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| Piú viste - The Universe in Super Definition |
NGC-1333-PIA09965.jpgWater Vapor inside NGC 133358 visiteThis plot of infrared data, called a Spectrum, shows the strong signature of water vapor deep within the core of an Embryonic Star System called NGC 1333-IRAS 4B.
The data were captured by NASA's SST using an instrument called Spectrograph.
A spectrograph collects light and sorts it according to color, or wavelength. In this case, infrared light from NGC 1333-IRAS 4B was broken up into the wavelengths listed on the horizontal axis of the plot. The sharp spikes, called spectral lines, occur at wavelengths at which the stellar object is particularly bright. The signature of water vapor is revealed in the pattern of wavelengths at which the spikes appear.
By comparing the observed data to a model (lower curve), astronomers can also determine the physical and chemical details of the region.
F.e.: Astronomers say these data suggest that ice in a cocoon surrounding the forming star is falling inward. The ice then smacks supersonically into a dusty planet-forming disk surrounding the stellar embryo, heats up and vaporizes quickly, releasing the infrared light that Spitzer collected.
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Abell-1763-PIA10227.jpgCelestial Cities and the Roads that connect Them58 visiteThis is a representation of galaxies in and surrounding a galaxy cluster called Abell 1763. The placement of each dot is based on the actual coordinates of galaxies in the region. Blue dots are active star-forming galaxies; red dots show galaxies that are not actively forming stars.
Galaxies across the universe reside in cosmic communities big and small. Large, densely populated galactic communities are called galaxy clusters (highlighted in the orange circle). Like cities on Earth, galaxy clusters are scattered throughout the universe and are connected by a web of dusty highways called filaments (highlighted in purple). Smaller galactic communities are sprinkled along the filaments, creating celestial suburbs.
Over time, astronomers suspect that all galactic suburbanites make their way to a galaxy cluster by way of filaments. Observations from NASA's Spitzer Space Telescope show that filamentary galaxies form stars at twice the rate of their densely clustered counterparts.
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.
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PIA03243.jpgThe way we were...57 visiteThis artist's concept illustrates a solar system that is a much younger version of our own. Dusty disks, like the one shown here circling the star, are thought to be the breeding grounds of planets, including rocky ones like Earth. Astronomers using NASA's Spitzer Space Telescope spotted some of the raw ingredients for DNA and protein in one such disk belonging to a star called IRS 46. The ingredients, gaseous precursors to DNA and protein called acetylene and hydrogen cyanide, were detected in the star's inner disk, the region where scientists believe Earth-like planets would be most likely to form.
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M 42-PIA08653.jpgMoments of M-4257 visiteThis infrared image from NASA's Spitzer Space Telescope shows the Orion nebula, our closest massive star-making factory, 1,450 light-years from Earth. The nebula is close enough to appear to the naked eye as a fuzzy star in the sword of the popular hunter constellation.
The nebula itself is located on the lower half of the image, surrounded by a ring of dust. It formed in a cold cloud of gas and dust and contains about 1,000 young stars. These stars illuminate the cloud, creating the beautiful nebulosity, or swirls of material, seen here in infrared.
In the center of the nebula (bottom inset of figure 1) are four monstrously massive stars, up to 100,000 times as luminous as our sun, called the Trapezium (tiny yellow smudge to the lower left of green splotches. Radiation and winds from these stars are blasting gas and dust away, excavating a cavity walled in by the large ring of dust.
Behind the Trapezium, still buried deeply in the cloud, a second generation of massive stars is forming (in the area with green splotches). The speckled green fuzz in this bright region is created when bullets of gas shoot out from the juvenile stars and ram into the surrounding cloud.
Above this region of intense activity are networks of cold material that appear as dark veins against the pinkish nebulosity (upper inset pf figure 1). These dark veins contain embryonic stars. Some of the natal stars illuminate the cloud, creating small, aqua-colored wisps. In addition, jets of gas from the stars ram into the cloud, resulting in the green horseshoe-shaped globs.
Spitzer surveyed a significant swath of the Orion constellation, beyond what is highlighted in this image. Within that region, called the Orion cloud complex, the telescope found 2,300 stars circled by disks of planet-forming dust and 200 stellar embryos too young to have developed disks.
