J/ApJ/877/104 High-res. spectroscopy of LAMOST Li-rich giants (Zhou+, 2019)
High-resolution spectroscopic analysis of a large sample of Li-rich giants found
by LAMOST.
Zhou Y., Yan H., Shi J., Blanco-Cuaresma S., Gao Qi, Pan K., Xu X.,
Zhang J., Zhao G.
<Astrophys. J., 877, 104 (2019)>
=2019ApJ...877..104Z 2019ApJ...877..104Z
ADC_Keywords: Stars, giant; Abundances; Spectra, optical; Rotational velocities;
Effective temperatures; Stars, masses; Stars, ages
Keywords: stars: abundances ; stars: chemically peculiar ; stars: evolution ;
stars: late-type
Abstract:
The discovery of Li-rich giants has introduced a new challenge for
standard stellar evolution models. To resolve this issue, the number
of this type of object has been rapidly increased through the
development of worldwide surveys. Taking advantage of the Large Sky
Area Multi-Object Fiber Spectroscopic Telescope survey, 44 new Li-rich
giants are reported, which are confirmed with high-resolution
observations. Based on the high-resolution and high signal-to-noise
spectra, we derived the atmospheric parameters and elemental
abundances with the spectral synthesis method. We performed a detailed
analysis of their evolutionary stages, infrared excess, projected
rotational velocity (vsini), and stellar population. We find that
(1) the Li-rich giants concentrate at the evolutionary status of the
red giant branch bump, red clump, and asymptotic giant branch;
(2) three of them are fast rotators and none exhibit infrared excess.
Our results imply that the origins of Li enrichment are most likely to
be associated with the extra mixing in the stellar interior, and the
external sources might only make a minor contribution. Moreover,
various Li-rich episodes take place at different evolutionary stages.
Description:
The Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST)
is able to take a maximum of 4000 spectra in a single exposure with a
limiting magnitude of r=18.5 and a resolution power (R) of ∼1800. The
wavelength range is ∼3700-9000Å, which covers the Li resonance line
at 6708Å.
We implemented the follow-up observations with five telescopes, they
are 1.8m and 2.4m telescopes at the Lijiang Observatory with R∼30000,
3.5m telescope at Apache Point Observatory with R∼31500, 2.4m APF
telescope located at the Mt. Hamilton station of UCO/Lick Observatory
(R∼80000), and 8m Subaru telescope with R∼40000. The mean
signal-to-noise ratio (S/N) of the spectra is 80. The details of
observation are listed in Table 1.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 90 45 Observation information
table2.dat 201 44 Additional information of the Li-rich giants
--------------------------------------------------------------------------------
See also:
II/328 : AllWISE Data Release (Cutri+ 2013)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/475/1003 : Stellar parameters of G and K giant stars (Hekker+, 2007)
J/AJ/137/4282 : Red giant stars in clusters. II. M13 & M92 (Meszaros+, 2009)
J/A+A/503/545 : EWs of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)
J/A+A/545/A32 : Chemical abundances of 1111 FGK stars (Adibekyan+, 2012)
J/ApJ/757/109 : Rotational vel. + Li abundance in K giants (Carlberg+, 2012)
J/AJ/144/135 : Spitzer 24µm phot. of Hipparcos F stars (Mizusawa+, 2012)
J/AJ/150/123 : Catalog of 316 K giant candidates (Rebull+, 2015)
J/ApJ/819/135 : Lithium-rich giants in globular clusters (Kirby+, 2016)
