2016A&A...589A..93D


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.12CEST23:39:38

2016A&A...589A..93D - Astronomy and Astrophysics, volume 589A, 93-93 (2016/5-1)

Measuring the extent of convective cores in low-mass stars using Kepler data: toward a calibration of core overshooting.

DEHEUVELS S., BRANDAO I., SILVA AGUIRRE V., BALLOT J., MICHEL E., CUNHA M.S., LEBRETON Y. and APPOURCHAUX T.

Abstract (from CDS):

Context.Our poor understanding of the boundaries of convective cores generates large uncertainties on the extent of these cores and thus on stellar ages. The detection and precise characterization of solar-like oscillations in hundreds of main-sequence stars by COROT andKepler has given the opportunity to revisit this problem. Aims.Our aim is to use asteroseismology to consistently measure the extent of convective cores in a sample of main-sequence stars whose masses lie around the mass limit for having a convective core.
Methods. We first tested and validated a seismic diagnostic that was proposed to probe the extent of convective cores in a model-dependent way using the so-called r010 ratios, which are built with l=0 and l=1 modes. We applied this procedure to 24 low-mass stars chosen amongKepler targets to optimize the efficiency of this diagnostic. For this purpose, we computed grids of stellar models with both the CESAM2K and MESA evolution codes, where the extensions of convective cores were modeled either by an instantaneous mixing or as a diffusion process.
Results. We found that 10 stars in our sample are in fact subgiants. Among the other targets, were able to unambiguously detect convective cores in eight stars, and we obtained seismic measurements of the extent of the mixed core in these targets with a good agreement between the CESAM2K and MESA codes. By performing optimizations using the Levenberg-Marquardt algorithm, we then obtained estimates of the amount of extra mixing beyond the core that is required in CESAM2K to reproduce seismic observations for these eight stars, and we showed that this can be used to propose a calibration of this quantity. This calibration depends on the prescription chosen for the extra mixing, but we found that it should also be valid for the codeMESA, provided the same prescription is used.
Conclusions. This study constitutes a first step toward calibrating the extension of convective cores in low-mass stars, which will help reduce the uncertainties on the ages of these stars.

Abstract Copyright: © ESO, 2016

Journal keyword(s): asteroseismology - convection - stars: evolution - stars: interiors

Simbad objects: 24

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Number of rows : 24

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 BD+47 2703 PM* 18 49 33.6588767037 +47 42 39.607284250   10.16 9.54     F9IV-V 36 0
2 HD 176153 Ro* 18 56 36.6478619140 +47 39 23.163197712   9.20 8.68     F9IV-V 65 0
3 HD 176693 Ro* 18 59 08.6846510375 +48 25 23.598982331   9.34 8.83     F8V 96 0
4 HD 177153 PM* 19 01 39.6781881955 +41 29 24.325583971   7.76 7.21     G0 88 0
5 TYC 3541-2345-1 * 19 02 09.8975762830 +45 16 39.354722755   10.90 10.21     G3V 31 0
6 HD 177412 ** 19 02 39.4182581022 +43 07 02.952679093   8.38 7.86     F6IV 44 0
7 BD+42 3247 PM* 19 06 58.3261704119 +42 26 08.264161006   10.32 9.75     G0.5IV 55 0
8 BD+39 3706 PM* 19 16 34.9029087477 +40 02 50.362111184       9.1   G1.5V 60 0
9 HD 234856 Ro* 19 17 45.8021284617 +50 28 48.273320177   9.87 9.32     F9IV-V 65 0
10 HD 181207 PM* 19 17 46.3566541779 +41 24 36.837551319   9.06 8.47     F9IV-V 72 0
11 BD+43 3221 * 19 20 47.9394314405 +44 09 18.749657280   10.03 9.50     F9IV-V 56 0
12 BD+43 3228 PM* 19 23 56.4114026497 +43 18 52.534860977   10.84 10.15     G0V 47 0
13 HD 182756 * 19 24 30.3488994710 +40 19 23.671169678   9.01 8.31     G1V 52 0
14 HD 183298 PM* 19 26 22.0908800928 +50 59 14.333199265   8.71 8.16     G0.5IV 76 0
15 TYC 3551-149-1 PM* 19 27 20.4902312930 +48 57 12.008653325   10.59 9.85     G5IV 43 0
16 TYC 3143-53-1 Ro* 19 35 03.7375425270 +42 44 16.720275774   10.31 9.85     F8IV 50 0
17 BD+44 3183 PM* 19 35 50.5740210502 +44 52 50.020113052   9.38 8.92     G0IV 46 0
18 TYC 3135-624-1 PM* 19 36 48.8136899967 +38 42 56.787490867   10.35 9.55     G5IV 59 0
19 TYC 3556-909-1 PM* 19 37 56.6968956803 +45 57 52.271767840   11.31 10.78     F5 35 0
20 TYC 3556-3445-1 Ro* 19 40 21.2108165107 +45 29 20.960913818   10.48 9.91     G3V 56 0
21 KOI-2720 Ro* 19 41 45.5179056932 +44 02 20.972241332   10.99 10.47     ~ 34 0
22 KOI-364 Ro* 19 43 29.3537343599 +42 52 52.080705146   10.81 10.13     G2.5IVa 49 0
23 HD 187637 PM* 19 49 18.1388420406 +41 34 56.857643338       7.2   F8V 86 0
24 HD 190166 PM* 20 01 51.4250664631 +44 21 14.146704965   10.13 9.58     F8V 42 0

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2020.07.12-23:39:38

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