Discovery of Four High Proper Motion L Dwarfs, Including a 10 pc L Dwarf at the L/T Transition

Abstract

We discover four high proper motion L dwarfs by comparing the Wide-field Infrared Survey Explorer (WISE) to the Two Micron All Sky Survey (2MASS). WISE J140533.32+835030.5 is an L dwarf at the L/T transition with a proper motion of 0.85+/-0.02" yr^-1, previously overlooked due to its proximity to a bright star (V=12 mag). From optical spectroscopy we find a spectral type of L8, and from moderate-resolution J band spectroscopy we find a near-infrared spectral type of L9. We find WISE J140533.32+835030.5 to have a distance of 9.7+/-1.7 pc, bringing the number of L dwarfs at the L/T transition within 10 pc from six to seven. WISE J040137.21+284951.7, WISE J040418.01+412735.6, and WISE J062442.37+662625.6 are all early L dwarfs within 25 pc, and were classified using optical and low-resolution near-infrared spectra. WISE J040418.01+412735.6 is an L2 pec (red) dwarf, a member of the class of unusually red L dwarfs. We use follow-up optical and low-resolution near-infrared spectroscopy to classify a previously discovered (Castro & Gizis 2012) fifth object WISEP J060738.65+242953.4 as an (L8 Opt/L9 NIR), confirming it as an L dwarf at the L/T transition within 10 pc. WISEP J060738.65+242953.4 shows tentative CH_4 in the H band, possibly the result of unresolved binarity with an early T dwarf, a scenario not supported by binary spectral template fitting. If WISEP J060738.65+242953.4 is a single object, it represents the earliest onset of CH_4 in the H band of an L/T transition dwarf in the SpeX Library. As very late L dwarfs within 10 pc, WISE J140533.32+835030.5 and WISEP J060738.65+242953.4 will play a vital role in resolving outstanding issues at the L/T transition.

45 pages, 12 figures, accepted for publication in ApJ

References in corpus (15)

• The Second-Generation Guide Star Catalog: Description and Properties
• A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages
• Hubble Space Telescope NICMOS Observations of T Dwarfs: Brown Dwarf Multiplicity and New Probes of the L/T Transition
• Discovery of a Binary Brown Dwarf at 2 Parsecs from the Sun
• Subtle Signatures of Multiplicity in Late-type Dwarf Spectra: The Unresolved M8.5 + T5 Binary 2MASS J03202839-0446358
• Discovery of 11 New T Dwarfs in the Two Micron All-Sky Survey, Including a Possible L/T Transition Binary
• Discovery of Two Nearby, Peculiar L Dwarfs from the 2MASS Proper Motion Survey: Young or Metal-Rich?
• A search for binary systems among the nearest L dwarfs
• A Study of the Diverse T Dwarf Population Revealed by WISE
• Discovery of a T Dwarf Binary with the Largest Known J-Band Flux Reversal
• Resolved Near-Infrared Spectroscopy of WISE J104915.57-531906.1AB: A Flux-Reversal Binary at the L dwarf/T dwarf Transition
• Discovery of a High Proper Motion L Dwarf Binary: 2MASS J15200224-4422419AB
• SDSS J080531.84+481233.0: An Unresolved L Dwarf/T Dwarf Binary
• New M, L, and T Dwarf Companions to Nearby Stars from the Wide-field Infrared Survey Explorer
• Characterization of the Nearby L/T Binary Brown Dwarf WISE J104915.57-531906.1 at 2 Parsecs from the Sun

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