The GALAH survey: effective temperature calibration from the InfraRed Flux Method in the Gaia system

Luca Casagrande*, Jane Lin, Adam D. Rains, Fan Liu, Sven Buder, Jonathan Horner, Martin Asplund, Geraint F. Lewis, Sarah L. Martell, Thomas Nordlander, Dennis Stello, Yuan Sen Ting, Robert A. Wittenmyer, Joss Bland-Hawthorn, Andrew R. Casey, Gayandhi M. De Silva, Valentina D'Orazi, Ken C. Freeman, Michael R. Hayden, Janez KosKarin Lind, Katharine J. Schlesinger, Sanjib Sharma, Jeffrey D. Simpson, Daniel B. Zucker, Tomaž Zwitter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)
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In order to accurately determine stellar properties, knowledge of the effective temperature of stars is vital. We implement Gaia and 2MASS photometry in the InfraRed Flux Method and apply it to over 360 000 stars across different evolutionary stages in the GALAH DR3 survey. We derive colour-effective temperature relations that take into account the effect of metallicity and surface gravity over the range 4000 K ≲ Teff ≲ 8000 K, from very metal-poor stars to supersolar metallicities. The internal uncertainty of these calibrations is of order 40-80 K depending on the colour combination used. Comparison against solar-twins, Gaia benchmark stars, and the latest interferometric measurements validates the precision and accuracy of these calibrations from F to early M spectral types. We assess the impact of various sources of uncertainties, including the assumed extinction law, and provide guidelines to use our relations. Robust solar colours are also derived.

Original languageEnglish
Pages (from-to)2684-2696
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Publication statusPublished - 1 Oct 2021

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 507, Issue 2, October 2021, Pages 2684–2696, Copyright 2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


  • infrared: stars
  • stars: abundances
  • stars: atmospheres
  • stars: fundamental parameters
  • stars: Hertzsprung-Russell and colour-magnitude diagrams
  • techniques: photometric


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