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News Release Archive:

News Release 421 of 948

December 9, 2004 01:00 PM (EST)

News Release Number: STScI-2004-33

Spitzer and Hubble Capture Evolving Planetary Systems

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Image: Disk of Debris Around Red Dwarf Star AU Microscopii

Disk of Debris Around Red Dwarf Star AU Microscopii

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ABOUT THIS IMAGE:

A visible-light image of a debris disk around the red dwarf star AU Microscopii. Planets may be forming, or might already exist, within it. The disk glows in starlight reflected by tiny grains of dust created by the collisions of asteroids and comets. Because it is composed of the pulverized remnants of these objects, it is called a "debris disk." More than 40 billion miles across, it appears like a spindle of light because we view it nearly edge on (like looking at a dinner plate along its side). The star is about 12 million years old and is only 32 light-years from Earth. This makes its disk the closest yet seen in reflected starlight. It is also the first disk imaged around an M-type red dwarf, the most common type of star in the stellar neighborhood around the Sun. The Hubble Space Telescope images, taken with the Advanced Camera for Surveys (ACS) reveal that the disk has been cleared of dust within about a billion miles of the star (first indicated from infrared-light measurements).

The ACS images confirm that the disk is warped and has small variations in dust density that, along with the central clearing, may be caused by the tugging of an unseen companion, perhaps a large planet. ACS shows that this is the only debris disk known that appears bluer than the star it surrounds. This may indicate that there are more small grains of dust, compared to large ones, than has been seen before in other such disks. Smaller grains scatter blue light better than red. The surplus of small grains may be due to the fact that the star is not bright enough to blow away these tiny particles. In brighter, hotter stars, the pressure from radiation can actually push small dust grains out of the disk and far out into space.

Object Names: AU Mic, GJ 803, HD197481

Image Type: Astronomical

Credit: NASA, ESA, J.E. Krist (STScI/JPL); D.R. Ardila (JHU); D.A. Golimowski (JHU); M. Clampin (NASA/Goddard); H.C. Ford (JHU); G.D. Illingworth (UCO-Lick); G.F. Hartig (STScI) and the ACS Science Team

NEWS RELEASE IMAGES

The above image is part of a montage:

Montage Image: Debris Disks Around Sun-Like Stars AU Microscopii and HD 107146 Image Type: Astronomical/Annotated Debris Disks Around Sun-Like Stars AU Microscopii and HD 107146PRC2004-33a Planetary Debris Disk Encircling Yellow Dwarf Star HD 107146 Image Type: Astronomical Planetary Debris Disk Encircling Yellow Dwarf Star HD 107146

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