J/A+A/706/A133 Halo and thick-disc giants Li and rotation (de la Reza+, 2026)
Lithium abundance and stellar rotation in the Galactic halo and thick disc.
de la Reza R., Llorente de Andres F., Alfaro E.J., Chavero C.
<Astron. Astrophys. 706, A133 (2026)>
=2026A&A...706A.133D 2026A&A...706A.133D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, population II ; Stars, halo ; Abundances ;
Rotational velocities
Keywords: stars: abundances - stars: evolution - stars: Population II -
Galaxy: halo
Abstract:
The stellar evolution of lithium-rich (Li-rich) giant stars at very
low metallicities remains largely unexplored to date. Using mainly two
recent large LAMOST catalogues of field, low-mass giant stars (both
Li-rich and Li-poor) with metallicities ranging from -4.0 up to -1.0,
we studied some of the conditions for Li enrichment and the general
distribution of stellar rotations in the Galactic halo and thick disc.
Due to the scarcity of stars with [Fe/H]←3.0, only three Li-rich
red giant branch (RGB) stars are known in this regime. The full
observational appearance of all giants, across the horizontal branch
(HB) and asymptotic giant branch (AGB) advanced stages of evolution
(with Li abundances up to 6.15dex) have been detected for
metallicities > -2.5.
Among these stars, we detected the presence of IR excesses that are
considered to be indicative of giant stars losing mass, showing a
recent episodic Li-enrichment process related to the Cameron-Fowler
mechanism for the formation of new 7Li. Because stars presenting IR
excesses are distributed across the majority of metallicity values, we
suggest this mechanism is at work throughout an important part of the
evolutionary history of the Galaxy. Based on these IR excesses, we
identified three Li thresholds: ∼1.5dex for RGB stars, ∼0.5dex for
HB stars, and ~-0.5dex for AGB stars, thereby establishing a new
criterion to characterise Li-rich giants in the halo and thick disc.
We carried out a first extensive study of stellar rotations in
metal-poor giant stars, revealing the following results: (a) a plateau
appears for velocities greater than 40km/s extending up to near
90km/s, with Li abundances ranging from 1.02 to 1.82dex; (b) among
Li-rich giant stars with vsini>40km/s, a clear trend toward increasing
rotation is observed up to near 90 km/s as metallicities decrease from
-1.0 to -2.5; (c) the presence of RGB and HB Li-rich giant stars with
rotations up to 90 km/s suggests that internal stellar models must
account for extended ^3He reservoir lifetimes as a source of 7Li
considering these velocities. The velocity around 40km/s appears to be
a new critical value that merits further investigation.
Description:
This catalogue contains data for low-mass field giant stars belonging
to the Galactic halo and thick disc, aimed at studying lithium
enrichment and stellar rotation at low metallicity.
The sample is mainly based on the LAMOST DR9 catalogue for stellar
parameters and lithium abundances, combined with projected rotational
velocities from the LAMA LAMOST catalogue, astrometry from Gaia DR3,
distances from Bailer-Jones et al. (2021AJ....161..147B 2021AJ....161..147B, Cat. I/352),
and infrared photometry from WISE.
Only stars with metallicities in the range -4.0≤[Fe/H]≤-1.0 and with
giant-star atmospheric parameters were selected. The evolutionary
stage (RGB, HB, or AGB) was assigned based on surface gravity.
Table 2 lists 1703 Li-rich giant stars, providing their identifiers,
positions, atmospheric parameters, metallicities, lithium abundances,
alpha-element enhancement, infrared excess indicators (W1-W4),
Galactocentric positions, and velocity components.
Table 4 provides the subset of stars for which projected rotational
velocities (vsini) are available, together with the corresponding
stellar parameters and lithium abundances, allowing the analysis of
the relation between rotation and lithium enrichment.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 117 1703 Li-rich giant stars list
table4.dat 159 3564 Subset of stars for which projected rotational
velocities (vsini) are available
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See also:
I/352 : Distances to 1.47 billion stars in Gaia EDR3
(Bailer-Jones+, 2021)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
J/ApJS/271/58 : Lithium abundances from LAMOST MRS DR9 spectra (Ding+, 2024)
J/ApJS/238/16 : LAMOST-DR3 very metal-poor star catalog (Li+, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 44 I4 K Teff Effective temperature
46- 49 F4.2 [cm/s2] logg Surface gravity
51- 55 F5.2 [Sun] [Fe/H] Metallicity [Fe/H]
57- 59 F3.1 [-] A(Li) Lithium abundance A(Li)
61- 65 F5.2 [-] [alpha/Fe] ? alpha-element enhancement [alpha/Fe]
67- 71 F5.2 mag W1-W4 WISE colour W1-W4
73- 76 F4.2 mag e_W1-W4 ? Error of WISE colour W1-W4
78- 82 I5 pc XGC Galactocentric X coordinate
84- 89 I6 pc YGC Galactocentric Y coordinate
91- 96 I6 pc ZGC Galactocentric Z coordinate
98-103 F6.1 km/s Vomega ? Radial velocity
(Galactocentric cylindrical)
105-110 F6.1 km/s Vphi ? Rotational velocity
(Galactocentric cylindrical)
112-117 F6.1 km/s VZ ? Vertical velocity
(Galactocentric cylindrical)
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier
22- 33 F12.8 deg RAdeg Right Ascension (J2000)
35- 46 F12.8 deg DEdeg Declination (J2000)
49- 55 F7.2 K Teff Effective temperature
59- 63 F5.3 [cm/s2] logg Surface gravity
66- 71 F6.3 [Sun] [Fe/H] Metallicity [Fe/H]
74- 79 F6.3 [-] A(Li) Lithium abundance A(Li)
81- 87 F7.3 km/s vsini ? Projected rotational velocity
90- 95 F6.3 km/s e_vsini ? Error of projected rotational velocity
98-107 F10.3 pc XGC Galactocentric X coordinate
109-118 F10.3 pc YGC Galactocentric Y coordinate
120-129 F10.3 pc ZGC Galactocentric Z coordinate
132-139 F8.3 km/s Vomega ? Radial velocity
(Galactocentric cylindrical)
142-149 F8.3 km/s Vphi ? Rotational velocity
(Galactocentric cylindrical)
152-159 F8.3 km/s VZ ? Vertical velocity
(Galactocentric cylindrical)
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Acknowledgements:
Ramiro de la Reza, carochavero(at)gmail.com
(End) Patricia Vannier [CDS] 02-Jan-2026