J/A+A/594/A39 LAMOST-Kepler parameters and activity indicators (Frasca+, 2016)
Activity indicators and stellar parameters of the Kepler targets.
An application of the ROTFIT pipeline to LAMOST-Kepler stellar spectra.
Frasca A., Molenda-Zakowicz J., De Cat P., Catanzaro G., Fu J.N.,
Ren A.B., Luo A.L., Shi J.R., Wu Y., Zhang H.T.
<Astron. Astrophys. 594, A39 (2016)>
=2016A&A...594A..39F 2016A&A...594A..39F (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Effective temperatures ; Radial velocities ;
Equivalent widths
Keywords: surveys - techniques: spectroscopic - stars: fundamental parameters -
stars: kinematics and dynamics - stars: activity -
stars: chromospheres
Abstract:
A comprehensive and homogeneous determination of stellar parameters
for the stars observed by the Kepler space telescope is necessary for
statistical studies of their properties.
As a result of the large number of stars monitored by Kepler, the
largest and more complete databases of stellar parameters published to
date are multiband photometric surveys.
The LAMOST-Kepler survey, whose spectra are analyzed in the present
paper, was the first large spectroscopic project, which started in
2011 and aimed at filling that gap.
In this work we present the results of our analysis, which is focused
on selecting spectra with emission lines and chromospherically active
stars by means of the spectral subtraction of inactive templates. The
spectroscopic determination of the atmospheric parameters for a large
number of stars is a by-product of our analysis.
We have used a purposely developed version of the code ROTFIT for the
determination of the stellar parameters by exploiting a wide and
homogeneous collection of real star spectra, namely the Indo US
library.
We provide a catalog with the atmospheric parameters (Teff, logg, and
[Fe/H]), radial velocity (RV), and an estimate of the projected
rotation velocity (vsini). For cool stars (Teff<6000K), we also
calculated the H-alpha and CaII-IRT fluxes, which are important
proxies of chromospheric activity.
We have derived the RV and atmospheric parameters for 61753 spectra
of 51385 stars.
The average uncertainties, which we estimate from the stars observed
more than once, are about 12km/s, 1.3%, 0.05dex, and 0.06dex for
RV, Teff, logg, and [Fe/H], respectively, although they are larger for
the spectra with a very low signal-to-noise ratio.
Literature data for a few hundred stars (mainly from high-resolution
spectroscopy) were used to peform quality control of our results. The
final accuracy of the RV is about 14km/s.
The accuracy of the Teff, logg, and [Fe/H] measurements is about 3.5%,
0.3dex, and 0.2dex, respectively.
However, while the Teff values are in very good agreement with the
literature, we noted some issues with the determination of [Fe/H] of
metal poor stars and the tendency, for logg, to cluster around the
values typical for main-sequence and red giant stars. We propose
correction relations based on these comparisons and we show that this
does not have a significant effect on the determination of the
chromospheric fluxes.
The RV distribution is asymmetric and shows an excess of stars with
negative RVs that are larger at low metallicities. Despite the rather
low LAMOST resolution, we were able to identify interesting and
peculiar objects, such as stars with variable RV, ultrafast rotators,
and emission-line objects. Based on the H-alpha and CaII-IRT fluxes,
we found 442 chromospherically active stars, one of which is a likely
accreting object.
The availability of precise rotation periods from the Kepler
photometry allowed us to study the dependency of these chromospheric
fluxes on the rotation rate for a very large sample of field stars.
Description:
Spectral type, atmospheric parameters (Teff, logg, and [Fe/H]), radial
velocity (RV) and projected rotational velocity (vsini) are quoted in
Table A.3.
Table A.4 reports the H-alpha and CaII-IRT equivalent widths for 577
spectra of 547 targets.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea3.dat 173 61753 Stellar parameters
tablea4.dat 145 577 Activity indicators
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 43 A43 --- SpName LAMOST spectrum name
45- 54 F10.4 d HJD Reduced Heliocentric Julian day
(HJD-2400000)
56- 63 I8 --- KIC Kepler Input Catalog number
65- 67 I3 --- S/Nr Signal-to-noise ratio in r band
69- 79 F11.7 deg RAdeg Right ascention (J2000)
81- 91 F11.7 deg DEdeg Declination (J2000)
93-106 A14 --- SpType Spectral type in MK or HD
108-112 I5 K Teff Effective temperature
114-117 I4 K e_Teff Effective temperature error
119-122 F4.2 [cm/s2] logg Logarithm of surface gravity
124-127 F4.2 [cm/s2] e_logg Error on logarithm of surface gravity
129-133 F5.2 [Sun] [Fe/H] Iron abundance relative to the Sun
135-138 F4.2 [Sun] e_[Fe/H] Error on iron abundance relative to the Sun
140-145 F6.1 km/s HRV ?=- Heliocentric Radial Velocity
147-150 F4.1 km/s e_HRV ?=- Heliocentric Radial Velocity error
152 A1 --- l_vsini Limit flag on vsini
153-155 I3 km/s vsini Projected rotational velocity
157-159 I3 km/s e_vsini ? Projected rotational velocity error
161-167 F7.4 --- P(chi2) Chi-square probability for RV variations
169-173 F5.2 [Sun] [Fe/H]cor Corrected iron abundance relative to
the Sun (1)
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Note (1): [Fe/H] corrected according to Eq. 1, [Fe/H]cor=2.16*[Fe/H]+0.17.
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Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 43 A43 --- SpName LAMOST spectrum name
45- 55 F11.5 d HJD Reduced Heliocentric Julian day (HJD-2400000)
57- 64 I8 --- KIC Kepler Input Catalog number
66- 75 F10.6 deg RAdeg Right Ascention (J2000)
77- 86 F10.6 deg DEdeg Declination (J2000)
88- 92 F5.2 0.1nm EWHa ?=- Hα equivalent width
94- 97 F4.2 0.1nm e_EWHa ?=- Hα equivalent width error
99-103 F5.2 0.1nm EW8498 ?=- CaII-8498 equivalent width
105-108 F4.2 0.1nm e_EW8498 ?=- CaII-8498 equivalent width error
110-114 F5.2 0.1nm EW8542 ?=- CaII-8542 equivalent width
116-119 F4.2 0.1nm e_EW8542 ?=- CaII-8542 equivalent width error
121-125 F5.2 0.1nm EW8662 ?=- CaII-8542 equivalent width
127-130 F4.2 0.1nm e_EW8662 ?=- CaII-8542 equivalent width error
132-133 A2 --- n_EWHa [END ] Hα behavior (1)
135-140 F6.3 d Prot ? Rotational period
142-145 A4 --- r_Prot Reference for Prot (2)
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Note (1): Notes as follows:
E = Hα emission above the continuum
N = [NII] nebular lines
D = Doubtful Hα core filling
Note (2): Notes as follows:
D11 = Debosscher et al. (2011, Cat. J/A+A/529/A89)
N13 = Nielsen et al. (2015A&A...582A..10N 2015A&A...582A..10N
R13 = Reinhold et al. (2013, Cat. J/A+A/560/A4)
Mc13 = McQuillan et al. (2013, Cat. J/ApJ/775/L11)
Mc14 = McQuillan et al. (2014, Cat. J/ApJS/211/24)
M15 = Mazeh et al. (2015, Cat. J/ApJ/801/3)
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Acknowledgements:
Antonio Frasca, antonio.frasca(at)oact.inaf.it
History:
07-Oct-2016: on-line version
11-Dec-2017: First 4 KIC numbers corrected (from author)
(End) Antonio Frasca [INAF-OACt, Italy], Patricia Vannier [CDS] 18-Jul-2016