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| Piú votate - The Universe in Super Definition |
GasGiant-PIA09117.jpgA "young" Gas-Giant63 visiteCaption NASA:"This is an artist's concept of a hypothetical 10-million-year-old star system. The bright blur at the center is a star much like our Sun. The other orb in the image is a gas-giant planet like Jupiter. Wisps of white throughout the image represent traces of gas.
Astronomers using NASA's Spitzer Space Telescope have found evidence showing that gas-giant planets either form within the first 10 million years of a Sun-like star's life, or not at all. The lifespan for sun-like stars is about 10 billion years.
The scientists came to this conclusion after searching for traces of gas around 15 different Sun-like stars, most with ages ranging from 3 to 30 million years. With the help of Spitzer's Infrared Spectrometer Instrument, they were able to search for relatively warm gas in the inner regions of these star systems, an area comparable to the zone between Earth and Jupiter in our own solar system. They also used ground-based radio telescopes to search for cooler gas in the outer regions of these systems, an area comparable to the zone around Saturn and beyond".MareKromium
(7 voti)
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NGC-2535-PIA09106.jpgNGC 2535 and NGC 2536 (alias Arp 82)53 visiteA pair of interacting galaxies might be experiencing the galactic equivalent of a mid-life crisis. For some reason, the pair, called Arp 82, didn't make their stars early on as is typical of most galaxies. Instead, they got a second wind later in life -- about 2 billion years ago -- and started pumping out waves of new stars as if they were young again.
Arp 82 is an interacting pair of galaxies with a strong bridge and a long tail. NGC 2535 is the big galaxy and NGC 2536 is its smaller companion. The disk of the main galaxy looks like an eye, with a bright "pupil" in the center and oval-shaped "eyelids." Dramatic "beads on a string" features are visible as chains of evenly spaced star-formation complexes along the eyelids. These are presumably the result of large-scale gaseous shocks from a grazing encounter. The colors of this galaxy indicate that the observed stars are young to intermediate in age, around 2 million to 2 billion years old, much less than the age of the universe (13.7 billion years).
The puzzle is: why didn't Arp 82 form many stars earlier, like most galaxies of that mass range? Scientifically, it is an oddball and provides a relatively nearby lab for studying the age of intermediate-mass galaxies.
This picture is a composite captured by Spitzer's infrared array camera with light at wavelength 8 microns shown in red, NASA's Galaxy Evolution Explorer combined 1530 and 2310 Angstroms shown in blue, and the Southeastern Association for Research in Astronomy Observatory light at 6940 Angstroms shown in green.
(7 voti)
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Upsilon Andromedae-PIA01937.jpgUpsilon Andromedae54 visiteThe top graph consists of infrared data from NASA's Spitzer Space Telescope. It tells astronomers that a distant planet, called Upsilon Andromedae b, always has a giant hot spot on the side that faces the star, while the other side is cold and dark. The artist's concepts above the graph illustrate how the planet might look throughout its orbit if viewed up close with infrared eyes.
Spitzer was able to determine the difference in temperature between the two sides of this planet by measuring the planet's infrared light, or heat, at five points during its 4.6-day-long trip around its star. The temperature rose and fell depending on which face, the sunlit or dark, was pointed toward Spitzer's cameras. Those temperature oscillations are traced by the wavy orange curve. They indicate that Upsilon Andromedae b has an extreme range of temperatures across its surface, about 1,400 degrees Celsius (2,550 degrees Fahrenheit). This means that hot gas moving across the bright side of the planet cools off by the time it reaches the dark side.
The bottom graph and artist's concepts represent what astronomers might have seen if the planet had bands of different temperatures girdling it, like Jupiter. Some astronomers had speculated that "hot-Jupiter" planets like Upsilon Andromedae b, which circle very closely around their stars, might resemble Jupiter in this way. If Upsilon Andromedae b had been like this, there would have been no difference between the average temperatures of the sunlit and dark sides to detect, and Spitzer's data would have appeared as a flat line.
