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| Piú viste - The Universe in Super Definition |
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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COROT7b-ESO.jpgExo-Planet CoRoT-7b55 visiteHow similar is exoplanet CoRoT-7b to Earth?
The newly discovered Extra-Solar Planet is the closest physical match yet, with a mass about five Earths and a radius of about 1,7 Earths. Also, the home star to CoRoT-7b, although 500 LY distant, is very similar to our Sun.
Unfortunately, the similarities likely end there, as CoRoT-7b orbits its home star well inside the orbit of Mercury, making its year last only 20 hours, and making its peak temperature much hotter than humans might find comfortable. CoRoT-7b was discovered in February by noting a predictable slight decrease in the brightness of its parent star.
Pictured above, an artist's depiction shows how CoRoT-7b might appear in front of its Parent Star. The composition of CoRoT-7b remains unknown, but given its size and mass, it cannot be a gas giant like Jupiter, and is very likely composed predominantly of rock. Future observations will likely narrow the composition of one of the first known rocky planets discovered outside of our Solar System.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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NGC-2207-PIA08097.jpgNGC 2207 and IC 2163: Colliding Galaxies54 visiteThese shape-shifting galaxies have taken on the form of a giant mask. The icy blue eyes are actually the cores of two merging galaxies, called NGC 2207 and IC 2163, and the mask is their spiral arms. The false-colored image consists of infrared data from NASA's Spitzer Space Telescope (red) and visible data from NASA's Hubble Space Telescope (blue/green).
NGC 2207 and IC 2163 met and began a sort of gravitational tango about 40 million years ago. The two galaxies are tugging at each other, stimulating new stars to form. Eventually, this cosmic ball will come to an end, when the galaxies meld into one. The dancing duo is located 140 million light-years away in the Canis Major constellation.
The infrared data from Spitzer highlight the galaxies' dusty regions, while the visible data from Hubble indicates starlight. In the Hubble-only image (not pictured here), the dusty regions appear as dark lanes.
The Hubble data correspond to light with wavelengths of .44 and .55 microns (blue and green, respectively). The Spitzer data represent light of 8 microns.
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Life-PIA03538.jpgLife!54 visiteThis artist's conception symbolically represents complex organic molecules, known as polycyclic aromatic hydrocarbons, seen in the early universe. These large molecules, comprised of carbon and hydrogen, are considered among the building blocks of life.
NASA's Spitzer Space Telescope is the first telescope to see polycyclic aromatic hydrocarbons so early -- 10 billion years further back in time than seen previously. Spitzer detected these molecules in galaxies when our universe was one-fourth of its current age of about 14 billion years.
These complex molecules are very common on Earth. They form any time carbon-based materials are not burned completely. They can be found in sooty exhaust from cars and airplanes, and in charcoal broiled hamburgers and burnt toast.
Polycyclic aromatic hydrocarbons are pervasive in galaxies like our own Milky Way, and play a significant role in star and planet formation.
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N76-PIA08516-2.jpgThe "N 76 Nebula"54 visiteThe supernova remnant1E0102.2-7219 sits next to the Nebula N76 in a bright, Star-Forming Region of the Small Magellanic Cloud, a satellite galaxy to our Milky Way galaxy located about 200.000 LY from Earth. A Supernova Remnant is made up of the messy bits and pieces of a massive star that exploded, or went Supernova. This image shows glowing dust grains in three wavelengths of infrared radiation: 24 microns (red) measured by the Multiband Imaging Photometer aboard NASA's Spitzer Space Telescope; and 8.0 microns (green) and 3.6 microns (blue) measured by Spitzer's infrared array camera. The red bubble is a dust envelope around the supernova remnant E0102, which is being heated by the shock wave created in the explosion of the remnant's massive progenitor star some 1,000 years ago. Most of the blue stars are in the Small Magellanic Cloud, though some are in our own galaxy.
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Black Hole-PIA08696.jpgBlack Hole54 visiteThis artist's concept depicts a supermassive black hole at the center of a galaxy. NASA's Galaxy Evolution Explorer found evidence that black holes -- once they grow to a critical size -- stifle the formation of new stars in elliptical galaxies. Black holes are thought to do this by heating up and blasting away the gas that fuels star formation.
The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Beyond the torus, only the old red-colored stars that make up the galaxy can be seen. There are no new stars in the galaxy.
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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.
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NGC-1313.jpgNCG 1313 - Barred Spiral54 visite"...You have no idea how much nastier would be if I was not a Catholic.
Without "Supernatural Aid" I would hardly be a human being..."
Evelyn Waugh (1903 - 1966) - replying to Nancy Mitford who rebuked her for cruelty
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Spectrum-PIA09197.jpgSpectrum of an Alien World54 visiteThis infrared data from NASA's Spitzer Space Telescope - called a spectrum - tells astronomers that a distant gas planet, a so-called "hot Jupiter" called HD 209458b, might be smothered with high clouds. It is one of the first spectra of an alien world.
A spectrum is created when an instrument called a spectrograph cracks light from an object open into a rainbow of different wavelengths. Patterns or ripples within the spectrum indicate the presence, or absence, of molecules making up the object.
Astronomers using Spitzer's spectrograph were able to obtain infrared spectra for two so-called "transiting" hot-Jupiter planets using the "secondary eclipse" technique. In this method, the spectrograph first collects the combined infrared light from the planet plus its star, then, as the planet is eclipsed by the star, the infrared light of just the star. Subtracting the latter from the former reveals the planet's own rainbow of infrared colors.
When astronomers first saw the infrared spectrum above, they were shocked. It doesn't look anything like what theorists had predicted. For example, theorists thought there'd be signatures of water in the wavelength ranges of 8 to 9 microns. The fact that water is not detected might indicate that it is hidden under a thick blanket of high, dry clouds.
