J/A+A/579/A58 Spectra of two mid-L subdwarfs (Lodieu+, 2015)
A search for lithium in metal-poor L dwarfs.
Lodieu N., Burgasser A.J., Pavlenko Y., Rebolo R.
<Astron. Astrophys. 579, A58 (2015)>
=2015A&A...579A..58L 2015A&A...579A..58L
ADC_Keywords: Stars, subdwarf ; Spectroscopy
Keywords: techniques: spectroscopic - brown dwarfs - subdwarfs -
Abstract:
We obtained low- to intermediate-resolution (R∼2500-9000) optical
(∼560-770nm) spectra of two mid-L subdwarfs, SDSS J125637.13-022452.4
(SDSS1256; sdL3.5) and 2MASS J162620.14+392519.5 (2MASS1626; sdL4). 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.
Description:
Intermediate-resolution optical spectra of SDSS J125637.13-022452.4
and 2MASS J162620.14+392519.5 are provided. They have been obtained
with FORS2 on the ESO Very Large Telescope (grism GRIS1200R+93) and
OSIRIS on the Gran Telescopio de Canarias (grating R2500R),
respectively.
Objects:
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RA (ICRS) DE Designation(s)
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12 56 37.17 -02 24 52.2 SDSS J125637.13-022452.4 = 2MASS J12563716-0224522
16 26 20.14 +39 25 19.5 2MASS J16262014+3925195 = 2MASS J16262034+3925190
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
spec1256.dat 22 2048 VLT/FORS2 optical spectrum of SDSS1256
spec1626.dat 22 2051 GTC/OSIRIS optical spectrum of 2MASS1626
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See also:
J/PASP/118/659 : RI photometry of 2MASS late M and L dwarfs (Liebert+, 2006)
J/A+A/512/A37 : Velocities of 43 nearby L dwarfs (Seifahrt+, 2010)
J/A+A/564/A55 : 1.1-2.4um spectra of 7 young M & L dwarfs (Manjavacas+, 2014)
Byte-by-byte Description of file: spec1256.dat spec1626.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 nm lambda [560/770] Wavelength λ
11- 22 F12.9 cW/m2/nm Flux Flux (erg/cm2/s/Å)
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Acknowledgements:
Nicolas Lodieu, nlodieu(at)iac.es
(End) Nicolas Lodieu [IAC, Tenerife, Spain], Patricia Vannier [CDS] 04-Jun-2015