The Role of Multiplicity in Protoplanetary Disk Evolution
First Author:
Adam Kraus
Email: alk AT astro.caltech.edu
Caltech
1200 E. California Blvd, MC 105-24
Pasadena, CA, 91125, USA
Coauthors:
Ireland, Michael, University of Sydney
Martinache, Frantz, Cornell
Lloyd, James, Cornell
Hillenbrand, Lynne, Caltech
Abstract
Interactions with close stellar or planetary companions can significantly influence the evolution and lifetime of protoplanetary disks. It has recently become possible to search for these companions, directly studying the role of multiplicity in protoplanetary disk evolution. I will describe an ongoing survey to directly detect these stellar and planetary companions in nearby star-forming regions. This survey uses adaptive optics and sparse aperture masking to achieve typical contrast limits of DeltaK=5-6 at the diffraction limit (5-8 MJup at 5-30 AU), while also detecting similar-flux binary companions at separations as low as 15 mas (2.5 AU). Aside from the new binary system CoKu Tau/4, our survey has found no evidence of companions (planetary or binary) among the well-known "transitional disk" systems; if the inner clearings are due to planet formation, as has been previously suggested, then this paucity places an upper limit on the mass of any resulting planet. Our survey also has uncovered many new binary systems, with a majority falling among the diskless (WTTS) population. This disparity suggests that disk evolution for close (5-30 AU) binary systems is very different than for single stars; most circumbinary disks are cleared by ages of 1-2 Myr, while most circumstellar disks are not. These diskless binary systems have biased the disk frequency downward in previous studies; if we remove our new systems from those samples, we find that the disk fraction for single stars could be higher than was previously suggested.
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