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

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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.

Original languageEnglish
Pages (from-to)3196-3212
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume483
Issue number3
DOIs
Publication statusPublished - 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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