In addition, the spectrum shows signs of silicate dust -- tiny grains of sand -- in the wavelength range of 9 to 10 microns. This suggests that the planet's skies could be filled with high clouds of dust unlike anything seen in our own solar system.
There is also an unidentified molecular signature at 7.78 microns. Future observations using Spitzer's spectrograph should be able to determine the nature of the mysterious feature.
This spectrum was produced by Dr. Jeremy Richardson of NASA's Goddard Space Flight Center, Greenbelt, Md. and his colleagues. The data were taken by Spitzer's infrared spectrograph on July 6 and 13, 2005.
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SN-1987A.jpgSupernova 1987A54 visiteTwenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.
Observations of SN 1987A, made over the past 20 years by NASA's Hubble Space Telescope and many other major ground- and space-based telescopes, have significantly changed astronomers' views of how massive stars end their lives. Astronomers credit Hubble's sharp vision with yielding important clues about the massive star's demise.
"The sharp pictures from the Hubble telescope help us ask and answer new questions about Supernova 1987A," said Robert Kirshner, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "In fact, without Hubble we wouldn't even know what to ask."
Kirshner is the lead investigator of an international collaboration to study the doomed star. Studying supernovae like SN 1987A is important because the exploding stars create elements, such as carbon and iron, that make up new stars, galaxies, and even humans. The iron in a person's blood, for example, was manufactured in supernova explosions. SN 1987A ejected 20,000 Earth masses of radioactive iron. The core of the shredded star is now glowing because of radioactive titanium that was cooked up in the explosion.
The star is 163,000 light-years away in the Large Magellanic Cloud. It actually blew up about 161,000 B.C., but its light arrived here in 1987.
Kirshner has used the Hubble telescope to monitor the supernova. "The Hubble observations have helped us rewrite the textbooks on exploding stars. We found that the actual world is more complicated and interesting than anyone dared to imagine. There are mysterious triple rings of glowing gas and powerful blasts sent out from the explosion that are just having an impact now, 20 years later."
Before SN 1987A, astronomers had a "simplified, idealized model of a supernova," Kirshner explained. "We thought the explosions were spherical and we didn't think much about the gas a star would exhale in the thousands of years before it exploded. The actual shreds of the star in SN 1987A are elongated — more like a jellybean than a gumball, and the fastest-moving debris is slamming into the gas that was already out there from previous millennia. Who would have guessed?"
Hubble wasn't even around when astronomers first spotted the supernova in 1987. When Hubble was launched three years later, astronomers didn't waste any time in using the telescope to study the stellar blast. Its first peek was in 1990, the year the observatory launched. Since then, the telescope has taken hundreds of pictures of the doomed star.
The Hubble studies have revealed the following details about the supernova:
*A glowing ring, about a light-year in diameter, around the supernova. The ring was there at least 20,000 years before the star exploded. X-rays from the explosion energized the gas in the ring, making it glow for two decades.
*Two outer loops of glowing gas, which had been imaged by ground-based telescopes, were seen more clearly by Hubble.
*A dumbbell-shaped central structure that has now grown to one-tenth of a light-year long. The structure consists of two blobs of debris in the center of the supernova racing away from each other at roughly 20 million miles an hour.
*The onrushing stellar shock wave from the stellar explosion is slamming into, heating up, and illuminating the inner regions of the narrow ring surrounding the doomed star.
Hubble continues to watch as the blast debris moves through the ring. The light show makes the glowing ring look like a pearl necklace. Astronomers think the whole ring will be illuminated in a few years.
The glowing ring is expected to become bright enough to illuminate the star's surroundings, which will provide astronomers with new information on how the star ejected material before the explosion.
Astronomers are analyzing images by NASA's Spitzer Space Telescope to try to understand the fate of the dust that surrounds the exploded star and in the neighborhood around the blast.
"We will learn more in the future when the shock wave moves through the inner ring and slams into the outer rings and illuminates them," Kirshner said. "It could lead to clues about the last 20,000 years of the star. But there are many things that are still a mystery. We still do not understand the evolution of the star before the explosion or how the three rings formed. We also think that the star may be part of a binary system."
Astronomers also are still looking for evidence of a black hole or a neutron star left behind by the blast. The fiery death of massive stars usually creates these energetic objects. Most astronomers think a neutron star formed 20 years ago. Kirshner said the object could be obscured by dust or it could have become a black hole.
He plans to use the infrared capabilities of the Wide Field Camera 3 — an instrument scheduled to be installed during the upcoming Hubble servicing mission — to hunt for a stellar remnant. Scientists will use another instrument planned for installment during the mission, the Cosmic Origins Spectrograph, to analyze the supernova's chemical composition and velocities.
The James Webb Space Telescope, scheduled for launch in 2013, will be able to see infrared light from the ring that is 10 times fainter than what astronomers see today. The debris inside the ring will begin to brighten, and astronomers will get another chance to study the interior of an exploded star.
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Supernova-PIA09119.jpgBipolar Nebula54 visiteCaption NASA:"A luminous blue variable star in our galaxy, named HD168625, surrounded by a bipolar nebula that is similar to the one around SN1987A.
SN1987A was a supernova that exploded in 1987 in the Large Magellanic Cloud, and was the nearest supernova in about 400 years.
Rings near the equator are sometimes seen around stars that shed mass from their surfaces, but the larger rings above the poles are very rare. Tipped toward Earth and illuminated by the star, the rings look like ellipses in images taken with NASA's Spitzer Space Telescope.
The image was taken in 2004 by the infrared array camera on Spitzer at wavelengths between 3,6 and 8 microns. The massive star at the center, which lies within the constellation Sagittarius, is about 7.200 Light-Years from Earth". MareKromium
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