AAS 207th Meeting, 8-12 January 2006
Session 185 UV to IR Observations of Protostars
Poster, Thursday, 9:20am-4:00pm, January 12, 2006, Exhibit Hall

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[185.08] Rotation and Spitzer/IRAC fluxes in Orion

L. M. Rebull, J. R. Stauffer (SSC/JPL/Caltech), T. Megeath, J. Hora (CfA), L. Hartmann (U. Michigan)

Much effort has been expended in recent years in an effort to decipher the influence of circumstellar disks on rotation in pre-main-sequence stars. Early observations of TTauri stars suggested that stars with evidence of circumstellar accretion disks rotated slower than stars without such evidence. More recent observations have muddied the waters. Complicating this discussion, near-IR circumstellar disk indicators, though the most widely available, are subject to uncertainties that can result from inner disk holes and/or the system inclination. Mid-infrared observations are less sensitive to such effects, but until now, these observations have been difficult to obtain. The Spitzer Space Telescope now easily enables mid-infrared measurements of large samples of PMS stars covering a broad mass range in nearby star-forming regions. Megeath et al.\ (2005, in prep) surveyed the Orion Molecular Clouds (~3 Myr) with the IRAC instrument (3.6, 4.5, 5.8, 8 microns) as part of a joint IRAC and MIPS GTO program. In this contribution, we examine the relationship between rotation and Spitzer mid-IR fluxes for ~900 stars in Orion for stars between 3 and 0.1 Msun. We find in these Spitzer data the clearest indication to date that stars with longer periods are more likely than those with short periods to have IR excesses suggestive of disks.

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