GTC/OSIRIS Spectroscopic Identification of a Faint L Subdwarf in the UKIRT Infrared Deep Sky Survey

Lodieu, N.; Zapatero Osorio, M. R.; Martín, E. L.; Solano, E.; Aberasturi, M.
Bibliographical reference

The Astrophysical Journal Letters, Volume 708, Issue 2, pp. L107-L111 (2010).

Advertised on:
1
2010
Number of authors
5
IAC number of authors
1
Citations
32
Refereed citations
22
Description
We present the discovery of an L subdwarf in 234 deg2 common to the UK InfraRed Telescope (UKIRT) Infrared Deep Sky Survey Large Area Survey Data Release 2 and the Sloan Digital Sky Survey Data Release 3. This is the fifth L subdwarf announced to date, the first one identified in the UKIRT Infrared Deep Sky Survey, and the faintest known. The blue optical and near-infrared colors of ULAS J135058.86+081506.8 and its overall spectra energy distribution are similar to the known mid-L subdwarfs. Low-resolution optical (700-1000 nm) spectroscopy with the Optical System for Imaging and low Resolution Integrated Spectroscopy spectrograph on the 10.4 m Gran Telescopio de Canarias reveals that ULAS J135058.86+081506.8 exhibits a strong K I pressure-broadened line at 770 nm and a red slope longward of 800 nm, features characteristics of L-type dwarfs. From direct comparison with the four known L subdwarfs, we estimate its spectral type to be sdL4-sdL6 and derive a distance in the interval 94-170 pc. We provide a rough estimate of the space density for mid-L subdwarfs of 1.5 × 10-4 pc-3.