The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates

GALAH collaboration; Klemen Čotar; Tomaž Zwitter; Janez Kos; Ulisse Munari; Sarah L. Martell; Martin Asplund; Joss Bland-Hawthorn; Sven Buder; Gayandhi M. De Silva; Kenneth C. Freeman; Sanjib Sharma; Borja Anguiano; Daniela Carollo; Jonathan Horner; Geraint F. Lewis; David M. Nataf; Thomas Nordlander; Denis Stello; Yuan-Sen Ting; Chris Tinney; Gregor Traven; Rob A. Wittenmyer

doi:10.1093/mnras/sty3155

The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates

GALAH collaboration, Klemen Čotar^*, Tomaž Zwitter, Janez Kos, Ulisse Munari, Sarah L. Martell, Martin Asplund, Joss Bland-Hawthorn, Sven Buder, Gayandhi M. De Silva, Kenneth C. Freeman, Sanjib Sharma, Borja Anguiano, Daniela Carollo, Jonathan Horner, Geraint F. Lewis, David M. Nataf, Thomas Nordlander, Denis Stello, Yuan-Sen TingChris Tinney, Gregor Traven, Rob A. Wittenmyer

^*Corresponding author for this work

Australian Astronomical Optics

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Abstract

Swan bands - characteristic molecular absorption features of the C₂molecule - are a spectroscopic signature of carbon-enhanced stars. They can also be used to identify carbonenhanced 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 627 708 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.

Original language	English
Pages (from-to)	3196-3212
Number of pages	17
Journal	Monthly Notices of the Royal Astronomical Society
Volume	483
Issue number	3
DOIs	https://doi.org/10.1093/mnras/sty3155
Publication status	Published - Mar 2019

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, March 2019, Pages 3196–3212, https://doi.org/10.1093/mnras/sty3155. Copyright 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Keywords

Catalogues
Methods: data analysis
Stars: abundances
Stars: carbon

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10.1093/mnras/sty3155

Publisher version (open access)Final published version, 27.5 MBLicence: Other

Cite this

GALAH collaboration, Čotar, 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., ... Wittenmyer, R. A. (2019). The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates. Monthly Notices of the Royal Astronomical Society, 483(3), 3196-3212. https://doi.org/10.1093/mnras/sty3155

@article{64d4ac62fe5f441ba2d1165908aeabe1,

title = "The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates",

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 carbonenhanced 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 627 708 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.",

keywords = "Catalogues, Methods: data analysis, Stars: abundances, Stars: carbon",

author = "{GALAH collaboration} and Klemen {\v C}otar and Toma{\v z} Zwitter and Janez Kos and Ulisse Munari and Martell, {Sarah L.} and Martin Asplund and Joss Bland-Hawthorn and Sven Buder and {De Silva}, {Gayandhi M.} and Freeman, {Kenneth C.} and Sanjib Sharma and Borja Anguiano and Daniela Carollo and Jonathan Horner and Lewis, {Geraint F.} and Nataf, {David M.} and Thomas Nordlander and Denis Stello and Yuan-Sen Ting and Chris Tinney and Gregor Traven and Wittenmyer, {Rob A.}",

note = "This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, March 2019, Pages 3196–3212, https://doi.org/10.1093/mnras/sty3155. Copyright 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.",

year = "2019",

month = mar,

doi = "10.1093/mnras/sty3155",

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volume = "483",

pages = "3196--3212",

journal = "Monthly Notices of the Royal Astronomical Society",

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GALAH collaboration, Čotar, K, Zwitter, T, Kos, J, Munari, U, Martell, SL, Asplund, M, Bland-Hawthorn, J, Buder, S, De Silva, GM, Freeman, KC, Sharma, S, Anguiano, B, Carollo, D, Horner, J, Lewis, GF, Nataf, DM, Nordlander, T, Stello, D, Ting, Y-S, Tinney, C, Traven, G & Wittenmyer, RA 2019, 'The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates', Monthly Notices of the Royal Astronomical Society, vol. 483, no. 3, pp. 3196-3212. https://doi.org/10.1093/mnras/sty3155

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T2 - a catalogue of carbon-enhanced stars and CEMP candidates

AU - GALAH collaboration

AU - Čotar, Klemen

AU - Zwitter, Tomaž

AU - Kos, Janez

AU - Munari, Ulisse

AU - Martell, Sarah L.

AU - Asplund, Martin

AU - Bland-Hawthorn, Joss

AU - Buder, Sven

AU - De Silva, Gayandhi M.

AU - Freeman, Kenneth C.

AU - Sharma, Sanjib

AU - Anguiano, Borja

AU - Carollo, Daniela

AU - Horner, Jonathan

AU - Lewis, Geraint F.

AU - Nataf, David M.

AU - Nordlander, Thomas

AU - Stello, Denis

AU - Ting, Yuan-Sen

AU - Tinney, Chris

AU - Traven, Gregor

AU - Wittenmyer, Rob A.

N1 - This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, March 2019, Pages 3196–3212, https://doi.org/10.1093/mnras/sty3155. Copyright 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

PY - 2019/3

Y1 - 2019/3

N2 - 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 carbonenhanced 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 627 708 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.

AB - 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 carbonenhanced 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 627 708 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.

KW - Catalogues

KW - Methods: data analysis

KW - Stars: abundances

KW - Stars: carbon

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UR - http://purl.org/au-research/grants/arc/CE170100013

U2 - 10.1093/mnras/sty3155

DO - 10.1093/mnras/sty3155

M3 - Article

SN - 0035-8711

VL - 483

SP - 3196

EP - 3212

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -

The GALAH survey: a catalogue of carbon-enhanced stars and CEMP candidates

Abstract

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Keywords

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