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| Piú votate - The Universe in Super Definition |
PIA13120.jpgWISE Eyes...61 visiteThis frame shows the progress of the WISE All-Sky Survey at the present time. WISE, or NASA's Wide-field InfraRed Survey Explorer, is perched up in the sky like a wise, old owl, scanning the whole sky one-and-a-half times in IR Light. On July 17, 2010, it will have completed its first scan of the entire sky, delivering more than one million image frames so far.
This map is filled in to show the sky areas that WISE scanned over time. Red indicates regions with the greatest coverage, and blue the least. The Poles received the most coverage because WISE orbits Earth around the Poles, scanning out strips of sky as Earth moves around the Sun. The red lines between the Poles show areas that received extra coverage because of the mission's strategy to avoid the Moon.
When the moon is in WISE's field of view, about twice every month, the space telescope captures the region it blocks, by first moving ahead of the moon and then behind it. This results in overlapped coverage for certain slices of sky. During this first all-sky scan, every point was covered by at least eight image frames.
The Infrared Astronomical Satellite was a joint project of the United States, United Kingdom and the Netherlands.
The Two-Micron All-Sky Survey was a project of NASA; the National Science Foundation; the University of Massachusetts, Amherst, and the California Institute of Technology, Pasadena, California.MareKromium
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30-Doradus.jpg30 Doradus and R-13655 visiteThe massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way. Many of the stars are among the most massive known. Several of them are over 100 times more massive than our Sun. These hefty stars are destined to become supernovae in a few million years.
The image, taken by Hubble's Wide Field Camera 3, spans about 100 light-years. The nebula is close enough to Earth that Hubble can resolve individual stars, giving astronomers important information about the stars' birth and evolution.
The brilliant stars are carving deep cavities in the surrounding material by unleashing a torrent of ultraviolet light, and hurricane-force stellar winds (streams of charged particles), which are etching away the enveloping hydrogen gas cloud in which the stars were born. The image reveals a fantasy landscape of pillars, ridges, and valleys, as well as a dark region in the center that roughly looks like the outline of a holiday tree. Besides sculpting the gaseous terrain, the brilliant stars can also help create a successive generation of offspring. When the winds hit dense walls of gas, they create shocks, which may be generating a new wave of star birth.
The movement of the LMC around the Milky Way may have triggered the massive cluster's formation in several ways. The gravitational tug of the Milky Way and the companion Small Magellanic Cloud may have compressed gas in the LMC. Also, the pressure resulting from the LMC plowing through the Milky Way's halo may have compressed gas in the satellite. The cluster is a rare, nearby example of the many super star clusters that formed in the distant, early universe, when star birth and galaxy interactions were more frequent. Previous Hubble observations have shown astronomers that super star clusters in faraway galaxies are ubiquitous. The LMC is located 170,000 light-years away and is a member of the Local Group of Galaxies, which also includes the Milky Way.
The Hubble image was taken at infrared wavelengths (1.1 microns and 1.6 microns). Hubble sees through the dusty nebula, revealing many stars that cannot be seen in visible light. The large bright star just above the center of the image is in the 30 Doradus nebula. The Hubble observations of 30 Doradus were made October 20-27, 2009.MareKromium
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M-083-a.jpgHubble Wide Field Camera 3 - Image Details Star Birth in Galaxy M-8354 visiteThe spectacular new camera installed on NASA's Hubble Space Telescope during Servicing Mission 4 in May has delivered the most detailed view of star birth in the graceful, curving arms of the nearby spiral galaxy M83.
Nicknamed the Southern Pinwheel, M83 is undergoing more rapid star formation than our own Milky Way galaxy, especially in its nucleus. The sharp "eye" of the Wide Field Camera 3 (WFC3) has captured hundreds of young star clusters, ancient swarms of globular star clusters, and hundreds of thousands of individual stars, mostly blue supergiants and red supergiants.
The image, taken in August 2009, provides a close-up view of the myriad stars near the galaxy's core, the bright whitish region at far right.
