was able to clear out a huge "cavity," a region of very low-density surrounding the system. The explosion into this cavity was able to expand much faster than it otherwise would have.
This is the first time that this type of cavity has been seen around a white dwarf system prior to explosion. Scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.
RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that is slightly larger than the full moon.
NASA's MESSENGER spacecraft has discovered strange hollows on the surface of Mercury. Images taken from orbit reveal thousands of peculiar depressions at a variety of longitudes and latitudes, ranging in size from 60 feet to over a mile across and 60 to 120 feet deep. No one knows how they got there.
"These hollows were a major surprise," says David Blewett, science team member from the Johns Hopkins University Applied Physics Laboratory. "We've been thinking of Mercury as a relic – a place that's really not changing much anymore, except by impact cratering. But the hollows appear to be younger than the craters in which they are found, and that means Mercury's surface is still evolving in a surprising way."
Mars Reconnaissance Orbiter spotted similar depressions in the carbon dioxide ice at Mars' south pole, giving that surface a "swiss cheese" appearance. But on Mercury they're found in rock and often have bright interiors and halos.
"We've never seen anything quite like this on a rocky surface."
If you could stand in one of these "sleepy" hollows on Mercury's surface, you'd find yourself, like Ichabod Crane, in a quiet, still, haunting place, with a black sky above your head.
"There's essentially no atmosphere on Mercury," explains Blewett. "And with no atmosphere, wind doesn't blow and rain doesn't fall. So the hollows weren't carved by wind or water. Other forces must be at work."
As the planet closest to the Sun, Mercury is exposed to fierce heat and extreme space weather. Blewett believes these factors play a role.
A key clue, he says, is that many of the hollows are associated with central mounds or mountains inside Mercury's impact craters. These so-called “peak rings” are thought to be made of material forced up from the depths by the impact that formed the crater. Excavated material could be unstable when it finds itself suddenly exposed at Mercury's surface.
"Certain minerals, for example those that contain sulfur and other volatiles, would be easily vaporized by the onslaught of heat, solar wind, and micrometeoroids that Mercury experiences on a daily basis," he says. "Perhaps sulfur is vaporizing, leaving just the other minerals, and therefore weakening the rock and making it spongier. Then the rock would crumble and erode more readily, forming these depressions."
MESSENGER has indeed proven Mercury unexpectedly rich in sulfur. That in itself is a surprise that's forcing scientists to rethink how Mercury was formed. The prevailing models suggest that either (1) very early in Solar System history, during the final sweep-up of the large planetesimals that formed the planets, a colossal impact tore off much of Mercury's rocky outer layering; or (2) a hot phase of the early Sun heated up the surface enough to scorch off the outer layers. In either case, the elements with a low boiling point – volatiles like sulfur and potassium – would have been driven off.
But they're still there.
"The old models just don't fit with the new data, so we'll have to look at other hypotheses."
To figure out how the planets and Solar System came to be, scientists must understand Mercury.
"It's the anchor at one end of the Solar System. Learning how Mercury formed will have major implications for the rest of the planets. And MESSENGER is showing that, up to now, we've been completely wrong about this little world in so many ways!"
What other surprises does Mercury hold? The sleepy hollows of the innermost planet may be just the beginning.
HiRISE observations like this one are used to aid in classification and volume estimates of dunes in the USGS global dune database.
Sand dunes are among the most widespread aeolian features present on Mars. Their spatial distribution and morphology are sensitive to subtle shifts in wind circulation patterns and wind strengths. These provide clues to the sedimentary history of the surrounding terrain.
What's fascinating about this image is the ridges running the length of the dunes here, creating the spectacular illusion that we're looking at millipedes. This is a good example of what's called "pareidolia," where we see things that really are not there.
Luckily, the power of HiRISE helps us see formations in greater detail to know we're seeing impressive dune ridge formations and not insects!
The Bolshoi simulation is the most accurate cosmological simulation of the evolution of the large-scale structure of the universe yet made (“bolshoi” is the Russian word for “great” or “grand”). The first two of a series of research papers describing Bolshoi and its implications have been accepted for publication in the Astrophysical Journal. The first data release of Bolshoi outputs, including output from Bolshoi and also the BigBolshoi or MultiDark simulation of a volume 64 times bigger than Bolshoi, has just been made publicly available to the world’s astronomers and astrophysicists.
