AAS 207th Meeting, 8-12 January 2006
Session 63 From Here to Eternity: The Spitzer Legacy Programs
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[63.11] Spitzer Space Telescope Observations of the Pleiades: Debris Disks and Brown Dwarfs

J.R. Stauffer, L.M. Rebull (Spitzer Science Center), D.E. Backman (Ames Research Center), J.M. Carpenter, L.A. Hillenbrand (Caltech), M.R. Meyer, D.C. Hines (Steward Observatory), S. Ramirez (IPAC), P. Lowrance (Spitzer Science Center), G.G. Fazio (Smithsonian Astrophysical Observatory), FEPS Collaboration, IRAC GTO Team

Fluxes and upper limits in the wavelength range from 3.6 to 70 microns from the Spitzer Space Telescope are provided for twenty solar-mass Pleiades members as part of the FEPS (Formation and Evolution of Planetary Systems) Spitzer Legacy program.. One of these stars shows a probable mid-IR excess and two others have possible excesses, presumably due to circumstellar debris disks. For the star with the largest, most secure excess flux at MIPS wavelengths, HII1101, we derive Log(Ldust/L*) ~ -3.8 and an estimated debris disk mass of 4.2 x 10-5 M(Earth) for an assumed uniform dust grain size of 10 microns. If the stars with detected excesses are interpreted as stars with relatively recent, large collision events producing a transient excess of small dust particles, the frequency of such disk transients is about ~10% for our ~100 Myr, Pleiades G dwarf sample. For the stars without detected 24-70 micron excesses, the upper limits to their fluxes correspond to approximate 3 sigma upper limits to their disk masses of 6 x 10-6 M(Earth) using the MIPS 24 micron upper limit, or 2 x 10-4 M(Earth) using the MIPS 70 micron limit.

We also have obtained deep IRAC imaging of a portion of the Pleiades in order to search for very low mass members. We will report initial analysis of that dataset.

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