This image shows infrared light captured by Spitzer's infrared array camera. Light with wavelengths of 8 and 5.8 microns (red and orange) comes mainly from dust that has been heated by starlight. Light of 4.5 microns (green) shows hot gas and dust; and light of 3.6 microns (blue) is from starlight.
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AlienWorld-PIA09228.jpgTwin Suns' Sunset57 visiteOur solitary sunsets here on Earth might not be all that common in the grand scheme of things. New observations from NASA's Spitzer Space Telescope have revealed that mature planetary systems -- dusty disks of asteroids, comets and possibly planets -- are more frequent around close-knit twin, or binary, stars than single stars like our sun. That means sunsets like the one portrayed in this artist's photo concept, and more famously in the movie "Star Wars," might be quite commonplace in the universe.
Binary and multiple-star systems are about twice as abundant as single-star systems in our galaxy, and, in theory, other galaxies. In a typical binary system, two stars of roughly similar masses twirl around each other like pair-figure skaters. In some systems, the two stars are very far apart and barely interact with each other. In other cases, the stellar twins are intricately linked, whipping around each other quickly due to the force of gravity.
Astronomers have discovered dozens of planets that orbit around a single member of a very wide stellar duo. Sunsets from these worlds would look like our own, and the second sun would just look like a bright star in the night sky.
But do planets exist in the tighter systems, where two suns would dip below a planet's horizon one by one? Unveiling planets in these systems is tricky, so astronomers used Spitzer to look for disks of swirling planetary debris instead. These disks are made of asteroids, comets and possibly planets. The rocky material in them bangs together and kicks up dust that Spitzer's infrared eyes can see. Our own solar system is swaddled in a similar type of disk.
Surprisingly, Spitzer found more debris disks around the tightest binaries it studied (about 20 stars) than in a comparable sample of single stars. About 60 percent of the tight binaries had disks, while the single stars only had about 20 percent. These snug binary systems are as close or closer than just three times the distance between Earth and the sun. And the disks in these systems were found to circumnavigate both members of the star pair, rather than just one.
Though follow-up studies are needed, the results could mean that planet formation is more common around extra-tight binary stars than single stars. Since these types of systems would experience double sunsets, the artistic view portrayed here might not be fiction.
The original sunset photo used in this artist's concept was taken by Robert Hurt of the Spitzer Science Center at the California Institute of Technology, Pasadena, Calif.
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The_Evaporating_Planet.jpgWater Claimed in Evaporating Planet HD 209458b57 visitePlanet HD 209458b is evaporating. It is so close to its parent star that its heated atmosphere is simply expanding away into space. Some astronomers studying this distant planetary system now believe they have detected water vapor among the gases being liberated. This controversial claim, if true, would mark the first instance of planetary water beyond our Solar System, and indicate anew that life might be sustainable elsewhere in the universe. HD 209458b is known as a hot Jupiter type system because it involves a Jupiter-type planet in a Mercury-type orbit. Although spectroscopic observations from the Hubble Space Telescope are the basis for the water detection claim, the planetary system is too small and faint to image. Therefore, an artist's impression of the HD 209458b system is shown above. Research into the atmospheric composition of HD 209458b and other extrasolar planets is continuing.MareKromium
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NGC-0404-PIA11393-1.jpgNGC 404 - The 'Ghost of Mirach' rears its Spooky Head57 visiteThe "Ghost of Mirach" Galaxy is shown in visible light on the left, and in UltraViolet as seen by NASA's Galaxy Evolution Explorer on the right. The fields of view are identical in both pictures, with the Ghost of Mirach — a galaxy also known as NGC 404 — seen as the whitish spot in the center of the images.
Mirach is a Red Giant star that looms large in visible light. Because NGC 404 is lost in the glare of this star, it was nicknamed the "Ghost of Mirach".
But when the galaxy is viewed in ultraviolet light, it comes to "life", revealing a never-before-seen ring. This ring, seen in blue in the picture on the right, contains new stars — a surprise considering that the galaxy was previously thought to be, essentially, dead.
The field of view spans 55.000 Light Years across. The Ghost of Mirach is located 11 MLY from Earth. The star Mirach is very close in comparison — since it is only 200 LY away and is visible with the naked eye.