The starting point for Bolshoi was the best ground- and space-based observations, including NASA’s long-running and highly successful WMAP Explorer mission that has been mapping the light of the Big Bang in the entire sky. One of the world's fastest supercomputers then calculated the evolution of a typical region of the universe a billion light years across. The Bolshoi simulation took 6 million cpu hours to run on the Pleiades supercomputer—recently ranked as seventh fastest of the world’s top 500 supercomputers—at NASA Ames Research Center.
Large cosmological simulations such as the Millennium simulation are now the basis for much current research on the structure of the universe and the evolution of galaxies and clusters of galaxies. Due to significant advances in the measurement of the cosmological parameters and in the power and speed of supercomputers and simulation codes over the past half-decade since the Millennium cosmological simulation, the Bolshoi simulation is substantially better in resolution and accuracy. The Principal Investigators of the Bolshoi project, Anatoly Klypin and Joel Primack, and their colleagues anticipate that Bolshoi will become cosmology’s new benchmark simulation for making theoretical predictions that can then be tested against data gathered by observational astronomers. One of the first such predictions was the fraction of Milky Way-type galaxies with satellite galaxies as bright as our galaxy's Large and Small Magellanic Clouds; the results were in excellent agreement with observations from the Sloan Digital Sky Survey.
This artist's concept illustrates an icy planet-forming disk around a young star called TW Hydrae, located about 175 light-years away in the Hydra, or Sea Serpent, constellation. Astronomers using the Herschel Space Observatory detected copious amounts of cool water vapor, illustrated in blue, emanating from the star's planet-forming disk of dust and gas. The water vapor, which probably comes from icy grains in the disk, is located in the frigid outer regions of the star system, where comets will take shape.
In our own solar system, comets are thought to have carried water to Earth, creating our oceans. A similar process might be taking place around TW Hydrae -- comets could, over the next several millions of years, transport water to young worlds. The Herschel results demonstrate that vast reservoirs of water are available around stars for creating these hypothetical water worlds.
The graph of data (Figure 1) from Herschel shows how the cool water vapor was detected. Water molecules come in two "spin" forms, called ortho and para, in which the two spins of the hydrogen nuclei have different orientations. In this case, the team compared the ratio of ortho to para water seen in the TW Hydrae disk to that in comets, and found very low values. Lower ratios indicate cooler temperatures, though in practice the analysis is much more complicated. This is the first demonstration that water exists in large quantities in the frigid, outer regions of solar systems, where comets take shape.
This artist's conception illustrates a storm of comets around a star near our own, called Eta Corvi. Evidence for this barrage comes from NASA's Spitzer Space Telescope, whose infrared detectors picked up indications that one or more comets was recently torn to shreds after colliding with a rocky body. In this artist's conception, one such giant comet is shown smashing into a rocky planet, flinging ice- and carbon-rich dust into space, while also smashing water and organics into the surface of the planet. A glowing red flash captures the moment of impact on the planet. Yellow-white Eta Corvi is shown to the left, with still more comets streaming toward it.
Spitzer detected spectral signatures of water ice, organics and rock around Eta Corvi -- key ingredients of comets. This is the first time that evidence for such a comet storm has been seen around another star. Eta Corvi is just about the right age, about one billion years old, to be experiencing a bombardment of comets akin to what occurred in our own solar system at 600 to 800 millions years of age, termed the Late Heavy Bombardment.
Scientists say the Late Heavy Bombardment was triggered in our solar system by the migration of our outer planets, which jostled icy comets about, sending some of them flying inward. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life.
This image from VISTA is a tiny part of the VISTA Variables in the Via Lactea (VVV) survey that is systematically studying the central parts of the Milky Way in infrared light. On the right lies the globular star cluster UKS 1 and on the left lies a much less conspicuous new discovery, VVV CL001 — a previously unknown globular, one of just 160 known globular clusters in the Milky Way at the time of writing. The new globular appears as a faint grouping of stars about 25% of the width of the image from the left edge, and about 60% of the way from bottom to top.
NASA's Fermi team recently released the second catalog of gamma-ray sources detected by their satellite's Large Area Telescope (LAT). Of the 1873 sources found, nearly 600 are complete mysteries. No one knows what they are.
"Fermi sees gamma rays coming from directions in the sky where there are no obvious objects likely to produce gamma rays," says David Thompson, Fermi Deputy Project Scientist from Goddard Space Flight Center.
Gamma rays are by their very nature heralds of great energy and violence. They are a super-energetic form of light produced by sources such as black holes and massive exploding stars. Gamma-rays are so energetic that ordinary lenses and mirrors do not work. As a result, gamma-ray telescopes can't always get a sharp enough focus to determine exactly where the sources are.