WFC3's broad wavelength range, from ultraviolet to near-infrared, reveals stars at different stages of evolution, allowing astronomers to dissect the galaxy's star-formation history.
The image reveals in unprecedented detail the current rapid rate of star birth in this famous "grand design" spiral galaxy. The newest generations of stars are forming largely in clusters on the edges of the dark dust lanes, the backbone of the spiral arms. These fledgling stars, only a few million years old, are bursting out of their dusty cocoons and producing bubbles of reddish glowing hydrogen gas.
The excavated regions give a colorful "Swiss cheese" appearance to the spiral arm. Gradually, the young stars' fierce winds (streams of charged particles) blow away the gas, revealing bright blue star clusters. These stars are about 1 million to 10 million years old. The older populations of stars are not as blue.
A bar of stars, gas, and dust slicing across the core of the galaxy may be instigating most of the star birth in the galaxy's core. The bar funnels material to the galaxy's center, where the most active star formation is taking place. The brightest star clusters reside along an arc near the core.
The remains of about 60 supernova blasts, the deaths of massive stars, can be seen in the image, five times more than known previously in this region. WFC3 identified the remnants of exploded stars. By studying these remnants, astronomers can better understand the nature of the progenitor stars, which are responsible for the creation and dispersal of most of the galaxy's heavy elements.
M83, located in the Southern Hemisphere, is often compared to M51, dubbed the Whirlpool galaxy, in the Northern Hemisphere. Located 15 million light-years away in the constellation Hydra, M83 is two times closer to Earth than M51.
MareKromium
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IC-348-PIA12210.jpgCreation...104 visiteThis artist's conception shows a lump of material in a swirling, planet- forming disk. Astronomers using NASA's Spitzer Space Telescope found evidence that a companion to a star -- either another star or a planet -- could be pushing planetary material together, as illustrated here.
Planets are born out of spinning disks of gas and dust. They can carve out lanes or gaps in the disks as they grow bigger and bigger. Scientists used Spitzer's infrared vision to study the disk around a star called LRLL 31, located about 1000 LY away in the IC 348 Region of the constellation Perseus. Spitzer's new infrared observations reveal that the disk has both an inner and outer gap.
What's more, the data show that infrared light from the disk is changing over as little time as one week -- a very unusual occurrence. In particular, light of different wavelengths seesawed back and forth, with short-wavelength light going up when long-wavelength light went down, and vice versa.
According to astronomers, this change could be caused by a companion to the star (illustrated as a planet in this picture). As the companion spins around, its gravity would cause the wall of the inner disk to squeeze into a lump. This lump would also spin around the star, shadowing part of the outer disk. When the bright side of the lump is on the far side of the star, and facing Earth, more infrared light at shorter wavelengths should be observed (hotter material closer to the star emits shorter wavelengths of infrared light). In addition, the shadow of the lump should cause longer-wavelength infrared light from the outer disk to decrease. The opposite would be true when the lump is in front of the star and its bright side is hidden (shorter-wavelength light would go down, and longer- wavelength light up). This is precisely what Spitzer observed.
The size of the lump and the planet have been exaggerated to better illustrate the dynamics of the system.MareKromium
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VB10-b-PIA12014.jpgThe VB10 Star System and the Solar System55 visiteThis artist's diagram compares our Solar System (below) to the VB 10 Star System. Astronomers successfully used the astrometry planet-hunting method for the first time to discover a gas planet, called VB 10b, around a very tiny star, VB 10. All of the bodies in this diagram are shown in circular insets at the same relative scales.
The VB 10 star is one of the smallest known — and holds the record for the smallest known to host a planet. It's a dim, red M-dwarf with only one-tenth the size, and one-twelfth the mass, of our sun. Its planet, on the other hand, is quite hefty, with six times the mass of Jupiter. Though the planet is less massive than the star, the two orbs would be about the same size.
The VB 10 Star System is essentially a shrunken version of our Solar System. Even though its planet is at a similar distance from its star as Mercury is from our Sun, it wouldn't receive as much heat and would be classified as a "cold Jupiter" similar to our own. If any rocky planets do orbit in the VB 10 System, they would be located even closer in than VB 10b, and could lie within the star's "Habitable Zone" — a region where temperatures are right for water to be liquid.
