Ultracool field brown dwarf candidates selected at 4.5 microm

P Eisenhardt, Roger L Griffith, Daniel Stern, E L Wright, M L N Ashby, Mark Brodwin, Michael Brown, Shane Bussmann, Arjun Dey, A M Ghez, Eilat Glikman, Anthony H Gonzalez, J Davy Kirkpatrick, Quinn Konopacky, A Mainzer, David Vollbach, Shelley A Wright

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    We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] = 1.5 and [4.5] - [8.0] 70 pc. The reddest brown dwarf candidate (SDWFS J143356.62+351849.2) has [3.6] - [4.5] = 2.24 and H - [4.5] > 5.7, redder than any published brown dwarf in these colors, and may be the first example of the elusive Y-dwarf spectral class. Models from Burrows et al. predict that larger numbers of cool brown dwarfs should be found for a Chabrier mass function. Suppressing the model [4.5] flux by a factor of 2, as indicated by previous work, brings the Burrows models and observations into reasonable agreement. The recently launched Wide-field Infrared Survey Explorer will probe a volume similar to 40x larger and should find hundreds of brown dwarfs cooler than T7.
    Original languageEnglish
    Pages (from-to)2455 - 2464
    Number of pages9
    JournalThe Astronomical Journal
    Issue number6
    Publication statusPublished - 2010

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