(7 voti)
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M 74-PIA08533.jpgM 74 - Spiral Galaxy53 visite
(7 voti)
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M 74-PIA08533_fig1.jpgM 74 and Supernova SN2003gd53 visiteThis image is the galaxy M 74, as seen by SST's infrared array camera. The white box to the left of the Galaxy's center identifies the location of the Supernova Remnant. In all the images, the blue dots represent hot gas and stars. The galaxy's cool dust is shown in red.
Astronomers using NASA's SST have spotted a "dust factory" 30 MLY away in the spiral galaxy M 74. The factory is located at the scene of a massive star's explosive death, or supernova.
While astronomers have suspected for years that supernovae could be producers of cosmic dust particles, the technology to confirm this suspicion has only recently become available.
(7 voti)
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Kepler_10b-PIA13776.jpgExo-Planet "Kepler 10b"153 visiteCaption NASA:"Artist's concept of the first rocky world discovered by NASA's Kepler Mission. The Planet, called Kepler 10-b, is shown in front of its Host (Parent) Star".MareKromium
(6 voti)
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Galactic_Center-PIA12074.jpgNewborn Stars found near the Galactic Centre54 visiteThis InfraRed image from NASA's Spitzer Space Telescope shows 3 "baby stars" in the bustling center of our Milky Way galaxy.
The three stars are the first to be discovered in the region — previous attempts to find them were unsuccessful because there is so much dust standing between us and our galaxy's core.
Spitzer was able to find the newborn stars with its sharp InfraRed eyes, which can cut through dust.
The center of our galaxy is a hectic place. It's stuffed with stars, gas and dust. Astronomers have long wondered how stars can form in such chaotic circumstances. While they have known that stars are born there, they weren't able to see the stars forming until now. Astronomers plan to search for more newborn stars in the region, and ultimately learn more about stellar births at the center of the Milky Way.MareKromium
(6 voti)
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M-033-a.jpgM 33 - The "Triangulum" Spiral Galaxy (a.k.a. NGC 598)54 visiteNASA's Galaxy Evolution Explorer Mission celebrates its sixth anniversary studying galaxies beyond our Milky Way through its sensitive UltraViolet telescope, the only such far-UltraViolet detector in space.
The mission studies the shape, brightness, size and distance of distant galaxies across 10 BY of cosmic history, giving scientists a wealth of data to help us better understand the origins of the universe. One such object is pictured here, the galaxy NGC 598, more commonly known as M 33.
The image shows a map of the recent star formation history of M 33. The bright blue and white areas are where star formation has been extremely active over the past few million years. The patches of yellow and gold are regions where star formation was more active 100 MY ago.
In addition, the UltraViolet image shows the most massive young stars in M 33. These stars burn their large supply of Hydrogen fuel quickly, burning hot and bright while emitting most of their energy at UV wavelengths. Compared with low-mass stars like our Sun, which live for billions of years, these massive stars never reach old age, having a lifespan as short as a few million years.
The California Institute of Technology, in Pasadena, Calif., leads the Galaxy Evolution Explorer Mission and is responsible for science operations and data analysis. NASA's Jet Propulsion Laboratory, also in Pasadena, manages the mission and built the science instrument. The mission was developed under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. South Korea and France are the mission's international partners.MareKromium
(6 voti)
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NGC-6240-PIA11828.jpgNGC 6240 - Colliding Galaxies54 visiteThis image of a pair of colliding galaxies called NGC 6240 shows them in a rare, short-lived phase of their evolution just before they merge into a single, larger galaxy. The prolonged, violent collision has drastically altered the appearance of both galaxies and created huge amounts of heat turning NGC 6240 into an "InfraRed Luminous" Active Galaxy.
A rich variety of active galaxies, with different shapes, luminosities and radiation profiles exist. These galaxies may be related astronomers have suspected that they may represent an evolutionary sequence. By catching different galaxies in different stages of merging, a story emerges as one type of active galaxy changes into another. NGC 6240 provides an important "missing link" in this process.
