NOAO >   Observing Info >   Approved Programs >   2011B-0315

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Proposal Information for 2011B-0315


PI: You-Hua Chu, University of Illinois, yhchu@illinois.edu
Address: Astronomy Department, 1002 West Green Street, Urbana, Illinois 61801, USA

CoI: Jana Bilikova, University of Illinois
CoI: Robert Gruendl, University of Illinois
CoI: Andrew Riddle, University of Illinois
CoI: Kate Su, University of Arizona

Title: Completing the SEDs of Faint White Dwarfs with Mid-IR Excesses

Abstract: As intermediate- and low-mass stars lose mass to become white dwarfs (WDs), their planetary systems will expand and be dynamically rejuvenated with increased collisions among small bodies. The collisions generate dust that can be detected as IR excesses. Two types of dust disks around WDs are known: (1) small dust disks around cool DAZ/DBZ WDs produced by tidally disrupted asteroids, and (2) large dust disks around hot WDs produced by collisions among Kuiper Belt-like objects. Using the Spitzer archive, we have found serendipitous IRAC detections of ~280 WDs; ~60 of these show mid-IR excesses in at least one of the IRAC bands. The stellar temperatures and mid-IR excesses of some WDs suggest that their mid-IR excesses may originate from dust generated in ``Asteroid Belts''. About 2/3 of these WDs were not detected in the 2MASS survey. We request KPNO 2.1-m Flamingos JHK_s observations of these faint WDs with mid-IR excesses in order to complete their spectral energy distributions (SEDs), and characterize the origin of the mid-IR excesses. JHK_s observations are essential in revealing late-type companions and constraining the temperature and location of dust disks' inner edges. Our large sample of WDs with mid- IR excesses will allow a comprehensive investigation of evolution of planetary systems beyond the main sequence.


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