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

M. Valentini; C. Chiappini; D. Bossini; A. Miglio; G. R. Davies; B. Mosser; Y. P. Elsworth; S. Mathur; R. A. García; L. Girardi; T. S. Rodrigues; M. Steinmetz; A. Vallenari

doi:10.1051/0004-6361/201834081

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

M. Valentini, C. Chiappini, D. Bossini, A. Miglio, G. R. Davies, B. Mosser, Y. P. Elsworth, S. Mathur, R. A. García, L. Girardi, T. S. Rodrigues, M. Steinmetz, A. Vallenari

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

8 Citations (Scopus)

196 Downloads (Pure)

Abstract

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 0.80−1.0 M_⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr 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 −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).

Original language	English
Article number	A173
Number of pages	23
Journal	Astronomy and Astrophysics
Volume	627
DOIs	https://doi.org/10.1051/0004-6361/201834081
Publication status	Published - 18 Jul 2019

Bibliographical note

21 pages, 19 figures. Accepted

Keywords

Asteroseismology
Stars: abundances
Stars: fundamental parameters

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1051/0004-6361/201834081Licence: None: All rights reserved

Valentini_et_al_Masses_and_ages_for_metal-poor_stars_A&A_2019
Valentini et al., Masses and ages for metal-poor stars: a pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars, A&A 627, A173 (2019) https://doi.org/10.1051/0004-6361/201834081 Reproduced with permission from Astronomy & Astrophysics, © ESO.
Final published version, 1.29 MBLicence: Other (please specify with Rights Statement)

Cite this

Valentini, M., Chiappini, C., Bossini, D., Miglio, A., Davies, G. R., Mosser, B., Elsworth, Y. P., Mathur, S., García, R. A., Girardi, L., Rodrigues, T. S., Steinmetz, M., & Vallenari, A. (2019). Masses and ages for metal-poor stars: a pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars. Astronomy and Astrophysics, 627, Article A173. https://doi.org/10.1051/0004-6361/201834081

@article{1d9403bd143a446e813fbc77732d211a,

title = "Masses and ages for metal-poor stars: a pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars",

abstract = "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 0.80−1.0 M⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr 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 −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).",

keywords = "Asteroseismology, Stars: abundances, Stars: fundamental parameters",

author = "M. Valentini and C. Chiappini and D. Bossini and A. Miglio and Davies, {G. R.} and B. Mosser and Elsworth, {Y. P.} and S. Mathur and Garc{\'i}a, {R. A.} and L. Girardi and Rodrigues, {T. S.} and M. Steinmetz and A. Vallenari",

note = "21 pages, 19 figures. Accepted",

year = "2019",

month = jul,

day = "18",

doi = "10.1051/0004-6361/201834081",

language = "English",

volume = "627",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Valentini, M, Chiappini, C, Bossini, D, Miglio, A, Davies, GR, Mosser, B, Elsworth, YP, Mathur, S, García, RA, Girardi, L, Rodrigues, TS, Steinmetz, M & Vallenari, A 2019, 'Masses and ages for metal-poor stars: a pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars', Astronomy and Astrophysics, vol. 627, A173. https://doi.org/10.1051/0004-6361/201834081

TY - JOUR

T1 - Masses and ages for metal-poor stars

T2 - a pilot programme combining asteroseismology and high-resolution spectroscopic follow-up of RAVE halo stars

AU - Valentini, M.

AU - Chiappini, C.

AU - Bossini, D.

AU - Miglio, A.

AU - Davies, G. R.

AU - Mosser, B.

AU - Elsworth, Y. P.

AU - Mathur, S.

AU - García, R. A.

AU - Girardi, L.

AU - Rodrigues, T. S.

AU - Steinmetz, M.

AU - Vallenari, A.

N1 - 21 pages, 19 figures. Accepted

PY - 2019/7/18

Y1 - 2019/7/18

N2 - 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 0.80−1.0 M⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr 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 −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).

AB - 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 0.80−1.0 M⊙ range. The inferred model-dependent stellar ages are found to range from 7.4 Gyr to 13.0 Gyr 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 −2 dex) are very old >9 Gyr (14 out of 19 stars), and all of the stars are older than >5 Gyr (within the 68 percentile confidence level).

KW - Asteroseismology

KW - Stars: abundances

KW - Stars: fundamental parameters

UR - http://www.scopus.com/inward/record.url?scp=85070071978&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201834081

DO - 10.1051/0004-6361/201834081

M3 - Article

SN - 0004-6361

VL - 627

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A173

ER -

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

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

Fingerprint

Cite this