The visible data come from the Digitized Sky Survey of the Space Telescope Science Institute in Baltimore, Md.MareKromium
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ARP-147.jpgARP 14757 visiteJust a couple of days after the orbiting observatory was brought back online, Hubble aimed its prime working camera, the Wide Field Planetary Camera 2 (WFPC2), at a particularly intriguing target, a pair of Gravitationally Interacting Galaxies called Arp 147.
The image demonstrated that the camera is working exactly as it was before going offline, thereby scoring a "perfect 10" both for performance and beauty.
The two galaxies happen to be oriented so that they appear to mark the number 10. The left-most galaxy, or the "one" in this image, is relatively undisturbed apart from a smooth ring of starlight. It appears nearly on edge to our line of sight. The right-most galaxy, resembling a zero, exhibits a clumpy, blue ring of intense star formation.
The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.
The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.
Arp 147 appears in the Arp Atlas of Peculiar Galaxies, compiled by Halton Arp in the 1960s and published in 1966.
This picture was assembled from WFPC2 images taken with three separate filters. The blue, visible-light, and infrared filters are represented by the colors blue, green, and red, respectively.
The galaxy pair was photographed on October 27-28, 2008. Arp 147 lies in the constellation Cetus, and it is more than 400 MLY away from Earth.MareKromium
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Black Hole-PIA08697_fig1.jpgBlack Holes56 visiteThis diagram illustrates research from NASA's Galaxy Evolution Explorer showing that black holes -- once they reach a critical size -- can put the brakes on new star formation in elliptical galaxies.
In this graph, galaxies and their supermassive black holes are indicated by the drawings (the black circle at the center of each galaxy represents the black hole). The relative masses of the galaxies and their black holes are reflected in the sizes of the drawings. Blue indicates that the galaxy has new stars, while red means the galaxy does not have any detectable new stars.
The Galaxy Evolution Explorer observed the following trend: the biggest galaxies and black holes (shown in upper right corner) are more likely to have no observable star formation (red) than the smaller galaxies with smaller black holes. This is evidence that black holes can create environments unsuitable for stellar birth.
The white line in the diagram illustrates that, for any galaxy no matter what the mass, its black hole must reach a critical size before it can shut down star formation.
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Dark_Matter.jpgBright Universe, Dark Matter56 visiteAn international team of astronomers using NASA's Hubble Space Telescope has created a three-dimensional map that provides the first direct look at the large-scale distribution of dark matter in the universe.
Dark matter is an invisible form of matter that accounts for most of the universe's mass.
The map provides the best evidence yet that normal matter, largely in the form of galaxies, accumulates along the densest concentrations of dark matter. The map reveals a loose network of filaments that grew over time and intersect in massive structures at the locations of clusters of galaxies.
The map stretches halfway back to the beginning of the universe and shows how dark matter has grown increasingly "clumpy" as it collapses under gravity.
This milestone takes astronomers from inference to direct observation of dark matter's influence in the universe. Previous studies of dark matter are based largely on numerical simulations of the expected evolution of large-scale structure. This evolution is driven by the gravitational attraction of dark matter.
Mapping dark matter's distribution in space and time is fundamental to understanding how galaxies grew and clustered over billions of years. Tracing the growth of clustering in the dark matter may eventually also shed light on dark energy, a repulsive form of gravity that influences how dark matter clumps.
The new maps of dark matter and galaxies will provide critical observational underpinnings to future theories for how structure formed in the evolving universe under the relentless pull of gravity. Theories suggest the universe transitioned from a smooth distribution of matter into a sponge-like structure of long filaments.
The research results appeared online today in the journal Nature and were presented at the 209th meeting of the American Astronomical Society in Seattle, Wash., by Richard Massey for the dark matter and Nick Scoville for the galaxies. Both researchers are from the California Institute of Technology, Pasadena, Calif.
"It's reassuring how well our map confirms the standard theories for structure formation." said Massey. He calls dark matter the "scaffolding" inside of which stars and galaxies have been assembled over billions of years.
Researchers created the map using Hubble's largest survey of the universe, the Cosmic Evolution Survey ("COSMOS") with an international team of 70 astronomers led by Scoville. The COSMOS survey covers a sufficiently wide area of sky – nine times the area of the Earth's Moon. This allows for the large-scale filamentary structure of dark matter to be evident. To add 3-D distance information, the Hubble observations were combined with multicolor data from powerful ground-based telescopes. "The 3-D information is vital to studying the evolution of the structures over cosmic time," said Jason Rhodes, a collaborator in the study at the Jet Propulsion Laboratory in Pasadena, Calif.