This image was created from combined data from the infrared array camera of NASA's Spitzer Space Telescope at 3.6 and 8.0 microns (red) and Visible Light from NASA's Hubble Space Telescope (green and blue).MareKromium
(6 voti)
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Cassiopeia_A-PIA11748.jpgSNR Cassiopeia "A"54 visiteFor the first time, a multiwavelength three-dimensional reconstruction of a SuperNova Remnant has been created. This stunning visualization of Cassiopeia A, or Cas A, the result of an explosion approximately 330 years ago, uses data from several telescopes: X-ray data from NASA's Chandra X-ray Observatory, InfraRed data from NASA's Spitzer Space Telescope and optical data from the National Optical Astronomy Observatory 4-meter telescope at Kitt Peak, Ariz., and the Michigan-Dartmouth-MIT 2.4-meter telescope, also at Kitt Peak. In this visualization, the green region is mostly Iron observed in X-rays. The yellow region is a combination of Argon and Silicon seen in X-rays, optical, and infrared — including jets of Silicon — plus outer debris seen in the optical. The red region is cold debris seen in the infrared. Finally, the blue reveals the outer blast wave, most prominently detected in X-rays.
Most of the material shown in this visualization is debris from the explosion that has been heated by a shock moving inwards. The red material interior to the yellow/orange ring has not yet encountered the inward moving shock and so has not yet been heated. These unshocked debris were known to exist because they absorb background radio light, but they were only recently discovered in infrared emission with Spitzer. The blue region is composed of gas surrounding the explosion that was heated when it was struck by the outgoing blast wave, as clearly seen in Chandra images.
To create this visualization, scientists took advantage of both a previously known phenomenon — the Doppler effect — and a new technology that bridges astronomy and medicine. When elements created inside a supernova, such as Iron, Silicon and Argon, are heated they emit light at certain wavelengths. Material moving towards the observer will have shorter wavelengths and material moving away will have longer wavelengths. Since the amount of the wavelength shift is related to the speed of motion, one can determine how fast the debris are moving in either direction.
Because Cas A is the result of an explosion, the stellar debris is expanding radially outwards from the explosion center. Using simple geometry, the scientists were able to construct a 3-D model using all of this information. A program called 3-D Slicer — modified for astronomical use by the Astronomical Medicine Project at Harvard University in Cambridge, Mass. — was used to display and manipulate the 3-D model. Commercial software was then used to create the 3-D fly-through.
The blue filaments defining the blast wave were not mapped using the Doppler Effect because they emit a different kind of light —synchrotron radiation — that does not emit light at discrete wavelengths, but rather in a broad continuum. The blue filaments are only a representation of the actual filaments observed at the blast wave.
This visualization shows that there are two main components to this supernova remnant: a spherical component in the outer parts of the remnant and a flattened (disk-like) component in the inner region. The spherical component consists of the outer layer of the star that exploded, probably made of helium and carbon. These layers drove a spherical blast wave into the diffuse gas surrounding the star.
The flattened component — that astronomers were unable to map into 3-D prior to these Spitzer observations — consists of the inner layers of the star. It is made from various heavier elements, not all shown in the visualization, such as Oxygen, Neon, Silicon, Sulphur, Argon and Iron.
High-velocity plumes, or jets, of this material are shooting out from the explosion in the plane of the disk-like component mentioned above. Plumes of Silicon appear in the North/East and South/West, while those of Iron are seen in the South/East and North. These jets were already known and Doppler velocity measurements have been made for these structures, but their orientation and position with respect to the rest of the debris field had never been mapped before now.
This new insight into the structure of Cas A gained from this 3-D visualization is important for astronomers who build models of supernova explosions. Now, they must consider that the outer layers of the star come off spherically, but the inner layers come out more disk-like with high-velocity jets in multiple directions.MareKromium
(6 voti)
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Epsilon_Eridani-PIA11376.JPGSolar Systems54 visiteThis artist's diagram compares the Epsilon Eridani System to our own Solar System. The two systems are structured similarly, and both host asteroids (brown), comets (blue) and planets (white dots).
Epsilon Eridani is our closest known planetary system, located about 10 LY away in the constellation Eridanus. Its central star is a younger, fainter version of our Sun, and is about 800 million years old — about the same age of our Solar System when life first took root on Earth.