For two thirds of the new catalog's sources the Fermi scientists can, with at least reasonable certainty, locate a known gamma ray-producing object*, such as a pulsar or blazar, in the vicinity the gamma-rays are coming from. But the remaining third – the "mystery sources" -- have the researchers stumped, at least for now. And they are the most tantalizing.
"Some of the mystery sources could be clouds of dark matter – something that's never been seen before," speculates Thompson.
About 85% of the gravitational mass of the universe is dark matter. The stuff we see makes up the rest. Dark matter is something that pulls on things with the force of its gravity but can't be detected in any other way. It doesn't shine – doesn't emit or scatter light – hence the adjective "dark."
Astronomers cannot detect dark matter directly using optical or radio telescopes. But dark matter just might shine in gamma rays.
"We've been using Fermi to search for dark matter for a long time," says the principal investigator for the Large Area Telescope, Peter Michelson of Stanford University.
Some researchers believe that when two dark matter antiparticles bump into each other, they will annihilate, producing gamma rays. Concentrated clouds of dark matter could form a gamma ray source at specific wavelengths detectable by Fermi.
"If we see a bump in the gamma-ray spectrum -- a narrow spectral line at high energies corresponding to the energy of the annihilating particles – we could be the first to 'apprehend' dark matter,” says Michelson.
The team plans to continue observing the mystery sources. Fermi scans the entire sky ever three hours, and this ongoing sequence of observations "piles up" gamma rays for the researchers to analyze. So far, too few gamma rays have been collected from the mystery sources to form definite conclusions.
Another, less-dark possibility for some of the mystery sources is colliding galaxy clusters. According to Michelson and Thompson, clashes of such magnitude would generate super large scale shock waves that would accelerate particles. Others of the sources, they say, might be some brand new phenomenon, perhaps something involving galactic black holes.
When all is said and done, many of the mystery sources could prove to be familiar. "[They] will probably turn out to be members of known source classes – things we know but haven't recognized yet, like undiscovered pulsars, binary systems, and supernova remnants," says Michelson.
"Of course we're hoping for something really exotic like dark matter, but we have to look first at all the other options," says Thompson. "Fermi is an ongoing mission. We'll continue to search for answers to these puzzles and perhaps turn up even more surprises."
Will notorious dark matter finally be nabbed? Stay tuned!
Footnote: *Among the known classes in the second Fermi LAT catalog are almost 100 gamma-ray pulsars -- super dense neutron stars that are blinking in gamma rays. They are 1 ½ times the mass of our sun, but crushed to the size of a city. "Pulsars rotate rapidly and the light from them sweeps past us like light from a light house," explains Thompson. "Some of them rotate as fast as a kitchen blender -- hundreds of times per second!" The LAT team has rock-solid identification on 83 pulsars in our own galaxy. But the largest single class of gamma-ray sources the LAT "sees" is blazars from active galactic nuclei. Blazars make up over 1000 of the 1873 sources. "They are of course extra-galactic," says Michelson. "Only about 25 of these are rock-solid identifications, but we believe the others, because of their location, are likely associated with active galactic nuclei blazars too." Active galactic nuclei are the cores of galaxies. "The gamma rays are probably coming from the vicinity of black holes, which have 1 million to 1 billion times the mass of our sun," says Thompson. "A black hole pulls everything into itself by virtue of its unbelievable strong gravity. As it does so, enormous energy is released and squirted away from the black hole as a beam of particles and radiation moving at nearly the speed of light. It's called a blazar if the jet is aimed at us and we are looking down the barrel. But the jet of energy doesn't come out of the black hole itself; rather it is powered by material falling into the black hole." Binary systems constitute another known source class in the new catalog. They are made up of a neutron star or black hole orbiting a large normal star.
Arguably one of America's most magnificent national parks is the Grand Canyon in northern Arizona. The Advanced Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft captured this 3-D view on July 14, 2011, created by draping the ASTER image over a Digital Elevation Model produced from ASTER stereo data. In this perspective view looking to the northeast, the buildings and roads in the center foreground are Grand Canyon Village. The Bright Angel Trail can be seen descending 3,000 feet (914 meters) to Indian Garden, before continuing to the Colorado River far below. Completing the 25-mile (40-kilometer) rim-to-rim hike takes the hiker to the North Rim and the North Rim Lodge. The ASTER image is located near 36 degrees north latitude, 112.1 degrees west longitude.
