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Astronomers Map a Hypergiant
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| Title |
Astronomers Map a Hypergiant Star's Massive Outbursts |
| General Information |
What is an American Astronomical Society Meeting release? A major news announcement issued at an American Astronomical Society meeting, the premier astronomy conference. Using NASA's Hubble Space Telescope and the W.M. Keck Observatory, Kameula, Hawaii, astronomers have learned that the gaseous outflow from one of the brightest super-sized stars in the sky is more complex than originally thought. The outbursts are from VY Canis Majoris, a red supergiant star that is also classified as a hypergiant because of its very high luminosity. The eruptions have formed loops, arcs, and knots of material moving at various speeds and in many different directions. The star has had many outbursts over the past 1,000 years as it nears the end of its life. Read more: * The Full Story [ http://hubblesite.org/newscenter/archive/releases/2007/03/full/ ] |
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Eris: The Largest Known Dwar
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| Title |
Eris: The Largest Known Dwarf Planet |
| Explanation |
Is Pluto the largest dwarf planet? No! Currently, the largest known dwarf planet is (136199) Eris [ http://en.wikipedia.org/wiki/136199_Eris ], renamed last week from 2003 UB313 [ http://antwrp.gsfc.nasa.gov/apod/ap060207.html ]. Eris is just slightly larger than Pluto, but orbits as far as twice Pluto [ http://antwrp.gsfc.nasa.gov/apod/ap060903.html ]'s distance from the Sun. Eris is shown above [ http://www.keckobservatory.org/view_album.php?album_id=4 ] in an image taken by a 10-meter Keck Telescope [ http://antwrp.gsfc.nasa.gov/apod/ap971227.html ] from Hawaii [ http://antwrp.gsfc.nasa.gov/apod/ap951216.html ], USA [ https://www.cia.gov/cia/publications/factbook/geos/us.html ]. Like Pluto, Eris has a moon, which has been officially named [ http://cfa-www.harvard.edu/iau/special/08747.pdf ] by the International Astronomical Union [ http://www.iau.org/ ] as (136199) Eris I (Dysnomia). Dysnomia [ http://en.wikipedia.org/wiki/Dysnomia_%28moon%29 ] is visible above just to the right of Eris. Dwarf planets [ http://en.wikipedia.org/wiki/Dwarf_planet ] Pluto and Eris are trans-Neptunian objects [ http://www.planetary.org/explore/topics/trans_neptunian_objects/ ] that orbit in the Kuiper belt [ http://www.ifa.hawaii.edu/~jewitt/kb.html ] of objects past Neptune. Eris [ http://antwrp.gsfc.nasa.gov/apod/ap050801.html ] was discovered in 2003, and is likely composed of frozen water-ice and methane [ http://en.wikipedia.org/wiki/Methane ]. Since Pluto's recent demotion by the IAU [ http://en.wikipedia.org/wiki/International_Astronomical_Union ] from planet to dwarf planet status, Pluto [ http://voyagesolarsystem.org/gallery/gallery_10.html ] has recently also been given a new numeric designation: (134340) Pluto. Currently, the only other officially designated "dwarf planet" is (1) Ceres [ http://antwrp.gsfc.nasa.gov/apod/ap060821.html ]. |
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LkHa101: The Hole in the Dou
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| Title |
LkHa101: The Hole in the Doughnut |
| Explanation |
You'd need a really big cup of coffee with this doughnut [ http://www.physics.usyd.edu.au/~gekko/ doughnut.html ] ... because the hole in the middle is about a billion kilometers across. Centered on the Sun, a circle that size would lie between the orbits of Mars and Jupiter. In fact, this doughnut is known to surround a massive newborn star cataloged as LkHa 101 which lies in the constellation Perseus [ http://www.allthesky.com/constellations/perseus/ constell.html ]. Imaged in infrared light [ http://cfa-www.harvard.edu/newtop/whatsnew.html ], the tantalizing torus-shaped cloud of gas and dust [ http://stardust.wustl.edu/IDPIntro.html ] is slightly tilted to our view. The cloud's material may well be the ingredients for the formation of a distant solar system [ http://www.spaceart.org/lcook/extrasol.html ]. A bright source of ultraviolet light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/ multiwavelength.html ], the hot young star itself is much fainter in the infrared and so not visible in this picture. Still, the star's presence is indicated as its intense stellar wind and radiation has apparently carved out the doughnut's hole. This premier close-up of a stellar system in formation was accomplished by adapting a powerful observational technique called interferometry [ http://www.sciam.com/2001/0301issue/0301armstrong.html ] to planet Earth's largest single mirror telescope, the 10 meter Keck [ http://www2.keck.hawaii.edu:3636/ ]. |
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Land of Three Suns (Artist's
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PIA03520
Keck I Telescope
| Title |
Land of Three Suns (Artist's Concept Animation) |
| Original Caption Released with Image |
