J/ApJ/944/L5 Lithium abundances in Kepler giants (Mallick+, 2023)
Lithium abundances in giants as a function of stellar mass: evidence for He
flash as the source of Li enhancement in low-mass giants.
Mallick A., Singh R., Reddy B.E.
<Astrophys. J., 944, L5 (2023)>
=2023ApJ...944L...5M 2023ApJ...944L...5M
ADC_Keywords: Abundances; Stars, giant; Asteroseismology; Spectra, optical
Keywords: Stellar abundances ; Red giant clump ; Helium burning ;
Asteroseismology
Abstract:
In this work, we studied the distribution of lithium abundances in
giants as a function of stellar mass. We used a sample of 1240 giants
common among Kepler photometric and LAMOST medium-resolution (R∼7500)
spectroscopic survey fields. The asteroseismic ΔP-Δν
diagram is used to define core He-burning red clump giants and red
giant branch stars with an inert He core. Li abundances have been
derived using spectral synthesis for all sample stars. Directly
measured values of asteroseismic parameters ΔP (or ΔΠ1)
and Δν are either taken from the literature or measured in
this study. Of the 777 identified red clump giants, we found 668
low-mass (≤2M☉) primary red clump giants and 109 high-mass
(>2M☉) secondary red clump giants. Observed Li abundances in
secondary red clump giants agree with the theoretical model
predictions. The lack of Li-rich giants among secondary red clump
giants and the presence of Li-rich, including super Li-rich, giants
among primary red clump stars reinforces the idea that helium flash
holds the key for Li enrichment among low-mass giants. The results
will further constrain theoretical models searching for a physical
mechanism for Li enhancement among low-mass red clump giants. Results
also serve as observational evidence that only giants with mass less
than ∼2M☉ develop a degenerate He core and undergo He flash.
Description:
We adopted a sample of 16094 giants from the catalog by
Yu+ (2018, J/ApJS/236/42), who compiled giants for which oscillations
were detected. We cross-matched the Yu+ (2018) sample with the LAMOST
medium-resolution spectroscopic survey DR7 catalog (Luo+ 2022, V/156).
We found 1240 giants common between the two catalogs. All the giants
have reasonably good spectra with signal-to-noise ratio (S/N)≥30.
See further explanations in Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 1240 Derived and adopted parameters of sample giants
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
J/A+A/503/541 : Neutral Li in late-type stars non-LTE calcul. (Lind+, 2009)
J/ApJ/757/109 : Rot. velocities + Li abundance in K giants (Carlberg+, 2012)
J/A+A/540/A143 : Oscillations of red giants with Kepler (Mosser+, 2012)
J/ApJ/765/L41 : Asteroseismic classification of KIC objects (Stello+, 2013)
J/MNRAS/448/822 : LAMOST candidate members of star clusters (Xiang+, 2015)
J/AJ/151/144 : ASPCAP weights for APOGEE chemical elements (Garcia+, 2016)
J/A+A/588/A87 : Seismic global parameters of 6111 KIC (Vrard+, 2016)
J/ApJS/236/42 : Asteroseismology of ∼16000 Kepler red giants (Yu+, 2018)
J/MNRAS/484/2000 : Study of Lithium-rich giants with GALAH (Deepak+, 2019)
J/ApJ/914/116 : Lithium abundances from LAMOST MRS. I. (Gao+, 2021)
J/MNRAS/505/5340 : Lithium-rich stars in the GALAH survey DR3 (Martell+, 2021)
J/ApJ/940/12 : HeIλ10830 in red giant stars with HPF (Sneden+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC [4136835/11707798] Kepler Input Catalog
identifier
10- 13 I4 K Teff [4168/5451] Effective temperature (1)
15- 17 I3 K e_Teff [75/181] Uncertainty in Teff
19- 23 F5.3 [cm/s2] logg [1.59/3.4] log surface gravity (1)
25- 29 F5.3 [cm/s2] e_logg [0.006/0.2] Uncertainty in logg
31- 35 F5.2 [Sun] [Fe/H] [-2.44/0.57] Metallicity (1)
37- 40 F4.2 [Sun] e_[Fe/H] [0.1/0.3] Uncertainty in [Fe/H]
42- 46 F5.3 km/s VTurb [1.14/1.9] Microturbulent velocity (1)
48- 52 F5.3 km/s e_VTurb [0/0.03] Uncertainty in VTurb
54- 57 F4.2 Msun Mass [0.6/4.9] Mass
59- 62 F4.2 Msun e_Mass [0.04/1.6] Uncertainty in Mass
64- 67 F4.2 [-] A(Li) [0.27/3.9] LTE derived Li abundance
69- 72 F4.2 [-] e_A(Li) [0.06/0.3] Uncertainty in A(Li)
74- 78 F5.2 [-] Delta [-0.37/0.33]? The NLTE correction to A(Li)
80- 85 F6.3 uHz Deltanu [1/18.7] THe asteroseismic Δν value
87- 91 F5.3 uHz e_Deltanu [0.009/1.3] Uncertainty in Deltanu
93- 98 F6.2 s DeltaP [9.99/357.1] The asteroseismic ΔP value
100-104 F5.2 s e_DeltaP [0.16/79.5] Uncertainty in DeltaP
106 I1 --- f_DeltaP [1/2] Flag on DeltaP (2)
108 I1 --- Status [0/2]? Evolutionary status code (3)
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Note (1): The stellar parameters Teff, log(g) and [Fe/H] are adapted from
the Yu+ 2018, J/ApJS/236/42 catalog. See section 3.2
for a discussion on how Vturb is derived.
Note (2): Flag as follows:
1 = from this work (656 occurrences)
2 = actually ΔΠ1 from Vrard+ 2016, J/A+A/588/A87
Note (3): Code as follows:
0 = RGB (red giant branch; 463 occurrences)
1 = pRC (low-mass (≤2M☉ red clump (RC) giants or the
primary RC giants; 668 occurrences)
2 = sRC (high-mass (>2M☉) RC giants or secondary RC giants;
109 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 31-Jan-2025