Observations from NASA's Spitzer Space Telescope show that the System hosts two Asteroid Belts, in addition to previously identified candidate planets and an Outer Comet Ring.
Epsilon Eridani's inner Asteroid Belt is located at about the same position as ours, approximately 3 AU from its star (aone AU is the distance between Earth and Sun). The system's second, denser Belt lies at about the same place where Uranus orbits in our Solar System, or 20 AU from the star.
In the same way that Jupiter lies just outside our Asteroid Belt, shepherding its rocky debris into a ring, Epsilon Eridani is thought to have planets orbiting near the rims of its two Belts. The first of these planets was identified in 2000 via the Radial Velocity Technique.
Called "Epsilon Eridani b", it orbits at an average distance of 3,4 AU — placing it just outside the System's inner Asteroid Belt.
The second planet orbiting near the rim of the outer Asteroid Belt at 20 AU was inferred when Spitzer discovered the belt.
A third planet might orbit in Epsilon Eridani at the inner edge of its outermost Comet Ring, which lies between 35 and 90 AU. This planet was first hinted at in 1998 due to observed lumpiness in the Comet Ring.
The outer Comet Ring around Epsilon Eridani is denser than our Comet Ring, called Kuiper Belt, because the system is younger.
Over time, Epsilon Eridani's ring will become wispier like the Kuiper Belt. Its comets will collide with each other and break up, or get pushed out of the ring by the gravitational influences of the planets. MareKromium
(6 voti)
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Galaxies-HST.jpgGalaxies!54 visiteThese images taken with NASA's Hubble Space Telescope are close-up views of four galaxies from a large survey of nearby galaxies.
The galaxies have very different masses and sizes and showcase the diversity of galaxies found in the ANGST study. Although the galaxies are separated by many light-years, they are presented as if they are all at the same distance to show their relative sizes.
The images, taken with Hubble's Advanced Camera for Surveys, reveal rich detail in the stellar populations and in the interstellar dust scattered between the stars. Hubble's sharp views reveal the colors and brightnesses of individual stars, which astronomers used to derive the history of star formation in each galaxy.
In the composite image at the top, NGC 253 is ablaze with the light from thousands of young, blue stars. The spiral galaxy is undergoing intense star formation. The image demonstrates the sharp "eye" of the Advanced Camera, which resolved individual stars. The dark filaments are clouds of dust and gas. NGC 253 is the dominant galaxy in the Sculptor Group of galaxies and it resides about 13 million light-years from Earth.
In the view of the spiral galaxy NGC 300, second from top, young, blue stars are concentrated in spiral arms that sweep diagonally through the image. The yellow blobs are glowing hot gas that has been heated by radiation from the nearest young, blue stars. NGC 300 is a member of the Sculptor Group of galaxies and it is located 7 million light-years away.
The dark clumps of material scattered around the bright nucleus of NGC 3077, the small, dense galaxy at bottom, left, are pieces of wreckage from the galaxy's interactions with its larger neighbors. NGC 3077 is a member of the M81 group of galaxies and it resides 12.5 million light-years from Earth.
The image at bottom, right, shows a swarm of young, blue stars in the diffuse dwarf irregular galaxy NGC 4163. NGC 4163 is a member of a group of dwarf galaxies near our Milky Way and is located roughly 10 million light-years away.
These galaxies are part of a detailed survey called the ACS Nearby Galaxy Survey Treasury program (ANGST). In the census, Hubble observed roughly 14 million stars in 69 galaxies. The survey explored a region called the "Local Volume," and the galaxy distances ranged from 6.5 million light-years to 13 million light-years from Earth. The Local Volume resides beyond the Local Group of galaxies, an even nearer collection of a few dozen galaxies within about 3 million light-years of our Milky Way Galaxy.
The natural-color images were constructed using observations taken in infrared, visible, and blue light. The observations of NGC 253 and NGC 300 were taken in September 2006; of NGC 3077 in November 2006; and of NGC 4163 in December 2006.
Object Names: NGC 253, NGC 300, NGC 3077, NGC 4163
MareKromium
(6 voti)
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