J/A+A/594/A120 Gaia-ESO Survey: Hydrogen lines in red giants (Bergemann+, 2016)
The Gaia-ESO Survey: Hydrogen lines in red giants directly trace stellar mass.
Bergemann M., Serenelli A., Schonrich R., Ruchti G., Korn A., Hekker S.,
Kovalev M., Mashonkina L., Gilmore G., Randich S., Asplund M., Rix H.-W.,
Casey A.R., Jofre P., Pancino E., Recio-Blanco A., De Laverny P.,
Smiljanic R., Tautvaisiene G., Bayo A., Lewis J., Koposov S., Hourihane A.,
Worley C., Morbidelli L., Franciosini E., Sacco G., Magrini L., Damiani F.,
Bestenlehner J.M.
<Astron. Astrophys., 594, A120 (2016)>
=2016A&A...594A.120B 2016A&A...594A.120B (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, giant ; Photometry, H-alpha
Keywords: techniques: spectroscopic - stars: fundamental parameters -
stars: late-type - Galaxy: stellar content
Abstract:
Red giant stars are perhaps the most important type of stars for
Galactic and extra-galactic archaeology: they are luminous, occur in
all stellar populations, and their surface temperatures allow precise
abundance determinations for many different chemical elements. Yet,
the full star formation and enrichment history of a galaxy can be
traced directly only if two key observables can be determined for
large stellar samples: age and chemical composition. While
spectroscopy is a powerful method to analyse the detailed abundances
of stars, stellar ages are the missing link in the chain, since they
are not a direct observable. However, spectroscopy should be able to
estimate stellar masses, which for red giants directly infer ages
provided their chemical composition is known. Here we establish a new
empirical relation between the shape of the hydrogen line in the
observed spectra of red giants and stellar mass determined from
asteroseismology. The relation allows determining stellar masses and
ages with an accuracy of 10-15%. The method can be used with
confidence for stars in the following range of stellar parameters:
4000<Teff<5000K, 0.5<logg<3.5, -2.0<[Fe/H]<0.3, and luminosities
logL/L☉<2.5. Our analysis provides observational evidence that
the Hα spectral characteristics of red giant stars are tightly
correlated with their mass and therefore their age. We also show that
the method samples well all stellar populations with ages above 1Gyr.
Targeting bright giants, the method allows obtaining simultaneous age
and chemical abundance information far deeper than would be possible
with asteroseismology, extending the possible survey volume to remote
regions of the Milky Way and even to neighbouring galaxies such as
Andromeda or the Magellanic Clouds even with current instrumentation,
such as the VLT and Keck facilities.
Description:
Our main dataset contains the high-resolution stellar spectra from the
Gaia-ESO second and third data releases (iDR2, iDR3). The
high-resolution Gaia-ESO spectra are obtained with UVES spectrograph
at the VLT, R∼47000. The data are publicly available through the ESO
archive. The majority of the spectra have S/Ns between 50 and 220. In
the top tier we have the stars with high-quality asteroseismic data
from CoRoT, but we also include red giants observed in open and
globular clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 59 21 Observational data for the Gaia-ESO stars
tablea2.dat 92 21 Stellar parameters and Halpha measurements for
the Gaia-ESO field stars
tablea3.dat 59 72 Observational data for the Gaia-ESO stars in
clusters
tablea4.dat 65 72 Stellar parameters and Halpha measurements for
the Gaia-ESO cluster stars
tablea5.dat 74 48 Stellar parameters and Halpha measurements for
the Kepler stars from Thygesen et al. (2012,
Cat. J/A+A/543/A160)
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See also:
J/A+A/543/A160 : Normalized spectra of 82 Kepler red giants (Thygesen+, 2012)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- CoRoT CoRoT ID
11- 26 A16 --- GES Gaia-ESO ID, HHMMSSss+DDMMSSs
28- 30 I3 --- S/N Signal-to-noise ratio
32- 43 F12.7 deg RAdeg Right ascension (J2000)
45- 54 F10.7 deg DEdeg Declination (J2000)
56- 59 I4 km/s RV Radial velocity
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- CoRoT CoRoT ID
11- 26 A16 --- GES Gaia-ESO ID, HHMMSSss+DDMMSSs
28- 31 F4.2 0.1nm WHalpha Halpha equivalent width
33- 36 F4.2 0.1nm f0 Line depth parameter
38- 42 F5.2 Gyr Age Age
44- 47 F4.2 Gyr e_Age rms uncertainty on Age
49- 52 F4.2 Msun Mass Mass
54- 57 F4.2 Msun e_Mass rms uncertainty on Mass
59- 62 I4 K Teff Effective temperature
64- 66 I3 K e_Teff rms uncertainty on Teff
68- 71 F4.2 [cm/s2] logg Surface gravity (1)
73- 76 F4.2 [cm/s2] e_logg rms uncertainty on logg
78- 82 F5.2 [-] [Fe/H] Metallicity
84- 87 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H]
89- 92 F4.2 [Lsun] logL Luminosity
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Note (1): Surface gravities are determined using the asteroseismic data.
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster name
10- 25 A16 --- GES Gaia-ESO ID, HHMMSSss+DDMMSSs
27- 29 I3 --- S/N Signal-to-noise ratio
32- 42 F11.7 deg RAdeg Right ascension (J2000)
44- 54 F11.7 deg DEdeg Declination (J2000)
56- 59 I4 km/s RV Radial velocity
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster name
10- 25 A16 --- GES Gaia-ESO ID, HHMMSSss+DDMMSSs
27- 30 F4.2 0.1nm WHalpha Halpha equivalent width
32- 35 F4.2 0.1nm f0 Line depth parameter
37- 40 I4 K Teff Effective temperature
42- 44 I3 K e_Teff rms uncertainty on Teff
46- 49 F4.2 [cm/s2] logg Surface gravity
51- 54 F4.2 [cm/s2] e_logg rms uncertainty on logg
56- 60 F5.2 [-] [Fe/H] Metallicity
62- 65 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H]
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC Kepler ID
9 A1 --- n_KIC [*] Note on KIC (1)
11- 14 F4.2 0.1nm WHalpha Halpha equivalent width
16- 19 F4.2 0.1nm f0 Line depth parameter
21- 25 F5.2 Gyr Age ?=- Age
27- 30 F4.2 Gyr e_Age ?=- rms uncertainty on Age
32- 35 F4.2 Msun Mass Mass
37- 40 F4.2 Msun e_Mass rms uncertainty on Mass
42- 45 I4 K Teff Effective temperature
47- 49 I3 K e_Teff rms uncertainty on Teff
51- 54 F4.2 [cm/s2] logg Surface gravity (2)
56- 60 F5.2 [-] [Fe/H] Metallicity
62- 65 F4.2 [-] e_[Fe/H] rms uncertainty on [Fe/H]
67- 70 F4.2 [Lsun] logL ?=- Luminosity
72- 74 A3 --- Type Type (RGB or RC)
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Note (1): The stars marked with a star symbol are targets of
Silva Aguirre et al. (in prep.).
Note (2): Surface gravities are determined using the asteroseismic data.
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History:
17-Feb-2017: From electronic version of the journal
01-Mar-2024: positions for NGC 4372 sources corrected
(End) Patricia Vannier [CDS] 20-Jan-2017