Figure 1: Sifting the Light of Three Suns This artist's animation shows the view from a hypothetical moon in orbit around the first known planet to reside in a tight-knit triple-star system. HD 188553 Ab is a gas giant planet, about 1.14 times the mass of Jupiter, with an orbital period of 3.3 days discovered using the Keck I telescope atop Mauna Kea in Hawaii, and zips around a single star that is orbited by a nearby pair of pirouetting stars. Because the stars in this triple system are bunched together, sunsets on the planet -- or on any moons that might exist around the planet -- would be spectacular. This rambunctious stellar family is called HD188753 and is located 149 light-years away in the constellation Cygnus. In this movie, sunset is seen through the tenuous atmosphere of a hot, baked hypothetical moon. As the suns dip below the horizon, the gas giant comes into view. The moon's landscape remains illuminated by sunlight reflected off the planet. Both the planet and moon would be so hot that even in shadow their surfaces would glow. The suns' colors and sizes reflect their masses, temperatures and distances to the planet. For example, the first star shown setting over the horizon is the closest, most massive and hottest of the trio, so it is depicted as large and white. The second star is farther away, less massive and cooler than the first, appearing smaller and yellow. The final star is at the same distance as the second, but it is still less massive and cooler, appearing even smaller and orange-red in color. Our Sun is a bit cooler than the hottest star of the system. The graph in figure 1 shows the "wobble" of a star being tugged on by the planet called HD 188753 Ab. The planet was discovered via the radial velocity technique, in which a planet's presence is inferred by the motion, or wobble, it causes in its parent star. Stellar motion is plotted here as changes in velocity (y-axis) versus time (x-axis). Unlike most planetary wobbles, this one comes from a star that is circled by a nearby pair of stars. In other words, the planet orbits a single star that is part of a close-knit triple-star system. Because the starlight from this cramped bunch blends together, the task of sifting through the light to find the planet's signature was more difficult. This challenge was overcome with the help of detailed models of the triple-star system's light. Data from those models resulted in precise velocity measurements of the star circled by HD 188753 Ab. Note: The size of the Full-Res TIFF for the still image is 3200 samples x 2400 lines. |
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Land of Three Suns (Artist's
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PIA03520
Keck I Telescope
| Title |
Land of Three Suns (Artist's Concept Animation) |
| Original Caption Released with Image |
Figure 1: Sifting the Light of Three Suns This artist's animation shows the view from a hypothetical moon in orbit around the first known planet to reside in a tight-knit triple-star system. HD 188553 Ab is a gas giant planet, about 1.14 times the mass of Jupiter, with an orbital period of 3.3 days discovered using the Keck I telescope atop Mauna Kea in Hawaii, and zips around a single star that is orbited by a nearby pair of pirouetting stars. Because the stars in this triple system are bunched together, sunsets on the planet -- or on any moons that might exist around the planet -- would be spectacular. This rambunctious stellar family is called HD188753 and is located 149 light-years away in the constellation Cygnus. In this movie, sunset is seen through the tenuous atmosphere of a hot, baked hypothetical moon. As the suns dip below the horizon, the gas giant comes into view. The moon's landscape remains illuminated by sunlight reflected off the planet. Both the planet and moon would be so hot that even in shadow their surfaces would glow. The suns' colors and sizes reflect their masses, temperatures and distances to the planet. For example, the first star shown setting over the horizon is the closest, most massive and hottest of the trio, so it is depicted as large and white. The second star is farther away, less massive and cooler than the first, appearing smaller and yellow. The final star is at the same distance as the second, but it is still less massive and cooler, appearing even smaller and orange-red in color. Our Sun is a bit cooler than the hottest star of the system. The graph in figure 1 shows the "wobble" of a star being tugged on by the planet called HD 188753 Ab. The planet was discovered via the radial velocity technique, in which a planet's presence is inferred by the motion, or wobble, it causes in its parent star. Stellar motion is plotted here as changes in velocity (y-axis) versus time (x-axis). Unlike most planetary wobbles, this one comes from a star that is circled by a nearby pair of stars. In other words, the planet orbits a single star that is part of a close-knit triple-star system. Because the starlight from this cramped bunch blends together, the task of sifting through the light to find the planet's signature was more difficult. This challenge was overcome with the help of detailed models of the triple-star system's light. Data from those models resulted in precise velocity measurements of the star circled by HD 188753 Ab. Note: The size of the Full-Res TIFF for the still image is 3200 samples x 2400 lines. |