The dark matter map was constructed by measuring the shapes of half a million faraway galaxies. To reach us, the galaxies' light has traveled through intervening dark matter. The dark matter deflected the light slightly as it traveled through space. Researchers used the observed, subtle distortion of the galaxies' shapes to reconstruct the distribution of intervening mass along Hubble's line of sight — a method called weak gravitational lensing. This effect is analogous to deducing the rippling pattern in a glass shower door by measuring how light from behind it is distorted as it passes through the glass.
"Although this technique has been employed previously, the depth of the COSMOS image and its superior resolution enables a more precise and detailed map, covering a large enough area to see the extended filamentary structures," said co-investigator Richard Ellis of the California Institute of Technology.
For astronomers, the challenge of mapping the universe has been similar to mapping a city from nighttime aerial snapshots showing only streetlights. Dark matter is invisible, so only the luminous galaxies can be seen directly. The new images are equivalent to seeing a city, its suburbs and country roads — in daylight, for the first time. Major arteries and intersections become evident, and a variety of neighborhoods are revealed.
A separate COSMOS team led by Scoville presented images of the large scale galactic structures in the same area with the dark matter. Galaxies appear in visible light seen with Hubble and in ground-based Subaru telescope images by Yoshiaku Taniguchi and colleagues. The hot gas in the densest galaxy clusters was imaged in X-rays by Gunther Hasinger and colleagues using the European Space Agency's XMM-Newton telescope.
Galaxy structures inside the dark matter scaffolding show clusters of galaxies in the process of assembly. These structures can be traced over more than 80 million light-years in the COSMOS survey – approximately five times the extent of the nearby Virgo galaxy cluster. In the densest early universe structures, many galaxies already have old stellar populations, implying that these galaxies formed first and accumulated the greatest masses in a bottom-up assembly process where smaller galaxies merge to make bigger galaxies — like tributaries converging to form a large river.
The COSMOS survey shows that galaxies with on-going star formation, even to the present epoch, dwell in less populated voids and dark matter filaments. "It is remarkable how the environment on the enormous cosmic scales seen in the dark matter structures can influence the properties of individual stars and galaxies — both the maturity of the stellar populations and the progressive 'downsizing' of star formation to smaller galaxies is clearly dependent on the dark matter environment," said Scoville.
"The comparison is of fundamental importance," said Massey. "Almost all current scientific knowledge concerns only baryonic matter. Now that we have begun to map out where dark matter is, the next challenge is to determine what it is, and specifically its relationship to normal matter."
In making the COSMOS survey, Hubble photographed 575 slightly overlapping views of the universe using the Advanced Camera for Surveys' (ACS) Wide Field Camera onboard Hubble. It took nearly 1,000 hours of observations. Thousands of galaxies' spectra were obtained by using the European Southern Observatory's Very Large Telescope in Chile, and the Subaru telescope in Hawaii. The distances to the galaxies were accurately determined through their spectral redshifts. The distribution of the normal matter was partly determined with the European Space Agency's XMM-Newton telescope.
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LonelyPlanet-PIA09118.jpgWhat's the weather like over there?56 visiteCaption NASA:"An artist's conception shows a gas-giant planet orbiting very close to its parent star, creating searingly hot conditions on the planet's surface.
New research suggests that for three such planets lying from 50 to 150 light-years from Earth, strong winds thousands of miles per hour mix the atmosphere so that the temperature is relatively uniform from the permanently light side to the permanently dark side.
This illustration represents an infrared view of a planetary system, in which brightness indicates warmer temperatures. For example, the bright band around the equator of the planet denotes warmer temperatures on both the dark and sunlit sides.
The planet's poles, shown in darker colors, would be cooler".MareKromium
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Abell-901_and_902-PM.jpgAbell 901 and 902 Supercluster56 visiteAstronomers are using NASA's Hubble Space Telescope to dissect one of the largest structures in the universe as part of a quest to understand the violent lives of galaxies. Hubble is providing indirect evidence of unseen dark matter tugging on galaxies in the crowded, rough-and-tumble environment of a massive supercluster of hundreds of galaxies.
