SIMBAD references

2017ApJ...838...73M - Astrophys. J., 838, 73-73 (2017/March-3)

Surface gravities for 228 M, L, and T dwarfs in the NIRSPEC Brown Dwarf Spectroscopic Survey.

MARTIN E.C., MACE G.N., McLEAN I.S., LOGSDON S.E., RICE E.L., KIRKPATRICK J.D., BURGASSER A.J., McGOVERN M.R. and PRATO L.

Abstract (from CDS):

We combine 131 new medium-resolution (R ∼ 2000) J-band spectra of M, L, and T dwarfs from the Keck NIRSPEC Brown Dwarf Spectroscopic Survey (BDSS) with 97 previously published BDSS spectra to study surface-gravity-sensitive indices for 228 low-mass stars and brown dwarfs spanning spectral types M5-T9. Specifically, we use an established set of spectral indices to determine surface gravity classifications for all of the M6-L7 objects in our sample by measuring the equivalent widths (EW) of the K I lines at 1.1692, 1.1778, and 1.2529 µm, and the 1.2 µm FeHJ absorption index. Our results are consistent with previous surface gravity measurements, showing a distinct double peak-at ∼L5 and T5-in K I EW as a function of spectral type. We analyze the K I EWs of 73 objects of known ages and find a linear trend between log(Age) and EW. From this relationship, we assign age ranges to the very low gravity, intermediate gravity, and field gravity designations for spectral types M6-L0. Interestingly, the ages probed by these designations remain broad, change with spectral type, and depend on the gravity-sensitive index used. Gravity designations are useful indicators of the possibility of youth, but current data sets cannot be used to provide a precise age estimate.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): brown dwarfs - infrared: stars - stars: atmospheres - stars: low-mass - surveys - surveys

VizieR on-line data: <Available at CDS (J/ApJ/838/73): table1.dat table2.dat table3.dat refs.dat>

Simbad objects: 233

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2020.01.26-07:17:17

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