Astrometry involves measuring the wobble of a star on the sky, caused by an unseen planet yanking it back and forth. Because the VB 10b Planet is so big relative to its star, it really tugs the star around. The red circle seen at the center of the VB 10 system shows just how big this wobble is. Because our sun is more massive than VB 10, its planets do not cause it to wobble nearly as much.MareKromium
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NGC-2841-PIA12001.jpgNGC 2841 - Spiral Galaxy55 visiteThis image from NASA's Spitzer Space Telescope shows the Spiral Galaxy NGC 2841, located about 46 MLY from Earth in the constellation Ursa Major. The galaxy is helping astronomers solve one of the oldest puzzles in astronomy: Why do galaxies look so smooth, with stars sprinkled evenly throughout?
An international team of astronomers has discovered that rivers of young stars flow from their hot, dense stellar nurseries, dispersing out to form large, smooth distributions.
This image is a composite of three different wavelengths from Spitzer's InfraRed Array Camera. The shortest wavelengths are displayed in blue, and mostly show the older stars in NGC 2841, as well as foreground stars in our own Milky Way galaxy. The cooler areas are highlighted in red, and show the dusty, gaseous regions of the galaxy.
Blue shows InfraRed Light of 3,6 microns, green represents 4,5-micron light and red, 8,0-micron light. The contribution from starlight measured at 3,6 microns has been subtracted from the 8,0-micron data to enhance the visibility of the dust features. The shortest wavelengths are displayed in blue, and mostly show the older stars in NGC 2841, as well as foreground stars in our own Milky Way Galaxy.MareKromium
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K4-55-HST.jpgK4-55 Planetary Nebula54 visiteThe Hubble Community bids farewell to the soon-to-be decommissioned Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope.
In tribute to Hubble's longest-running optical camera, Planetary Nebula K 4-55 has been imaged as WFPC2's final "pretty picture".MareKromium
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Sharpless308-Goldman.jpgSharpless 30854 visiteCaption NASA:"Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 308 it lies some 5200 LY away in the constellation Canis Major and covers over 2/3° on the sky (compared with 0,5° for the Full Moon). That corresponds to a diameter of 60 LY at its estimated distance. The massive star itself, a Wolf-Rayet Star, is the bright blue one near the center of the Nebula.
Wolf-Rayet Stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet Star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution.
The windblown nebula has an age of about 70.000 years. Relatively faint emission captured in the expansive image is dominated by the glow of Ionized Oxygen atoms mapped to bluish hues".MareKromium
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NGC-3242-PIA11968.jpgThe Extended Region around the Planetary Nebula NGC 324254 visiteThe unfortunate name of Planetary Nebula for this class of Celestial Objects is a historical legacy credited to William Herschel during the 18th Century — a time when telescopes where small and objects like these, at least the central region, looked very similar to gas-giant planets such as Saturn and Jupiter. In fact, NGC 3242 has no relation to Jupiter or any other planet.
Telescopes and their detectors have dramatically improved over the past few centuries. Our understanding of what Planetary Nebulae truly are has improved accordingly.
When stars with a mass similar to our Sun approach the end of their lives by exhausting supplies of Hydrogen and Helium fuel in their cores, they swell up into cool red-giant stars. In a last gasp before death, they expel the layers of gas in their Outer Atmosphere. This exposes the core of the dying star, a dense hot ball of Carbon and Oxygen called a "White Dwarf".
The White Dwarf is so hot that it shines very brightly in the UltraViolet Spectrum. The UltraViolet Light from the White Dwarf, in turn, ionizes the gaseous material expelled by the star causing it to glow. A Planetary Nebula is really the death of a low-mass star.
Although low-mass stars like our Sun live for billions of years, Planetary Nebulae only last for about ten thousand years. As the central white dwarf quickly cools and the UltraViolet Light dwindles, the surrounding gas also cools and fades.