The Advanced Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft provided this spacebird's-eye view of the eastern part of Grand Canyon National Park in northern Arizona in this image, acquired July 14, 2011. In this perspective view looking to the west, the tourist facilities of Grand Canyon Village are visible in the upper left. The higher-elevation North Rim is seen on the right. The canyon is up to 9 miles (14.5 kilometers) wide and 5,600 feet (1,707 meters) deep, attesting to the power of moving water to carve Earth's surface. This 3-D view was created by draping the ASTER image over a Digital Elevation Model produced from ASTER stereo data .The ASTER image is located near 36 degrees north latitude, 112.1 degrees west longitude.
The first released VST image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This vast region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across the entire image. The data were processed using the Astro-WISE software system developed by E.A. Valentijn and collaborators at Groningen and elsewhere.
This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J1206. Galaxy clusters like these have enormous mass, and their gravity is powerful enough to visibly bend the path of light, somewhat like a magnifying glass.
These so-called lensing clusters are useful tools for studying very distant objects, because this lens-like behavior amplifies the light from faraway galaxies in the background. They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime and the expansion of the cosmos.
This is one of 25 clusters being studied as part of the CLASH (Cluster Lensing and Supernova survey with Hubble) program, a major project to build a library of scientific data on lensing clusters.
G299.2-2.9 is an intriguing supernova remnant found about 16,000 light years away in the Milky Way galaxy. Evidence points to G299.2-2.9 being the remains of a Type Ia supernova, where a white dwarf has grown sufficiently massive to cause a thermonuclear explosion. Because it is older than most supernova remnants caused by these explosions, at an age of about 4,500 years, G299.2-2.9 provides astronomers with an excellent opportunity to study how these objects evolve over time. It also provides a probe of the Type Ia supernova explosion that produced this structure.
This composite image shows G299.2-2.9 in X-ray light from Chandra, along with data from the ROSAT satellite (orange), that has been overlaid on an infrared image from the Two Micron All-Sky Survey (2MASS). The faint X-ray emission from the inner region reveals relatively large amounts of iron and silicon, as expected for a remnant of a Type Ia supernova. The outer shell of the remnant is complex, with at least a double shell structure. Typically, such a complex outer shell is associated with a star that has exploded into space where gas and dust are not uniformly distributed.
Since most theories to explain Type Ia supernovas assume they go off in a uniform environment, detailed studies of this complicated outer shell should help astronomers improve their understanding of the environments where these explosions occur. It is very important to understand the details of Type Ia explosions because astronomers use them as cosmic mile markers to measure the accelerated expansion of the universe and study dark energy. The discovery of this accelerated expansion in the late 1990s led to the recent award of the Nobel Prize in Physics.
This color-composite image of the Helix Nebula (NGC 7293) was created from images obtained using the the Wide Field Imager (WFI), an astronomical camera attached to the 2.2-meter Max-Planck Society/ESO telescope at the La Silla observatory in Chile. The blue-green glow in the center of the Helix comes from oxygen atoms shining under effects of the intense ultraviolet radiation of the 120,000 degree Celsius central star and the hot gas. Further out from the star and beyond the ring of knots, the red color from hydrogen and nitrogen is more prominent. A careful look at the central part of this object reveals not only the knots, but also many remote galaxies seen right through the thinly spread glowing gas.
This image was created from images through blue, green and red filters and the total exposure times were 12 minutes, 9 minutes and 7 minutes respectively.
This image of the asteroid Vesta, calculated from a shape model, shows a tilted view of the topography of the south polar region. The image has a resolution of about 1,000 feet (300 meters) per pixel, and the vertical scale is 1.5 times that of the horizontal scale.
This perspective shows the topography, but removes the overall curvature of Vesta, as if the giant asteroid were flat and not rounded. An observer on Vesta would not have a view like this, because the distant features would disappear over the curvature of the horizon. (In the same way, if you were standing in North America, you would not be able to see a tall Mt. Everest in the distance, because of Earth's curvature.)
This artist’s impression shows galaxies at a time less than a billion years after the Big Bang, when the Universe was still partially filled with hydrogen fog that absorbed ultraviolet light. New observations with the ESO Very Large Telescope are probing this important phase of the early Universe by studying the light from some of the most distant galaxies ever detected.
This false-color map of the giant asteroid Vesta was created from stereo images obtained by the framing camera aboard NASA's Dawn spacecraft. The image shows the elevation of surface structures with a horizontal resolution of about 750 meters per pixel.
The terrain model of Vesta's southern hemisphere shows a big circular structure with a diameter of about 300 miles (500 kilometers), its rim rising above the interior of the structure for more than 9 miles (15 kilometers.) From low-resolution images of the Hubble Space Telescope it was known that a big depression existed at Vesta's south pole, suggestive of being a big impact basin. Scientists on the Dawn team are still investigating the processes that formed this structure.
