2023A&A...671A.119C


Query : 2023A&A...671A.119C

2023A&A...671A.119C - Astronomy and Astrophysics, volume 671A, 119 (2023/3-1)

Impact of a new H/He equation of state on the evolution of massive brown dwarfs New determination of the hydrogen burning limit.

CHABRIER G., BARAFFE I., PHILLIPS M. and DEBRAS F.

Abstract (from CDS):

We explored the impact of the latest equation of state (EOS) for dense hydrogen-helium mixtures, which takes into account the interactions between hydrogen and helium species during the evolution of very low-mass stars and brown dwarfs (BDs). These interactions modify the thermodynamic properties of the H/He mixture, notably the entropy, a quantity of prime importance for these fully convective bodies, but also the onset and the development of degeneracy throughout the body. This translates into a faster cooling rate, that is, cooler isentropes for a given mass and age, and thus larger BD masses and smaller radii for a given effective temperature and luminosity than the models based on previous EOSs. This means that objects of a given mass and age in the range M ≲ 0.1 M, τ ≳ 108 yr will have cooler effective temperatures and fainter luminosities. Confronting these new models with several observationally determined BD dynamical masses, we show that this improves the agreement between evolutionary models and observations and resolves at least part of the observed discrepancy between the properties of dynamical mass determinations and evolutionary models. A noticeable consequence of this improvement of the dense H/He EOS is that it yields a larger H-burning minimum mass, now found to be 0.075 M (78.5 MJup) with the ATMO atmosphere models for solar metallicity. These updated BD models are made publicly available.

Abstract Copyright: © The Authors 2023

Journal keyword(s): dense matter - equation of state - stars: low-mass - brown dwarfs

Simbad objects: 15

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Number of rows : 15
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 2MASS J00345157+0523050 BD* 00 34 51.57696 +05 23 05.0964           T6.5 34 0
2 HD 4113C BD* 00 43 12.59 -37 58 57.4           T9 23 0
3 HD 4747 SB* 00 49 26.7604733944 -23 12 44.868742449 8.244 7.927 7.155 6.732 6.344 G8/K0V 189 0
4 HD 19467B BD* 03 07 18.48 -13 45 43.3           T5.5+1 42 0
5 HD 42581B BD* 06 10 34.80 -21 52 00.0           T6.5 505 0
6 NAME Scholz's star LM* 07 20 03.25368 -08 46 49.9044   19.9   16.9 13.80 M9.5+T5 54 0
7 2MASS J08053189+4812330 BD* 08 05 31.8496436040 +48 12 33.131831320           L4+T5 42 0
8 2MASS J10595138-2113082 BD* 10 59 51.4028549640 -21 13 08.574097512       20.237 17.974 L2.8:V 14 0
9 2MASSI J1534498-295227 BD* 15 34 49.84080 -29 52 27.4188           T4.5+T5 66 0
10 HD 182488B BD* 19 23 34.0126 +33 13 19.078           T9 69 0
11 HD 182488 PM* 19 23 34.0131683760 +33 13 19.078425912       5.8   K0V 280 1
12 * 15 Sge B BD* 20 04 06.2 +17 04 13           L4-5 55 0
13 * eps Ind PM* 22 03 21.6536261624 -56 47 09.522795714   5.75 4.69     K5V 553 0
14 * eps Ind B BD* 22 04 10.5951812451 -56 46 58.239102418     24.12 20.8 15.60 T1V+T6V 163 1
15 2MASS J22521073-1730134 BD* 22 52 10.7512306563 -17 30 13.889743018         17.9 L4.5+T3.5 56 0

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