2019A&A...627A.173V


Query : 2019A&A...627A.173V

2019A&A...627A.173V - Astronomy and Astrophysics, volume 627A, 173-173 (2019/7-2)

Masses and ages for metal-poor stars. A pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars.

VALENTINI M., CHIAPPINI C., BOSSINI D., MIGLIO A., DAVIES G.R., MOSSER B., ELSWORTH Y.P., MATHUR S., GARCIA R.A., GIRARDI L., RODRIGUES T.S., STEINMETZ M. and VALLENARI A.

Abstract (from CDS):

Context. Very metal-poor halo stars are the best candidates for being among the oldest objects in our Galaxy. Samples of halo stars with age determination and detailed chemical composition measurements provide key information for constraining the nature of the first stellar generations and the nucleosynthesis in the metal-poor regime. Aims. Age estimates are very uncertain and are available for only a small number of metal-poor stars. We present the first results of a pilot programme aimed at deriving precise masses, ages, and chemical abundances for metal-poor halo giants using asteroseismology and high-resolution spectroscopy. Methods. We obtained high-resolution UVES spectra for four metal-poor RAVE stars observed by the K2 satellite. Seismic data obtained from K2 light curves helped improve spectroscopic temperatures, metallicities, and individual chemical abundances. Mass and ages were derived using the code PARAM, investigating the effects of different assumptions (e.g. mass loss and [α/Fe]-enhancement). Orbits were computed using Gaia DR2 data. Results. The stars are found to be normal metal-poor halo stars (i.e. non C-enhanced), and an abundance pattern typical of old stars (i.e. α and Eu-enhanced), and have masses in the 0.80-1.0M range. The inferred model-dependent stellar ages are found to range from 7.4Gyr to 13.0Gyr with uncertainties of ∼30%-35%. We also provide revised masses and ages for metal-poor stars with Kepler seismic data from the APOGEE survey and a set of M4 stars.Conclusions. The present work shows that the combination of asteroseismology and high-resolution spectroscopy provides precise ages in the metal-poor regime. Most of the stars analysed in the present work (covering the metallicity range of [Fe/H]~-0.8 to -2dex) are very old >9Gyr (14 out of 19 stars), and all of the stars are older than >5Gyr (within the 68 percentile confidence level).

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: fundamental parameters - asteroseismology - stars: abundances

VizieR on-line data: <Available at CDS (J/A+A/627/A173): table4.dat tableb1.dat linelist.dat>

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 - 2023
#notes
1 BD-16 251 RG* 01 29 31.1311443552 -16 00 45.495314460 12.527 12.427 11.642 11.189 10.713 CEMP 283 0
2 TYC 4932-571-1 SB* 11 54 36.1315766256 -01 33 45.130256460   12.107 11.242 11.02   ~ 9 0
3 NGC 6121 424 RG* 16 23 16.9017005856 -26 29 47.955475500 15.28 14.389 13.100   11.559 ~ 20 0
4 Cl* NGC 6121 MVP 33946 RG* 16 23 21.9541703184 -26 30 32.055462756 15.63 14.878 13.643   12.148 ~ 14 0
5 NGC 6121 35 RG* 16 23 24.0238740192 -26 30 00.551004264 15.17 14.128 12.776   11.162 ~ 17 0
6 NGC 6121 361 RG* 16 23 32.3708260704 -26 26 20.601330540 15.23 14.364 13.061   11.489 ~ 20 0
7 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1817 0
8 NGC 6121 370 RG* 16 23 38.8582043016 -26 25 42.784867632 15.26 14.362 13.071   11.528 ~ 23 0
9 Cl* NGC 6121 ALC 318 RG* 16 23 43.0923509424 -26 28 07.468793256 15.50 14.75 13.548   12.047 ~ 17 0
10 NGC 6121 78 RG* 16 23 47.8825228152 -26 29 48.285234744 15.50 14.783 13.575   12.106 ~ 23 0
11 2MASS J18593517+3926488 RG* 18 59 35.1714683304 +39 26 48.896419380           ~ 24 0
12 TYC 3124-2345-1 RG* 19 01 13.9637622744 +41 09 06.025364748   12.13 11.73     ~ 28 0
13 2MASS J19025811+4251431 RG* 19 02 58.1123511168 +42 51 43.186448988           ~ 25 0
14 2MASS J19071107+4231237 RG* 19 07 11.0718029400 +42 31 23.776450464           ~ 18 0
15 2MASS J19074933+4849248 RG* 19 07 49.3492906320 +48 49 24.931900668           ~ 18 0
16 TYC 3132-1803-1 RG* 19 08 41.6304756240 +43 52 10.322923008   11.91 11.14     ~ 26 0
17 TYC 3129-1563-1 RG* 19 16 07.6456941936 +42 46 32.004554412   13.40 12.20     F8IV 25 0
18 NGC 6791 OpC 19 20 53.0 +37 46 41   10.52 9.5     ~ 1018 0
19 TYC 3564-1597-1 RG* 19 36 52.2054153288 +49 35 59.382765708   12.25 11.34     ~ 27 0
20 TYC 3564-630-1 RG* 19 37 12.0103216392 +50 24 55.585764540   11.27 10.44     G0 24 0
21 NGC 6819 OpC 19 41 18.5 +40 11 24   8.21 7.3     ~ 604 0
22 TYC 5809-1204-1 PM* 22 15 16.2001998576 -13 50 06.720591840   12.748 11.857     ~ 6 0
23 TYC 5239-444-1 Pe* 22 35 01.2796831224 -05 54 34.933658040   12.81 12.24     ~ 5 0
24 UCAC4 376-178492 Pe* 22 39 57.8206560792 -14 53 20.264811612   13.555 12.717 12.689   ~ 8 0

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2023.09.27-18:02:53

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