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Circus Family of Stars (Arti
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PIA03521
Keck I Telescope
| Title |
Circus Family of Stars (Artist's Concept) |
| Original Caption Released with Image |
"" Quick Time Movie for PIA03521 Circus Family of Stars This artist's animation shows the clockwork-like orbits of a triple-star system called HD 188753, which was discovered to harbor a gas giant, or "hot Jupiter," planet. The planet zips around the system's main star (yellow, center) every 3.3 days, while the main star is circled every 25.7 years by a dancing duo of stars (yellow and orange, outer orbit). The star pair is locked in a 156-day orbit. This eccentric star family is a cramped bunch, the distance between the main star and the outer pair of stars is about the same as that between the Sun and Saturn. Though multiple-star systems like this one are common in the universe, astronomers were surprised to find a planet living in such tight quarters. One reason for the surprise has to do with theories of hot Jupiter formation. Astronomers believe that these planets begin life at the outer fringes of their stars, in thick dusty disks called protoplanetary disks, before migrating inward. The discovery of a world under three suns throws this theory into question. As seen in this animation, there is not much room at this system's outer edges for a hot Jupiter to grow. The discovery was made using the Keck I telescope atop Mauna Kea mountain in Hawaii. The triple-star system is located 149 light-years away in the constellation Cygnus. The sizes and orbital periods in the animation are not shown to scale. The relative motions are shown with respect to the main star. |
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Red-Hot Saturn
PIA07007
Sol (our sun)
Infrared Radiometer
| Title |
Red-Hot Saturn |
| Original Caption Released with Image |
These side-by-side false-color images show Saturn's heat emission. The data were taken on Feb. 4, 2004, from the W. M. Keck I Observatory, Mauna Kea, Hawaii. Both images were taken with infrared radiation. The image on the left was taken at a wavelength near 17.65 microns and is sensitive to temperatures in Saturn's upper troposphere. The image on the right was taken at a wavelength of 8 microns and is sensitive to temperatures in Saturn's stratosphere. The prominent hot spot at the bottom of each image is at Saturn's south pole. The warming of the southern hemisphere was expected, as Saturn was just past southern summer solstice, but the abrupt changes in temperature with latitude were not expected. The troposphere temperature increases toward the pole abruptly near 70 degrees latitude from 88 to 89 Kelvin (-301 to -299 degrees Fahrenheit) and then to 91 Kelvin (-296 degrees Fahrenheit) right at the pole. Near 70 degrees latitude, the stratospheric temperature increases even more abruptly from 146 to 150 Kelvin (-197 to -189 degrees Fahrenheit) and then again to 151 Kelvin (-188 degrees Fahrenheit) right at the pole. While the rings are too faint to be detected at 8 microns (right), they show up at 17.65 microns. The ring particles are orbiting Saturn to the left on the bottom and to the right on the top. The lower left ring is colder than the lower right ring, because the particles are just moving out of Saturn's shadow where they have cooled off. As they orbit Saturn, they warm up to a maximum just before passing behind Saturn again in shadow. |
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Saturn's Hot Spot
PIA07008
Sol (our sun)
Infrared Radiometer
| Title |
Saturn's Hot Spot |
| Original Caption Released with Image |
This is the sharpest image of Saturn's temperature emissions taken from the ground, it is a mosaic of 35 individual exposures made at the W.M. Keck I Observatory, Mauna Kea, Hawaii on Feb. 4, 2004. The images to create this mosaic were taken with infrared radiation. The mosaic was taken at a wavelength near 17.65 microns and is sensitive to temperatures in Saturn's upper troposphere. The prominent hot spot at the bottom of the image is right at Saturn's south pole. The warming of the southern hemisphere was expected, as Saturn was just past southern summer solstice, but the abrupt changes in temperature with latitude were not expected. The tropospheric temperature increases toward the pole abruptly near 70 degrees latitude from 88 to 89 Kelvin (-301 to -299 degrees Fahrenheit) and then to 91 Kelvin (-296 degrees Fahrenheit) right at the pole. Ring particles are not at a uniform temperature everywhere in their orbit around Saturn. The ring particles are orbiting clockwise in this image. Particles are coldest just after having cooled down in Saturn's shadow (lower left). As they orbit Saturn, the particles increase in temperature up to a maximum (lower right) just before passing behind Saturn again in shadow. A small section of the ring image is missing because of incomplete mosaic coverage during the observing sequence. |
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