This artist's concept illustrates what the flaring black hole called GX 339-4 might look like. Infrared observations from NASA's Wide-field Infrared Survey Explorer (WISE) reveal the best information yet on the chaotic and extreme environments of this black hole's jets.
GX 339-4 likely formed from a star that exploded. It is surrounded by an accretion disk (red) of material being pulled onto the black hole from a neighboring star (yellow orb). Some of this material is shot away in the form of jets (yellow flows above and below the disk). The region close in to the black hole glows brightly in infrared light.
This graphic contains an image and illustration of a nearby star, named CoRoT-2a, which has a planet in close orbit around it. The separation between the star and planet is only about 3 percent of the distance between the Earth and the Sun, causing some exotic effects not seen in our solar system.
The planet-hosting star is located in the center of the image. Data from NASA's Chandra X-ray Observatory are shown in purple, along with optical and infrared data from the Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT) and the Two Micron All Sky Survey (2MASS). CoRoT-2a is surrounded by a purple glow showing that it is an X-ray source.
This star is pummeling its companion planet -- not visible in this image -- with a barrage of X-rays a hundred thousand times more intense than the Earth receives from the Sun. Data from Chandra suggest that high-energy radiation from CoRoT-2a is evaporating about 5 million tons of matter from the nearby planet every second, giving insight into the difficult survival path for some planets. The artist's representation shows the material, in blue, being stripped off the planet.
The Chandra observations provide evidence that CoRoT-2a is a very active star, with bright X-ray emission produced by powerful, turbulent magnetic fields. This magnetic activity is represented by the prominences and eruptions on the surface of the star in the illustration.
Such strong activity is usually found in much younger stars and may be caused by the proximity of the planet. The planet may be speeding up the star's rotation, causing its magnetic fields to remain active longer than expected. Support for this idea comes from observations of a likely companion star to CoRoT-2a that orbits at a distance about a thousand times greater than the distance between the Earth and the Sun. This star is visible in the image as the faint, nearby star located below and to the right of CoRoT-2a. It is also shown as the bright background star in the illustration. This star is not detected in X-rays, perhaps because it does not have a close-in planet like CoRoT-2b to cause it to stay active.
The planet, CoRoT-2b, was discovered by the French Space Agency's Convection, Rotation and planetary Transits (CoRoT) satellite in 2008. It is located about 880 light years from Earth and has a mass about 3 time that of Jupiter.
After its first Mercury solar day (176 Earth days) in orbit, MESSENGER has nearly completed two of its main global imaging campaigns: a monochrome map at 250 m/pixel and an eight-color, 1-km/pixel color map. Apart from small gaps, which will be filled in during the next solar day, these global maps now provide uniform lighting conditions ideal for assessing the form of Mercury's surface features as well as the color and compositional variations across the planet. The orthographic views seen here, centered at 75° E longitude, are each mosaics of thousands of individual images. At right, images taken through the wide-angle camera filters at 1000, 750, and 430 nm wavelength are displayed in red, green, and blue, respectively.
New measurements from the Herschel Space Observatory have discovered water with the same chemical signature as our oceans in a comet called Hartley 2 (pictured at right). Previously, astronomers thought icy comets impacting on a young Earth had deposited only about 10 percent of the water comprising our oceans. The new findings, however, suggest that comets played a much bigger role.
The image of Comet Hartley 2 at top right was taken by NASA's EPOXI mission. The image at bottom right is an artist's concept of a comet.
Using the Herschel Space Observatory, astronomers have discovered that Comet Hartley 2 possesses a ratio of "heavy water" to light, or normal, water that matches what's found in Earth's oceans. In heavy water, one of the two hydrogen atoms has been replaced by the heavy hydrogen isotope known as deuterium. Hartley 2 contains half as much heavy water as other comets analyzed to date. Herschel's "Heterodyne Instrument for the Far Infrared," or HIFI, was used to obtain the spectral signatures of the water molecules, as shown here in the graphs.
The image of Comet Harley 2 was taken by NASA's EPOXI mission.
At the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center in Florida, the Mars Science Laboratory rover, Curiosity, and the spacecraft's descent stage have been enclosed inside the spacecraft's aeroshell.
This image, taken October 1, 2011, shows the aeroshell with its heat shield on top.
The heat shield and the spacecraft's back shell together form the encapsulating aeroshell that will protect the rover from the intense heat that will be generated as the flight system descends through the Martian atmosphere.
The mission is on track for launch from Cape Canaveral Air Force Station during the period from November 25 to December 18, 2011.