In this image of NGC 3242 from the Galaxy Evolution Explorer, the Extended Region around the Planetary Nebula is shown in dramatic detail. The small circular white and blue area at the center of the image is the well-known portion of the famous Planetary Nebula. The precise origin and composition of the extended wispy white features is not known for certain. It is most likely material ejected during the star's red-giant phase before the White Dwarf was exposed.
However, it may be possible that the extended material is simply interstellar gas that, by coincidence, is located close enough to the White Dwarf to be energized by it, and induced to glow with UltraViolet Light.
NGC 3242 is located 1400 to 2500 Light-Years away in the constellation of Hydra. It was discovered by William Herschel in 1785.MareKromium
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HD-80606b.jpgA Dangerous Summer on HD 80606b54 visiteOn the distant planet HD 80606b, Summers might be dangerous.
Hypothetic life forms floating in HD 080606b's Atmosphere or lurking on one of its (presently hypothetical) moons might fear the 1500 Kelvin Summer heat, which is hot enough not only to melt Lead but also Nickel. Although Summers are defined for Earth by the daily amount of Sunlight, Summers on HD 80606b are more greatly influenced by how close the Planet gets to its Parent Star.
HD 80606b, about 200 LY distant, has the most elliptical orbit of any planet yet discovered. In comparison to the Solar System, the distance to its Parent Star would range from outside the orbit of Venus to well inside the orbit of Mercury.
In this sequence, the night side of HD 80606b is computer simulated as it might glow in infrared light in nearly daily intervals as it passed the closest point in its 111-day orbit around its Parent Star.
The simulation is based on infrared data taken in late 2007 by the Spitzer Space Telescope.
Nota Lunexit (a chi interessa): la Formula di Conversione per le Temperature espresse in Kelvin in Temperature espresse in Celsius è la seguente: T° Celsius = T Kelvin - 273,15
Nel nostro caso di specie, quindi, la temperatura diurna media Estiva di HD 80606b dovrebbe essere pari a circa 1227° C.
Un bel "tepore", davvero...MareKromium
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SNR-Tycho-SR-PIA11435.jpgTycho: the most colourful Supernova Remnant55 visiteThis composite image of the Tycho Supernova Remnant combines InfraRed and X-Ray observations obtained with NASA's Spitzer and Chandra space observatories, respectively, and the Calar Alto observatory, Spain.
It shows the scene more than four centuries after the brilliant star explosion witnessed by Tycho Brahe and other astronomers of that era.
The explosion has left a blazing hot cloud of expanding debris (green and yellow). The location of the blast's outer shock wave can be seen as a blue sphere of ultra-energetic electrons. Newly synthesized dust in the ejected material and heated pre-existing dust from the area around the supernova radiate at infrared wavelengths of 24 microns (red).
Foreground and background stars in the image are white.MareKromium
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SN-1006-PIA10926.jpgStars and a Stripe in Celestial Fireworks56 visiteA delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago.
On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away.
It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred.
In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas.
The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed "snapshot" of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight.
Today we know that SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image as displayed, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left.
SN 1006 resides within our Milky Way Galaxy. Located more than 14 degrees off the plane of the galaxy's disk, there is relatively little confusion with other foreground and background objects in the field when trying to study this object. In the Hubble image, many background galaxies (orange extended objects) far off in the distant universe can be seen dotting the image. Most of the white dots are foreground or background stars in our Milky Way galaxy.
This image is a composite of hydrogen-light observations taken with Hubble's Advanced Camera for Surveys in February 2006 and Wide Field Planetary Camera 2 observations in blue, yellow-green, and near-infrared light taken in April 2008. The supernova remnant, visible only in the hydrogen-light filter was assigned a red hue in the Heritage color image.
For images and more information about SN 1006, visit:
http://hubblesite.org/news/2008/22
http://heritage.stsci.edu/2008/22
For additional information, contact:
Ray Villard Space Telescope Science Institute, Baltimore, Md. 410-338-4514 villard@stsci.edu
William Blair Johns Hopkins University, Baltimore, Md. 410-516-8447 wpb@pha.jhu.edu
MareKromium
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