Primeval very low-mass stars and brown dwarfs. I. Six new L subdwarfs, classification and atmospheric properties

Z. H. Zhang, D. J. Pinfield, M. C. Galvez-Ortiz, B. Burningham, N. Lodieu, F. Marocco, A. J. Burgasser, A. C. Day-Jones, F. Allard, H. R. A. Jones, D. Homeier, J. Gomes, R. L. Smart

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We have conducted a search for L subdwarf candidates within the photometric catalogues of the UKIRT Infrared Deep Sky Survey and Sloan Digital Sky Survey. Six of our candidates are confirmed as L subdwarfs spectroscopically at optical and/or near infrared wavelengths. We also present new optical spectra of three previously known L subdwarfs (WISEA J001450.17-083823.4, 2MASS J00412179+3547133, ULAS J124425.75+102439.3). We examined the spectral types and metallicity subclasses classification of known L subdwarfs. We summarised the spectroscopic properties of L subdwarfs with different spectral types and subclasses. We classify these new L subdwarfs by comparing their spectra to known L subdwarfs and L dwarf standards. We estimate temperatures and metallicities of 22 late type M and L subdwarfs by comparing their spectra to BT-Settl models. We find that L subdwarfs have temperatures between 1500 K and 2700 K, which are higher than similarly-typed L dwarfs by around 100-400 K depending on different subclasses and subtypes. We constrained the metallicity ranges of subclasses of M, L and T subdwarfs. We also discussed the spectral type and absolute magnitude relationships for L and T subdwarfs.
Original languageEnglish
Pages (from-to)3040-3059
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date26 Sept 2016
Publication statusPublished - 1 Jan 2017


  • brown dwarfs
  • stars: chemically peculiar
  • stars: individual: ULAS j021642+004005.6, ULAS j124947.04+095019.8, SDSS J133348.24+273508.8, ULAS J133836.97-022910.7, SDSS J134749.74+333601.7, ULAS J151913.03-000030.0
  • stars: low mass
  • stars: Population II
  • Subdwarfs


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