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γ Columbae as a recently stripped pulsating core of a massive star

Nature Astronomy volume 6, pages 1414–1420 (2022)Cite this article

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Abstract

Stellar cores, that is, the central regions where densities and temperatures are high enough for nuclear fusion processes to take place, are usually covered by an opaque envelope. Only in very rare cases, stars may expose their cores, for example, when a tiny fraction of them evolve into Wolf–Rayet or helium hot subdwarf stars. However, for the vast majority of stars, namely unevolved stars that burn hydrogen into helium in their centres, direct observational clues on the cores are still missing. On the basis of a spectroscopic and photometric analyses, here we show that the bright B-type-star γ Columbae is the stripped pulsating core (with a mass of 4–5 M⊙, where M⊙ is the mass of the Sun) of a previously much more massive star of roughly 12 M⊙ that just finished central hydrogen fusion. The discovery of this star, which is still in a short-lived post-stripping structural re-adjustment phase, paves the way to obtain invaluable insights into the physics of both single and binary stars with respect to nuclear astrophysics and common-envelope evolution. In particular, it provides observational constraints on the structure and evolution of stripped-envelope stars.

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Fig. 1: Observational signature of the peculiar abundances of carbon and nitrogen.
Fig. 2: Comparison with CNO signatures from other stars.
Fig. 3: Comparison between observed abundances and theoretical predictions for the depth-dependent chemical composition in a massive star.
Fig. 4: Stellar evolution in the Hertzsprung–Russell diagram.

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Data availability

The astrometric, photometric and spectroscopic data used in this work are all publicly available via the cited sources.

Code availability

All codes/routines used in this work are publicly documented, but not publicly available.

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Acknowledgements

G.M. thanks the Swiss National Science Foundation (project number 200020-205154). G.M. has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 833925, project STAREX). We thank U. Heber and M. Sasaki for discussions and J. E. Davis for the development of the SLXFIG module that was used to prepare the figures in this paper. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 080.D-0333(A), 182.D-0356(C), 088.A-9003(A) and 090.D-0358(A). Based on observations obtained at the Canada–France–Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientique of France and the University of Hawaii. Funding for the TESS mission is provided by NASA’s Science Mission directorate. This paper includes data collected by the TESS mission, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). Some of the data presented in this paper were obtained from MAST. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC; https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.

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Authors and Affiliations

  1. Dr. Karl Remeis-Observatory and ECAP, Friedrich-Alexander University Erlangen-Nuremberg, Bamberg, Germany

    Andreas Irrgang

  2. Institut für Astro- und Teilchenphysik, Universität Innsbruck, Innsbruck, Austria

    Norbert Przybilla

  3. Geneva Observatory, University of Geneva, Sauverny, Switzerland

    Georges Meynet

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All authors contributed to the work presented in this paper and to the writing of the manuscript. A.I. carried out the photometric, spectroscopic and astrometric analysis, the results of which were primarily interpreted by N.P. G.M. calculated the tailored stellar evolution model.

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Correspondence to Andreas Irrgang.

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Irrgang, A., Przybilla, N. & Meynet, G. γ Columbae as a recently stripped pulsating core of a massive star. Nat Astron 6, 1414–1420 (2022). https://doi.org/10.1038/s41550-022-01809-6

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