2015A&A...579A..58L


Query : 2015A&A...579A..58L

2015A&A...579A..58L - Astronomy and Astrophysics, volume 579A, 58-58 (2015/7-1)

A search for lithium in metal-poor L dwarfs.

LODIEU N., BURGASSER A.J., PAVLENKO Y. and REBOLO R.

Abstract (from CDS):

The aim of the project is to search for lithium in absorption at 6707.8 Å to constrain the nature and mass of the brightest low-metallicity L-type dwarfs (referred to as L subdwarfs) identified in large-scale surveys. We obtained low- to intermediate-resolution (R∼2500-9000) optical (∼560-770nm) spectra of two mid-L subdwarfs, SDSSJ125637.13-022452.4 (SDSS1256; sdL3.5) and 2MASSJ162620.14+392519.5 (2MASS1626; sdL4) with spectrographs on the European Southern Observatory Very Large Telescope and the Gran Telescopio de Canarias. We report the presence of a feature at the nominal position of the lithium absorption doublet at 6707.8Å in the spectrum of SDSS1256, with an equivalent width of 66±27Å at 2.4σ, which we identify as arising from a CaH molecular transition based on atmosphere models. We do not see any feature at the position of the lithium feature in the spectrum of 2MASS1626. The existence of overlapping molecular absorption sets a confusion detection limit of [Li/H]=-3 for equivalently typed L subdwarfs. We provided improved radial velocity measurements of -126±10km/s and -239±12km/s for SDSS1256 and 2MASS1626, respectively, as well as revised Galactic orbits. We implemented adjusting factors for the CaH molecule in combination with the NextGen atmosphere models to fit the optical spectrum of SDSS1256 in the 6200-7300Å range. We also estimate the expected Li abundance from interstellar accretion ([Li/H]=-5), place limits on circumstellar accretion (109g/yr), and discuss the prospects of Li searches in cooler L and T subdwarfs.

Abstract Copyright:

Journal keyword(s): techniques: spectroscopic - brown dwarfs - subdwarfs

VizieR on-line data: <Available at CDS (J/A+A/579/A58): spec1256.dat spec1626.dat>

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 BD+52 913 WD* 05 05 30.6180977592 +52 49 51.919301604 10.25 11.44 11.69 11.93 12.108 DA.8 1089 0
2 2MASS J05325346+8246465 BD* 05 32 54.4345118405 +82 46 45.161005926           esdL7 61 0
3 HD 42581B BD* 06 10 34.80 -21 52 00.0           T6.5 504 0
4 2MASS J06164006-6407194 BD* 06 16 40.06 -64 07 19.5           sdL5 17 0
5 2MASS J06453153-6646120 BD* 06 45 31.53216 -66 46 12.0432           sdL8 8 0
6 Wolf 359 Er* 10 56 28.9208702274 +07 00 53.003285286 16.706 15.541 13.507 11.684 9.507 dM6 719 0
7 2MASS J12563716-0224522 BD* 12 56 37.1377931858 -02 24 52.266257764           esdL3.5 40 0
8 CD-28 11464 Pe* 15 38 59.6479538952 -28 35 36.973634856   12.310 11.797 11.794   A 116 0
9 2MASS J16262034+3925190 BD* 16 26 20.1332795396 +39 25 19.488610341       19.67 16.68 esdL4 51 0
10 Ross 640 WD* 16 28 25.0030896166 +36 46 15.846877416   14.01   13.9   DZ6 204 0
11 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 14383 0
12 CD-44 12736 PM* 18 36 25.9502475648 -44 18 36.907592904   10.83 10.22     G0 211 0
13 * eps Ind B BD* 22 04 10.5951812451 -56 46 58.239102418     24.12 20.8 15.60 T1V+T6V 161 1
14 NAME Galactic Bar reg ~ ~           ~ 1215 0
15 NAME Galactic Bulge reg ~ ~           ~ 4290 0

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