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VEGA of Goddard Space Flight Center (GSFC) and Hawaii
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Three Dusty Stars
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Three Dusty Stars |
| Explanation |
These separate radio images [ http://www.jach.hawaii.edu/~wsh/press/dustydisks.html ] reveal three dusty debris disks [ http://www.jach.hawaii.edu/~wsh/press/images.html ] surrounding three bright, young, nearby stars - evidence for solar systems [ http://wwwusr.obspm.fr/departement/darc/planets/encycl.html ] in formation. From left to right are the stars Fomalhaut [ http://www.astro.wisc.edu/~dolan/constellations/hr/8728.html ], Beta Pictoris [ http://antwrp.gsfc.nasa.gov/apod/ap980122.html ], and Vega [ http://antwrp.gsfc.nasa.gov/apod/ap970715.html ], their positions indicated by star symbols. The false color maps show the intensity of submillimeter radio emission from the surrounding dust. Next to each dust "disk", a vertical bar illustrates the present size of our own solar system. These observations are likely examples of what our solar system [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ] would have looked like to distant radio astronomers [ http://www.seti-inst.edu/phoenix/contact.html ] when it was only a few hundred million years old! Astronomers speculate that bright blobs of emission near Vega and Beta Pictoris may represent dust clouds around developing giant planets. The radio images were made using detectors [ http://www.jach.hawaii.edu/JCMT/scuba/ ] cooled to near absolute zero [ http://www.unidata.ucar.edu/staff/blynds/tmp.html ] and the James Clerk Maxwell Telescope [ http://www.jach.hawaii.edu/JCMT/home.html ] at Mauna Kea Observatory in Hawaii [ http://antwrp.gsfc.nasa.gov/apod/ap970302.html ]. |
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HR 4796A: Not Saturn
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HR 4796A: Not Saturn |
| Explanation |
These are not false-color renderings of the latest observations of Saturn's magnificent rings [ http://antwrp.gsfc.nasa.gov/apod/ap980424.html ]. Instead, the panels show a strikingly similar system on a much larger scale - a ring around the young, Vega-like star, HR 4796A [ http://oposite.stsci.edu/pubinfo/pr/1999/03/b.html ], located about 200 light-years from Earth. Probably composed of dusty debris ground from colliding planetesimals, this ring is confined to a zone less than 17 AU wide (1 AU equals the Earth-Sun distance) and girdles the star at a radius of about 70 AU, roughly twice the orbital radius of Neptune. In analogy with the relationship of Saturn's rings and moons [ http://ringmaster.arc.nasa.gov/reference/abstracts/cuzzi1984_01.html ], this circumstellar ring could be held in place by forces due to planets - shepherding planetary bodies or the gravitational influence of larger planets orbiting closer to the parent star. In any event, because the ring would not survive long without something to keep it there, astronomers consider its presence strong evidence for unseen planetary bodies [ http://www.generation.net/~mariob/astro/xtrasol.htm ] around HR 4796A. The top panels show the false-color images [ http://nicmosis.as.arizona.edu:8000/AAS99/hr4796_postrev5.ps ] at two infrared wavelengths from the Hubble Space Telescope's NICMOS instrument [ http://nicmos.as.arizona.edu/ ], and the bottom panels trace the corresponding image contours. At the center of each, the overwhelming light of HR 4796A has been masked to reveal the fainter circumstellar ring. |
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