The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission

Cotar, Klemen and Zwitter, Tomaz and Traven, Gregor and Kos, Janez and Asplund, Martin and Bland-Hawthorn, Joss and Buder, Sven and D'Orazi, Valentina and de Silva, Gayandhi M. and Lin, Jane and Martell, Sarah L. and Sharma, Sanjib and Simpson, Jeffrey D. and Zucker, Daniel B. and Horner, Jonathan and Lewis, Geraint F. and Nordlander, Thomas and Ting, Yuan-Sen and Wittenmyer, Rob A. and Galah Collaboration, Galah Collaboration (2019) The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission. Monthly Notices of the Royal Astronomical Society, 487 (2). pp. 2474-2490. ISSN 0035-8711

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Abstract

The latest Gaia data release enables us to accurately identify stars that are more luminous than would be expected on the basis of their spectral type and distance. During an investigation of the 329 best solar twin candidates uncovered among the spectra acquired by the GALAH survey, we identified 64 such overluminous stars. In order to investigate their exact composition, we developed a data-driven methodology that can generate a synthetic photometric signature and spectrum of a single star. By combining multiple such synthetic stars into an unresolved binary or triple system and comparing the results to the actual photometric and spectroscopic observations, we uncovered 6 definitive triple stellar system candidates and an additional 14 potential candidates whose combined spectrum mimics the solar spectrum. Considering the volume correction factor for a magnitude-limited survey, the fraction of probable unresolved triple stars with long orbital periods is ̃2 per cent. Possible orbital configurations of the candidates were investigated using the selection and observational limits. To validate the discovered multiplicity fraction, the same procedure was used to evaluate the multiplicity fraction of other stellar types.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 27 Jan 2020 23:34
Last Modified: 07 Feb 2020 01:25
Uncontrolled Keywords: methods: data analysis; binaries: general; stars: solar-type; Galaxy:; stellar content; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: 10.1093/mnras/stz1397
URI: http://eprints.usq.edu.au/id/eprint/37415

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