Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4

Details Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4 Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4

2009-03-09

arxiv.org/abs/0903.1567v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

19 pages, 6 figures, accepted for publication to Astrophysical Journal

Scientific paper

10.1088/0004-637X/697/1/148

Red optical and near-infrared spectroscopy are presented for SDSS J125637.13-022452.4, one of only four L subdwarfs reported to date. These data confirm the low-temperature, metal-poor nature of this source, as indicated by prominent metal-hydride bands, alkali lines, and collision-induced H2 absorption. The optical and near-infrared spectra of SDSS J1256-0224 are similar to those of the sdL4 2MASS J16262034+3925190, and we derive a classification of sdL3.5 based on the preliminary scheme of Burgasser, Cruz, & Kirkpatrick. The kinematics of SDSS J1256-0224 are consistent with membership in the Galactic inner halo, with estimated $UVW$ space velocities indicating a slightly prograde, eccentric and inclined Galactic orbit (3.5 <~ R <~ 11 kpc; |Zmax| = 7.5 kpc). Comparison to synthetic spectra computed with the Phoenix code, including the recent implementation of kinetic condensate formation (Drift-Phoenix), indicate Teff ~ 2100-2500 K and [M/H] ~ -1.5 to -1.0 for logg ~ 5.0-5.5 (cgs), although there are clear discrepancies between model and observed spectra particularly in the red optical region. The stronger metal-oxide bands present in the Drift-Phoenix model spectra, a result of phase-non-equilibrium abundances of grain species, appears to contradict prior suggestions that grain formation is inhibited in metal-poor atmospheres; conclusive statements on the metallicity dependence of grain formation efficiency are as yet premature. In addition, an apparent shift in the temperature scale of L subdwarfs relative to L dwarfs may obviate the need for modified grain chemistry to explain some of the former's unique spectral characteristics.

Affiliated with

Also associated with

No associations

Rating

Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical and Near-Infrared Spectroscopy of the L Subdwarf SDSS J125637.13-022452.4 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-95940