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dc.contributor.authorMarocco, F.
dc.contributor.authorJones, H.R.A.
dc.contributor.authorDay-Jones, A. C.
dc.contributor.authorPinfield, D.J.
dc.contributor.authorLucas, P.W.
dc.contributor.authorBurningham, B.
dc.contributor.authorZhang, Z. H.
dc.contributor.authorSmart, R.L.
dc.contributor.authorGomes, J. I.
dc.contributor.authorSmith, L.
dc.date.accessioned2015-06-03T13:36:09Z
dc.date.available2015-06-03T13:36:09Z
dc.date.issued2015-06-01
dc.identifier.citationMarocco , F , Jones , H R A , Day-Jones , A C , Pinfield , D J , Lucas , P W , Burningham , B , Zhang , Z H , Smart , R L , Gomes , J I & Smith , L 2015 , ' A large spectroscopic sample of L and T dwarfs from UKIDSS LAS : peculiar objects, binaries, and space density ' , Monthly Notices of the Royal Astronomical Society , vol. 449 , no. 4 , pp. 3651-3692 . https://doi.org/10.1093/mnras/stv530
dc.identifier.issn0035-8711
dc.identifier.otherArXiv: http://arxiv.org/abs/1503.05082v1
dc.identifier.otherORCID: /0000-0002-8872-4462/work/62748960
dc.identifier.otherORCID: /0000-0003-4600-5627/work/64327366
dc.identifier.urihttp://hdl.handle.net/2299/15996
dc.descriptionThis is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record [F. Marocco, et al, 'A large spectroscopic sample of L and T dwarfs from UKIDSS LAS: peculiar objects, binaries, and space density', MNRAS, Vol. 449)4): 3651-3692, April 2015] is available online at: https://doi.org/10.1093/mnras/stv530.
dc.description.abstractWe present the spectroscopic analysis of a large sample of late-M, L, and T dwarfs from UKIDSS. Using the YJHK photometry from ULAS and the red-optical photometry from SDSS we selected a sample of 262 brown dwarf candidates and we followed-up 196 of them using X-shooter on the VLT. The large wavelength coverage (0.30-2.48 $\mu$m) and moderate resolution (R~5000-9000) of X-shooter allowed us to identify peculiar objects including 22 blue L dwarfs, 2 blue T dwarfs, and 2 low gravity M dwarfs. Using a spectral indices-based technique we identified 27 unresolved binary candidates, for which we determined the spectral type of the potential components via spectral deconvolution. The spectra allowed us to measure the equivalent width of the prominent absorption features and to compare them to atmospheric models. Cross-correlating the spectra with a radial velocity standard, we measured the radial velocity for our targets, and we determined the distribution of the sample, which is centred at -1.7$\pm$1.2 km s$^{-1}$ with a dispersion of 31.5 km s$^{-1}$. Using our results we estimated the space density of field brown dwarfs and compared it with the results of numerical simulations. Depending on the binary fraction, we found that there are (0.85$\pm$0.55) x 10$^{-3}$ to (1.00$\pm$0.64) x 10$^{-3}$ objects per cubic parsec in the L4-L6.5 range, (0.73$\pm$0.47) x 10$^{-3}$ to (0.85$\pm$0.55) x 10$^{-3}$ objects per cubic parsec in the L7-T0.5 range, and (0.74$\pm$0.48) x 10$^{-3}$ to (0.88$\pm$0.56) x 10$^{-3}$ objects per cubic parsec in the T1-T4.5 range. There seem to be an excess of objects in the L/T transition with respect to the late T dwarfs, a discrepancy that could be explained assuming a higher binary fraction than expected for the L/T transition, or that objects in the high-mass end and low-mass end of this regime form in different environments, i.e. following different IMFs.en
dc.format.extent3494639
dc.language.isoeng
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.subjectastro-ph.SR
dc.titleA large spectroscopic sample of L and T dwarfs from UKIDSS LAS : peculiar objects, binaries, and space densityen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
rioxxterms.versionofrecord10.1093/mnras/stv530
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


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