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

October 2013 • 2013ApJ...776..126C

Authors • Castro, Philip J. • Gizis, John E. • Harris, Hugh C. • Mace, Gregory N. • Kirkpatrick, J. Davy • McLean, Ian S. • Pattarakijwanich, Petchara • Skrutskie, Michael F.

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. 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 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 CH₄ 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 CH₄ 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2013ApJ...776..126C
• PDF https://stacks.iop.org/0004-637X/776/126/pdf
• PREPRINT http://arxiv.org/abs/1308.5252
• DATA https://irsa.ipac.caltech.edu/bibdata/2013/C/2013ApJ...776..126C.html
• ELECTR https://doi.org/10.1088%2F0004-637X%2F776%2F2%2F126