J/A+A/698/A7 Pleiades LAMOST mid-resolution observations (Frasca+, 2025)
LAMOST medium-resolution observations of the Pleiades.
Frasca A., Zhang J.Y., Alonso-Santiago J., Fu J.N., Molenda-Zakowicz J.,
Catanzaro G., De Cat P.
<Astron. Astrophys. 698, A7 (2025)>
=2025A&A...698A...7F 2025A&A...698A...7F (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Abundances ; Effective temperatures ;
Radial velocities ; Rotational velocities; Balmer lines
Keywords: stars: abundances - stars: activity - binaries: spectroscopic -
stars: flare - stars: fundamental parameters -
open clusters and associations: individual: Pleiades
Abstract:
In this work, we present the results of our analysis of
medium-resolution LAMOST spectra of late-type candidate members of
the Pleiades with the aim of determining the stellar parameters,
activity level, and lithium abundance.
We used the ROTFIT code to determine the atmospheric parameters (Teff,
logg, and [Fe/H]), along with the radial velocity (RV) and
projected rotation velocity (vsini). Moreover, for late-type stars
(Teff≤6500K), we also calculated the Hα and LiI 6708 net
equivalent width by means of the subtraction of inactive photospheric
templates. We also used the rotation periods from the literature and
we purposely determined them for 89 stars by analyzing the available
Transiting Exoplanet Survey Satellite (TESS) photometry.
We derived RV, vsini, and atmospheric parameters for 1581 spectra
of 283 stars. Literature data were used to assess the accuracy of the
derived parameters. The RV distribution of the cluster members peaks
at 5.0km/s with a dispersion of 1.4km/s, while the average metallicity
is [Fe/H]=-0.03±0.06, in line with previous determinations.
Fitting empirical isochrones of Li depletion to EW measures of stars
with Teff<6500K, we obtain a reliable age for the Pleiades of
118±6Myr, in agreement with the recent literature.
The activity indicators H-alpha line flux (FHa) and luminosity ratio
(R'Ha) show the hottest stars to be less active, on average, than
the coldest ones, as expected for a 100-Myr old cluster. When plotted
against the Rossby number RO, our R'Ha values display the typical
trend with a steep decay for RO>0.2 and a nearly flat (saturated)
activity level for smaller values. However, we still see a slight
dependence on RO in the saturated regime which is well fitted by a
power law with a slope of -0.18±0.02, in agreement with some
previous work.
For three sources with multi-epoch data we have found LAMOST spectra
acquired during flares, which are characterized by strong and broad
H-alpha profiles and the presence of the HeI-6678 emission line. Among
our targets we identify 39 possible SB1 and ten SB2 systems. We have
also shown the potential of the LAMOST-MRS spectra, which allowed us
to refine the orbital solution of some binary and to discover a new
double-lined binary.
Description:
Spectral type, average atmospheric parameters (Teff, logg, and
[Fe/H]), radial velocity (RV) and projected rotational velocity
(vsini) are quoted in Table 1 for 283 stars.
Table 3 reports the H-alpha equivalent width, flux at the stellar
surface and luminosity ratio R'Ha for 271 targets.
Table 4 reports the LiI-6708 equivalent width and lithium abundance
for 276 targets.
Table A.2 lists the RV measured in each of the individual spectra
reporting also the measures for the blue and red arm before correcting
and combining them.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 152 283 Stellar parameters of the investigated sources
table3.dat 121 271 Chromospheric activity indicators
table4.dat 120 276 Lithium equivalent widths and abundances
tablea2.dat 159 1514 Radial velocities for individual spectra
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See also:
J/A+A/594/A39 : LAMOST-Kepler parameters & activity indicators (Frasca+, 2016)
J/A+A/664/A78 : Kepler targets class based on LAMOST spectra (Frasca+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.6 deg RAdeg Right ascension (J2000)
11- 19 F9.6 deg DEdeg Declination (J2000)
22- 39 I18 --- GaiaDR3 Gaia DR3 source_id (source_id)
