J/MNRAS/483/3196 GALAH carbon-enhanced stars & CEMP candidates (Cotar+, 2019)
The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates.
Cotar K., Zwitter T., Kos J., Munari U., Martell S.L., Asplund M.,
Bland-Hawthorn J., Buder S., de Silva G.M., Freeman K.C., Sharma S.,
Anguiano B., Carollo D., Horner J., Lewis G.F., Nataf D.M., Nordlander T.,
Stello D., Ting Y.-S., Tinney C., Traven G., Wittenmyer R.A.,
Galah Collaboration
<Mon. Not. R. Astron. Soc. 483, 3196-3212 (2019)>
=2019MNRAS.483.3196C 2019MNRAS.483.3196C (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Stars, carbon ; Effective temperatures ;
Abundances, [Fe/H]
Keywords: methods: data analysis - catalogues - stars: abundances -
stars: carbon
Abstract:
Swan bands - characteristic molecular absorption features of the C2
molecule - are a spectroscopic signature of carbon-enhanced stars.
They can also be used to identify carbon-enhanced metal-poor (CEMP)
stars. The GALAH (GALactic Archaeology with Hermes) is a
magnitude-limited survey of stars producing high-resolution,
high-signal-to-noise spectra. We used 627708 GALAH spectra to search
for carbon-enhanced stars with a supervised and unsupervised
classification algorithm, relying on the imprint of the Swan bands. We
identified 918 carbon-enhanced stars, including 12 already described
in the literature. An unbiased selection function of the GALAH survey
allows us to perform a population study of carbon-enhanced stars. Most
of them are giants, out of which we find 28 CEMP candidates. A large
fraction of our carbon-enhanced stars with repeated observations show
variation in radial velocity, hinting that there is a large fraction
of variables among them. 32 of the detected stars also show strong
Lithium enhancement in their spectra.
Description:
The analysed set of stellar spectra was acquired by the High
Efficiency and Resolution Multi-Element Spectrograph (HERMES), a
fibre-fed multi-object spectrograph on the 3.9m Anglo-Australian
Telescope (AAT) of the Australian Astronomical Observatory.
Spectra used in this study have been taken from multiple different
observing programmes using this spectrograph: the GALactic Archaeology
with HERMES (GALAH) pilot survey (Duong et al., 2018MNRAS.476.5216D 2018MNRAS.476.5216D),
the main GALAH survey (De Silva et al., 2015MNRAS.449.2604D 2015MNRAS.449.2604D), the
K2-HERMES survey (Wittenmyer et al. 2016 , AAS Meeting Abstracts
#227), and the TESS-HERMES survey (Sharma et al.,
2018MNRAS.473.2004S 2018MNRAS.473.2004S).
Our data set consists of 627708 successfully reduced spectra of
576229 stars observed between 2013 November and 2018 February.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
galah-cc.dat 258 1026 GALAH carbon CEMP catalogue of detected objects and
objects matched with multiple literature sources
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See also:
III/227 : General Catalog of galactic Carbon stars, 3d Ed.
(Alksnis+ 2001)
J/ApJS/105/419 : Spectral Atlas of Carbon Stars (Barnbaum+ 1996)
J/other/Ap/41.356 : FBS 10th list of red stars (Gigoyan+, 1998)
J/AJ/124/1651 : Faint high-latitude carbon stars SDSS photom.
(Margon+, 2002)
J/AJ/127/2838 : Faint high-latitude carbon stars SDSS photom.
(Downes+, 2004)
J/A+A/473/143 : RVs of C stars near Galactic plane (Demers+, 2007)
J/ApJ/765/12 : Carbon stars & DQ white dwarfs from SDSS-DR7+DR8
(Green, 2013)
J/other/RAA/15.1671 : New carbon stars from LAMOST survey (Si+, 2015)
J/A+A/589/A36 : Carbon stars spectra and photometry values
(Gonneau+, 2016)
http://galah-survey.org/ : GALAH home page
Byte-by-byte Description of file: galah-cc.dat
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Bytes Format Units Label Explanations
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1- 20 I20 --- GaiaDR2 ?=- Gaia DR2 identifier (source_id)
22- 36 I15 --- GALAH GALAH unique per observation id
38- 52 F15.11 deg RAdeg Right ascension from 2MASS (J2000)
54- 70 F17.13 deg DEdeg Declination from 2MASS (J2000)
72 A1 --- detsup [FT] Detected by supervised fitting method
(T=true)
74 A1 --- detusup [FT] Detected by t-SNE method (T=true)
76- 92 E17.12 --- swaninteg ? Swan band strength if determined
94-106 F13.8 K Teff ?=- The Cannon effective temperature Teff
108-122 F15.10 K e_Teff ?=- rms uncertainty on Teff
124-138 F15.12 [cm/s2] logg ?=- The Cannon surface gravity logg
140-154 F15.13 [cm/s2] e_logg ?=- rms uncertainty on logg
156-172 F17.14 [-] [Fe/H] ?=- The Cannon iron abundance [Fe/H]
174-188 F15.13 [-] e_[Fe/H] ?=- rms uncertainty on [Fe/H]
191-192 I2 --- flagcannon ?=- The Cannon flags in a bit
mask format (1)
194 A1 --- type [D/G-] G for giants and D for dwarfs
196 A1 --- rvvar [FT] Is radial velocity variable (T=true)
198 A1 --- cempcand [FT] Is star CEMP candidate (T=true)
200-258 A59 --- Refs Bibcode(s) of the literature match
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Note (1): Flags indicating difficulty in abundance determination in a bitmask
format 0=No flag recommended.
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Acknowledgements:
Klemen Cotar, klemen.cotar(at)fmf.uni-lj.si
(End) Patricia Vannier [CDS] 01-Jan-2019