2016AJ....151...46A


Query : 2016AJ....151...46A

2016AJ....151...46A - Astron. J., 151, 46 (2016/February-0)

Characterization of the very-low-mass secondary in the GJ 660.1AB system.

AGANZE C., BURGASSER A.J., FAHERTY J.K., CHOBAN C., ESCALA I., LOPEZ M.A., JIN Y., TAMIYA T., TALLIS M. and ROCKWARD W.

Abstract (from CDS):

We present a spectroscopic analysis of the low-mass binary star system GJ 660.1AB, a pair of nearby M dwarfs for which we have obtained separated near-infrared spectra (0.9-2.5 µm) with the SpeX spectrograph. The spectrum of GJ 660.1B is distinctly peculiar, with a triangular-shaped 1.7 µm peak that initially suggests that it is a low-surface-gravity, young brown dwarf. However, we rule out this hypothesis and determine instead that this companion is a mild subdwarf (d/sdM7) based on the subsolar metallicity of the primary, [Fe/H] = -0.63±0.06. Comparison of the near-infrared spectrum of GJ 660.1B to two sets of spectral models yields conflicting results, with a common effective temperature of Teff= 2550-2650 K, but alternately low surface gravity (log g = 4.4–0.5+0.5) and very low metallicity ([M/H] = -0.96–0.24+0.19), or high surface gravity (log g = 5.0-5.5) and slightly subsolar metallicity ([M/H] = -0.2–0.19+0.13). We conjecture that insufficient condensate opacity and excessive collision-induced H2 absorption in the models bias them toward low surface gravities and a metallicity that is inconsistent with the primary and points toward improvements needed in the spectral modeling of metal-poor, very-low-mass dwarfs. The peculiar spectral characteristics of GJ 660.1B emphasize that care is needed when interpreting surface gravity features in the spectra of ultracool dwarfs.

Abstract Copyright:

Journal keyword(s): brown dwarfs - stars: individual: (GJ 660.1A, GJ 660.1B) - stars: late-type - stars: low-mass

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

CDS comments: 2MASS J05341592-0631401 is a misprint for 2MASS J05341594-0631397.

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 2MASS J01151621+3130061 LM* 01 15 16.2849222123 +31 30 06.155566345           M8.5Ve 5 0
2 WISE J044853.28-193548.6 BD* 04 48 53.28216 -19 35 48.6672           T5pec 6 0
3 2MASS J05341594-0631397 PM* 05 34 15.9499381080 -06 31 39.804985488           M8p 7 0
4 APMPM J0559-2903 LM* 05 58 58.9230621580 -29 03 26.708741813       18.12 16.32 esdM7.5 22 0
5 HD 114762 SB* 13 12 19.7410686234 +17 31 01.630334317 7.78         F9VgF8mF4+M6?V 530 1
6 HD 114762B PM* 13 12 19.85 +17 31 04.5           M6?V 15 0
7 LP 440-52 LM* 14 39 00.3086540071 +18 39 38.710151529   19.6 18.39 17.3 14.64 sdM7 60 0
8 HD 148968 * 16 32 08.0838375024 -12 25 53.906470248   7.10 6.98     A0V 24 0
9 VB 8 Er* 16 55 35.2557374336 -08 23 40.753073075   18.7 16.916 14.566 12.24 M7Ve 415 0
10 G 19-16B LM* 17 12 51.2124829073 -05 07 25.429486239           d/sdM7 11 0
11 G 19-16 PM* 17 12 51.2720974378 -05 07 31.372615048 14.237 13.099 11.622 10.7 9.751 M1V 39 0
12 SIPS J2210-1952 PM* 22 10 49.9700195541 -19 52 25.851736422           M8Ve 12 0

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2022.12.06-08:18:22

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