J/A+A/674/A157 Li-rich giant stars in open clusters (Tsantaki+, 2023)
Search for lithium-rich giants in 32 open clusters with high-resolution
spectroscopy.
Tsantaki M., Delgado-Mena E., Bossini D., Sousa S.G., Pancino E.,
Martins J.H.C.
<Astron. Astrophys. 674, A157 (2023)>
=2023A&A...674A.157T 2023A&A...674A.157T (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, giant ; Abundances ; Stars, masses ;
Effective temperatures
Keywords: techniques: spectroscopic - stars: abundances - stars: evolution -
planetary systems - stars: rotation
Abstract:
Lithium-rich giant stars are rare and their existence challenges our
understanding of stellar structure and evolution. We profit from the
high-quality sample gathered to search for planets in open clusters
with HARPS and UVES, in order to search for Li-rich giants and to
identify the Li enrichment mechanisms responsible. We derive stellar
parameters for 247 stars belonging to 32 open clusters, with
0.07Ga<ages<3.6Ga. We employed the spectral synthesis technique code
FASMA for the abundance analysis of 228 stars from our sample. We also
determined ages, distances, and extinction using astrometry and
photometry from Gaia and PARSEC isochrones to constrain their
evolutionary stage. We have found 14 canonical Li-rich giant stars
which have experienced the first dredge-up. This corresponds to 6% of
our total sample, which is higher than what is typically found for
field stars. The majority of the stars (11/14) are located at the red
clump, two lie on the red giant branch, and for one we could not
conclude on its evolutionary stage. Apart from the canonical limit, we
use the maximum Li abundance of the progenitor stars as a criterion
for Li enrichment and find 12 Li enriched stars (5/12 appear in the
red clump, 5/12 at the upper red giant branch and two we could not
conclude on its evolutionary stage). We find Li enhancement also among
eight stars which have passed the first dredge up and show strong Li
lines based on the fact that stars at the same evolutionary stage in
the same cluster have significantly different Li abundances. Our
Li-rich giants are found in various evolutionary stages implying that
no unique Li production mechanism is responsible for Li enrichment but
rather different intrinsic or external mechanisms can be
simultaneously at play.
Description:
Stellar characterization of giant stars in open clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 80 260 Coordinates, V and G magnitudes, and Gaia ID
tablea2.dat 80 260 Parameters derived in this work from our
spectroscopic analysis
tablea3.dat 64 260 Parameters calculated with methods other than
spectroscopy
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Star Unique star ID
16- 17 I2 h RAh Right ascension (J2000)
19- 20 I2 min RAm Right ascension (J2000)
22- 27 F6.3 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 42 F7.4 arcsec DEs Declination (J2000)
44- 49 F6.3 mag Vmag ? V magnitude
51- 56 F6.3 mag Gmag ? Gaia G magnitude
58- 76 I19 --- GaiaDR2 ? Gaia DR2 source ID
78- 80 A3 --- Notes Notes (1)
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Note (1): Notes as follows:
B = Binary
NM = Non Member
PL = Planet host
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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- 13 A13 --- Star Unique star ID
15- 20 F6.1 K Teff Effective temperature
22- 25 F4.1 K e_Teff Error in Effective temperature
27- 30 F4.2 [cm/s2] logg Surface gravity
32- 35 F4.2 [cm/s2] e_logg Error in surface gravity
37- 41 F5.2 [-] [Fe/H] Metallicity
43- 46 F4.2 [-] e_[Fe/H] Error in metallicity
48- 50 I3 --- snr Signal-to-noise ratio
52- 56 F5.2 Msun Mass ? Mass
58- 61 F4.2 Msun e_Mass ? Error in Mass
63- 67 F5.2 [-] Li ? Li abundance
69- 74 F6.2 [-] e_Li ? Error in Li abundance
76- 80 F5.2 [-] LiNLTE ? Li abundance in NLTE
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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- 13 A13 --- Star Unique star ID
15- 20 F6.1 K TeffPhot ? Effective temperature (photometry)
22- 25 F4.1 K e_TeffPhot ? Error in Effective temperature
(photometry)
27- 30 F4.2 [cm/s2] loggTrig ? Surface gravity (spectro-photometry)
32- 35 F4.2 [cm/s2] e_loggTrig ? Error in surface gravity
(spectro-photometry)
37- 40 F4.2 Msun MassPhot ? Mass (spectro-photometry)
42- 45 F4.2 Msun e_MassPhot ? Error in Mass (spectro-photometry)
47- 51 F5.2 [-] LiPhot ? Li abundance (spectro-photometry)
53- 58 F6.2 [-] e_LiPhot ? Error in Li abundance
(spectro-photometry)
60- 64 F5.2 [-] LiNLTEPhot ? Li abundance in NLTE
(spectro-photometry)
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Acknowledgements:
Maria Tsantaki, maria.tsantaki(at)inaf.it
(End) Patricia Vannier [CDS] 02-Jun-2023