42- 46 I5 K Teff ?=-999 Effective temperature
49- 52 I4 K e_Teff ?=-999 Effective temperature error
56- 59 F4.2 [cm/s2] logg ?=9.99 Logarithm of surface gravity
63- 66 F4.2 [cm/s2] e_logg ?=9.99 Error on logarithm of surface gravity
70- 74 F5.2 [Sun] [Fe/H] ?=9.99 Iron abundance relative to the Sun
77- 81 F5.2 [Sun] e_[Fe/H] ?=9.99 Error on iron abund relative
to the Sun
84 A1 --- l_vsini Limit flag on vsini
85- 89 F5.1 km/s vsini ?=-9.9 Projected rotational velocity
92- 95 F4.1 km/s e_vsini ?=-9.9 Projected rotational velocity error
97-103 A7 --- SpType Spectral type in MK or HD
107 A1 --- Sub Subsample (G1)
109-114 F6.2 km/s HRV ?=99.99 Average heliocentric radial velocity
117-121 F5.2 km/s e_HRV ?=99.99 Heliocentric radial velocity error
124-131 F8.5 --- P(chi2) Chi-square probability for RV variations
134-140 F7.4 d Prot ?=-9.9999 Rotational period
142 A1 --- r_Prot [RT] Reference for Prot (2)
144-152 A9 --- Remarks Remarks of RV variability (3)
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Note (2): Reference for Prot as follows:
R = K2-Kepler from Rebull et al. (2016AJ....152..114R 2016AJ....152..114R, Cat. J/AJ/152/114)
T = TESS Present work
Note (3): Remarks of RV as follows:
RVvar = Significantly variable RV (P(chi2)<0.05)
SB2 = Double-lined spectroscopic binary
SB1 = Single-lined spectroscopic binary
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Target Target designation (JHHMMSS.ss+DDMMSS.s)
22- 39 I18 --- GaiaDR3 Gaia DR3 source_id (source_id)
41- 45 I5 K Teff Effective temperature
47- 50 I4 K e_Teff Effective temperature error
54- 57 F4.2 [cm/s2] logg Logarithm of surface gravity
60- 63 F4.2 [cm/s2] e_logg Error on logarithm of surface gravity
67 A1 --- l_EWHa ? Limit flag on Hα equivalent width
68- 74 F7.3 0.1nm EWHa Hα equivalent width
77- 82 F6.3 0.1nm e_EWHa ?=9.999 Hα equivalent width error
87- 95 E9.2 mW/m2 FHa Hα flux
98-106 E9.2 mW/m2 e_FHa ?=9.999 Hα flux error
108-113 F6.2 --- logR'Ha log(LHα/Lbol) (1)
116-119 F4.2 --- e_logR'Ha ?=9.99 Error of log(LHα/Lbol) (1)
121 A1 --- Sub Subsample (G1)
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Note (1): logR'Ha = logarithm of luminosity ratio Hα/Bolometric.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Target Target designation (JHHMMSS.ss+DDMMSS.s)
22- 39 I18 --- GaiaDR3 Gaia DR3 source_id (source_id)
42- 51 F10.6 deg RAdeg Right ascension (J2000)
54- 63 F10.6 deg DEdeg Declination (J2000)
66- 70 I5 K Teff ? Effective temperature
72- 75 I4 K e_Teff ? Effective temperature error
79- 82 F4.2 [cm/s2] logg ? Logarithm of surface gravity
86- 89 F4.2 [cm/s2] e_logg ? Error on logarithm of surface gravity
93 A1 --- l_EW(Li) ? Limit flag on EW(Li)
94- 97 I4 0.1pm EW(Li) ? Lithium equivalent width
101-103 I3 0.1pm e_EW(Li) ? rms uncertainty on EW(Li)
107-111 F5.2 [-] A(Li) ?=-9.99 Lithium abundance
115-118 F4.2 [-] e_A(Li) ?=0.00 error on A(Li)
120 A1 --- Sub Subsample (G1)
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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- 19 A19 --- Target Target designation (JHHMMSS.ss+DDMMSS.s)
22- 39 I18 --- GaiaDR3 Gaia DR3 source_id (source_id)
42- 51 F10.6 deg RAdeg Right ascension (J2000)
54- 63 F10.6 deg DEdeg Declination (J2000)
65- 76 F12.5 d HJD Reduced heliocentric Julian day (HJD-2400000)
79-116 A38 --- SpName LAMOST spectrum name
118-123 F6.2 km/s HRVred ?=99.99 Heliocentric radial velocity red arm
126-130 F5.2 km/s e_HRVred ?=99.99 Heliocentric radial velocity red error
132-137 F6.2 km/s HRVblu ?=99.99 Heliocentric radial velocity blue arm
140-144 F5.2 km/s e_HRVblu ?=99.99 Heliocentric radial velocity blue error
146-151 F6.2 km/s HRVcor ?=99.99 Corrected heliocentric radial velocity
153-157 F5.2 km/s e_HRVcor ?=99.99 Corrected heliocentric RV error
159 A1 --- Sub Subsample (G1)
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Global notes:
Note (G1): Subsample as follows:
C = Cantat
H = Hunt
R = Rebull
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Acknowledgements:
Antonio Frasca, antonio.frasca(at)inaf.it
(End) Patricia Vannier [CDS] 14-Apr-2025