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Published June 2006 | Published
Journal Article Open

A Large-Area Search for Low-Mass Objects in Upper Scorpius. I. The Photometric Campaign and New Brown Dwarfs


We present a wide-field photometric survey covering ~200 deg^2 toward the Upper Scorpius OB association. Data taken in the R and I bands with the Quest-2 camera on the Palomar 48 inch (1.2 m) telescope were combined with the Two Micron All Sky Survey JHK_S survey and used to select candidate pre-main-sequence stars. Follow-up spectroscopy with the Palomar 200 inch (5.1 m) telescope of 62 candidate late-type members identified 43 stars that have surface gravity signatures consistent with association membership. From the optical/near-infrared photometry and derived spectral types we construct an H-R diagram for the new members and find 30 likely new brown dwarfs, nearly doubling the known substellar population of the Upper Scorpius OB association. Continuation of our spectroscopic campaign should reveal hundreds of new stellar and substellar members.

Additional Information

© 2006 The American Astronomical Society. Received 2005 December 24; accepted 2006 February 14. The authors would like to thank the entire Quest-2 collaboration and in particular David Rabinowitz, Anne Bauer, Jonathan Jerke, and Adam Rengstorf for observing and processing the photometric drift-scan data. We are appreciative to Ashish Mahabal and Milan Bogosavljevic for their help in understanding the Quest-2 systematics. We thank Russel White and David Ardila for discussions and insights that helped in our analysis.

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Published - SLEaj06a.pdf


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