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Discovery of Brown Dwarfs With Virtual Observatories : Why Get Excited Over One Brown Dwarf?

http://www.us-vo.org. Discovery of Brown Dwarfs With Virtual Observatories : Why Get Excited Over One Brown Dwarf? G. Bruce Berriman (IPAC, Caltech) J. Davy Kirkpatrick (IPAC, Caltech) Robert  Hanisch (STScI) Alex  Szalay (JHU) Roy  Williams (CACR, Caltech).

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Discovery of Brown Dwarfs With Virtual Observatories : Why Get Excited Over One Brown Dwarf?

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  1. http://www.us-vo.org Discovery of Brown Dwarfs With Virtual Observatories : Why Get Excited Over One Brown Dwarf? G. Bruce Berriman (IPAC, Caltech) J. Davy Kirkpatrick (IPAC, Caltech) Robert  Hanisch (STScI) Alex  Szalay (JHU) Roy  Williams(CACR, Caltech) JD08: Large Telescopes and Virtual Observatories

  2. Science Driver for Brown Dwarf Search • Purpose of pilot study • Cross-match 2MASS & SDSS to find candidate brown dwarfs that are cooler and more distant (>12pc) than either survey alone can reliably find. • History • 2MASS and SDSS have revolutionized our knowledge of the coolest “stellar” spectral types, L and T. Mid-T dwarfs detected out to ~12pc. • Beyond these limits, SDSS-detected T dwarfs become z’-only detections. • Most z’-only detections from SDSS are unreliable (Fan et al. 2001). • Similarly, cooler T dwarfs are expected to become J-only detections in 2MASS. • Most J-only detections from 2MASS are unreliable (Burgasser 2001). JD08: Large Telescopes and Virtual Observatories

  3. As a T dwarf becomes cooler (i.e., methane and water absorptions increase) or more distant… • SDSS detects it only at z’ band • 2MASS detects it only at J band JD08: Large Telescopes and Virtual Observatories

  4. What is the Best Way to Cross-Match Large Catalogs? • Cross-matching is I/O intensive  performance is severely bandwidth limited • Cross-matching best performed by replicating remote data sets at one site cf. Cross-matching over a network. • 10,225,897 SDSS EDR sources & 454,516 2MASS 2IDR sources • 90 seconds locally vs. 13,500 seconds over 100 Mbits/second network JD08: Large Telescopes and Virtual Observatories

  5. Cross-Match Statistics • 326,020 cross-matched candidate pairs in the 2MASS IDR2 and SDSS EDR overlap (~150 sq deg; ~0.4% of sky) • 2889 objects with z-J>2.75  late-L to T dwarf candidates with separations of <3” • Nine with separations of <1.0" and i-z colors of >1.0. • Two are known brown dwarfs • Four were likely spurious detections • Three are new candidate brown dwarfs JD08: Large Telescopes and Virtual Observatories

  6. Brown Dwarfs & Candidates JD08: Large Telescopes and Virtual Observatories

  7. 2MASS 0104-0053 The Wee Broon Beastie KS J H JD08: Large Telescopes and Virtual Observatories

  8. Keck LRIS Spectrum of 2MASSI J0104075-005328 JD08: Large Telescopes and Virtual Observatories

  9. The Next Step: Sloan DR1 vs. 2MASS All Sky Both Surveys publicly released Spring2003 DR1 covers 2099 square degrees 53,000, 000 objects Sloan DR1 - Imaging Sky Coverage Larger area gives us much better chance of finding cooler objects, not just more distant ones JD08: Large Telescopes and Virtual Observatories

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