Dark matter is an invisible form of matter that accounts for most of the universe's mass. Hubble's Advanced Camera for Surveys has mapped the invisible dark matter scaffolding of the supercluster Abell 901/902, as well as the detailed structure of individual galaxies embedded in it.
The images are part of the Space Telescope Abell 901/902 Galaxy Evolution Survey (STAGES), which covers one of the largest patches of sky ever observed by the Hubble telescope. The area surveyed is so wide that it took 80 Hubble images to cover the entire STAGES field. The new work is led by Meghan Gray of the University of Nottingham in the United Kingdom and Catherine Heymans of the University of British Columbia in Vancouver, along with an international team of scientists.
The Hubble study pinpointed four main areas in the supercluster where dark matter has pooled into dense clumps, totaling 100 trillion times the Sun's mass. These areas match the location of hundreds of old galaxies that have experienced a violent history in their passage from the outskirts of the supercluster into these dense regions. These galaxies make up four separate galaxy clusters.
"Thanks to Hubble's Advanced Camera for Surveys, we are detecting for the first time the irregular clumps of dark matter in this supercluster," Heymans said. "We can even see an extension of the dark matter toward a very hot group of galaxies that are emitting X-rays as they fall into the densest cluster core."
The dark matter map was constructed by measuring the distorted shapes of over 60,000 faraway galaxies. To reach Earth, the galaxies' light traveled through the dark matter that surrounds the supercluster galaxies and was bent by the massive gravitational field. Heymans used the observed, subtle distortion of the galaxies' shapes to reconstruct the dark matter distribution in the supercluster using a method called weak gravitational lensing. The dark matter map is 2.5 times sharper than a previous ground-based survey of the supercluster.
"The new map of the underlying dark matter in the supercluster is one key piece of this puzzle," Gray explained. "At the same time we're looking in detail at the galaxies themselves." The survey's broader goal is to understand how galaxies are influenced by the environment in which they live.
On Earth, the pace of quiet country life is vastly different from the hustle of the big city. In the same way, galaxies living lonely isolated lives look very different from those found in the most crowded regions of the universe, like a supercluster. "We've known for a long time that galaxies in crowded environments tend to be older, redder, and rounder than those in the field," Gray said. "Galaxies are continually drawn into larger and larger groups and clusters by the inevitable force of gravity as the universe evolves."
In such busy environments galaxies are subject to a life of violence: high-speed collisions with other galaxies; the stripping away of gas, the fuel supply they use to form new stars; and distortion due to the strong gravitational pull of the underlying invisible dark matter. "Any or all of these effects may play a role in the transformation of galaxies, which is what we're trying to determine," Gray said.
The STAGES survey's simultaneous focus on both the big picture and the details can be likened to studying a big city. "It's as if we're trying to learn everything we can about New York City and New Yorkers," Gray explained. "We're examining large-scale features, like mapping the roads, counting skyscrapers, monitoring traffic. At the same time we're also studying the residents to figure out how the lifestyles of people living downtown differ from those out in the suburbs. But in our case the city is a supercluster, the roads are dark matter, and the people are galaxies."
Further results by other team members support this view. "In the STAGES supercluster we clearly see that transformations are happening in the outskirts of the supercluster, where galaxies are still moving relatively slowly and first feel the influence of the cluster environment," said Christian Wolf, an Advanced Research Fellow at the University of Oxford in the U.K.
Assistant professor Shardha Jogee and graduate student Amanda Heiderman, both of the University of Texas in Austin, concur. "We see more collisions between galaxies in the regions toward which the galaxies are flowing than in the centers of the clusters," Jogee said. "By the time they reach the center, they are moving too fast to collide and merge, but in the outskirts their pace is more leisurely, and they still have time to interact."
The STAGES team also finds that the outer parts of the clusters are where star formation in the galaxies is slowly switching off and where the supermassive black holes at the hearts of the galaxies are most active.
Added Heiderman: "The galaxies at the centers of the clusters may have been there for a long time and have probably finished their transformation. They are now old, round, red, and dead."
The team plans more studies to understand how the supercluster environment is responsible for producing these changes.
Abell 901/902 resides 2.6 billion light-years from Earth and measures more than 16 million light-years across.
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