J/A+A/613/A47 : Radial velocities of 12 evolved stars (Adamow+, 2018)
J/A+A/610/A38 : Li enrichment histories of the thick/thin disc (Fu+, 2018)
J/ApJ/858/L7 : Red clump stars selected from LAMOST & APOGEE (Ting+, 2018)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1-19 A19 --- LAMOST LAMOST identifier (JHHMMSS.ss+DDMMSS.s)
21-22 I2 h RAh Hour of right ascension (J2000)
24-25 I2 min RAm Minute of right ascension (J2000)
27-31 F5.2 s RAs Second of right ascension (J2000)
33 A1 --- DE- Sign of declination (J2000)
34-35 I2 deg DEd Degree of declination (J2000)
37-38 I2 arcmin DEm Arcminute of declination (J2000)
40-44 F5.2 arcsec DEs Arcsecond of declination (J2000)
46-51 F6.3 mag Vmag [9.22/12.35] V magnitude
53-62 A10 --- Nexp Number of exposure x exposure time
64-75 A12 --- Tel Telescope
77-87 A11 "Y:M:D" Date Date of observation (UT)
88 A1 --- --- [/]
89-90 I2 d Day2 ? Second day of observation
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- LAMOST LAMOST identifier (JHHMMSS.ss+DDMMSS.s)
21- 30 F10.6 deg RAdeg [14.45/357.7] Right Ascension (J2000)
32- 40 F9.6 deg DEdeg [-4.82/86.9] Declination (J2000)
42- 45 I4 K Teff [3780/5188] Effective temperature
47- 49 I3 K e_Teff [11/134] Error in Teff
51- 54 F4.2 [cm/s2] logg [0.62/3.33] Log of the surface gravity
56- 59 F4.2 [cm/s2] e_logg [0.1/0.81] Error in logg
61- 65 F5.2 --- [Fe/H] [-0.79/0.26] Metallicity
67- 70 F4.2 --- e_[Fe/H] [0.02/0.2] Error in Metallicity
72- 75 F4.2 km/s Vt [0.92/2.12] Microturbulence velocity
77- 80 F4.2 km/s e_Vt [0.03/0.28] Error in Vt
82- 85 F4.2 --- A(Li)LTE [1.63/4.08] LTE Li abundance
87- 90 F4.2 --- e_A(Li)LTE [0.03/0.22] Error in A(Li)LTE
92- 95 F4.2 --- A(Li)NLTE [1.65/4.18] NLTE Li abundance
97-100 F4.1 km/s vsini [0.5/13.7] Projected rotational velocity
102-104 F3.1 km/s e_vsini [0.2/2.0] Error in vsini
106-111 F6.2 km/s RV [-93.62/59.21] Radial velocity
113-116 F4.2 km/s e_RV [0.22/1.18] Error in RV
118-121 I4 K Teffph [3652/5119] Photometric effective
temperature
123-127 F5.3 [cm/s2] loggph [0.73/2.95] Photometric surface gravity
129-135 F7.3 km/s U [-79.15/62.84] U Galactic velocity
137-143 F7.3 km/s V [-71.99/39.74] V Galactic velocity
145-151 F7.3 km/s W [-41.35/46.64] W Galactic velocity
153-158 F6.3 --- Pthin [16.3/99.3] Thin disk membership probability
160-165 F6.3 --- Pthick [0.7/83] Thick disk Membership probability
167-172 F6.3 Gyr Age [1.14/11.43] Stellar age
174-178 F5.3 Msun Mass [0.87/2.08] Stellar mass
180-184 F5.3 [Lsun] logLum [1.47/2.89] Log luminosity
186-190 F5.3 [Lsun] e_logLum [0.067/0.131] Error in logLum
192-195 F4.1 --- Chi2 [-1.7/1.3] chi-square of band 1 and band4
of WISE (1)
197-199 A3 --- Phase Stellar evolutionary phase (2)
201-201 A1 --- f_Phase Flag on Phase (3)
--------------------------------------------------------------------------------
Note (1): Chi2>3.0 is a criterion regarded as a significant small IR excess.
Note (2): The Roman numerals from I to V indicate the stages of before RGB
bump, the RGB bump, above RGB bump, RC and AGB.
Note (3): For the RC stars, flag as follows:
a = the star was consistently classified by the two approaches of the
HR-diagram and the data-driven.
b = the star was defined alone by the position of HR-diagram without
asteroseismic data.
c = the star was identified by means of asteroseismic parameters
from the RC catalog of Ting+ 2018, J/ApJ/858/L7
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-Nov-2020