$\gamma$ Columbae: the recently stripped, pulsating core of a massive star

Abstract

A vital condition for life on Earth is the steady supply of radiative heat by the Sun. Like all other stars, the Sun generates its emitted energy in its central regions where densities and temperatures are high enough for nuclear fusion processes to take place. Because stellar cores are usually covered by an opaque envelope, most of our knowledge about them and their life-giving nuclear processes comes from theoretical modelling or from indirect observations such as the detection of solar neutrinos and the study of stellar pulsations, respectively. Only in very rare cases, stars may expose their cores, e.g., when a tiny fraction of them evolves into Wolf-Rayet or helium hot subdwarf stars. However, for the vast majority of stars, namely unevolved stars that burn hydrogen to helium in their centres, direct observational clues on the cores are still missing. Based on a comprehensive spectroscopic and asteroseismic analysis, we show here that the bright B-type star $\gamma$ Columbae is the stripped pulsating core (with a mass of $4$-$5M_{\odot }$, where $M_{\odot }$ is the mass of the Sun) of a previously much more massive star of roughly $12M_{\odot }$ that just finished central hydrogen fusion. The star's inferred parameters indicate that it is still in a short-lived post-stripping structural readjustment phase, making it an extremely rare object. The discovery of this unique star 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 first observational constraints on the structure and evolution of stripped envelope stars.

This preprint has not undergone peer review or any post-submission improvements or corrections. The Version of Record of this article is published in Nature Astronomy, and is available online at https://doi.org/10.1038/s41550-022-01809-6

References in corpus (18)

• The Transiting Exoplanet Survey Satellite
• Binary interaction dominates the evolution of massive stars
• Physical Properties of Wolf-Rayet Stars
• Gaia Early Data Release 3: Photometric content and validation
• Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models
• An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-Ultraviolet Extinction and Its R-Dependence
• The Evolution of Massive Helium Stars Including Mass Loss
• A wide star-black-hole binary system from radial-velocity measurements
• Internal mixing of rotating stars inferred from dipole gravity modes
• Populations of rotating stars III. SYCLIST, the new Geneva Population Synthesis code
• The MiMeS Survey of Magnetism in Massive Stars: CNO surface abundances of Galactic O stars
• Evolution of surface CNO abundances in massive stars
• Flux calibration of medium-resolution spectra from 300 nm to 2500 nm: Model reference spectra and telluric correction
• A naked-eye triple system with a nonaccreting black hole in the inner binary
• New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars
• The qWR star HD 45166. II. Fundamental stellar parameters and evidence of a latitude-dependent wind
• High-mass pulsators in eclipsing binaries observed using TESS
• Pulsational properties of ten new slowly pulsating B stars

Cited by in corpus (15)

• The ELM Survey South. II. Two dozen new low mass white dwarf binaries
• A partially stripped massive star in a Be binary at low metallicity: A missing link towards Be X-ray binaries and double neutron star mergers
• Clumping and X-Rays in cooler B supergiant stars
• The B-type Binaries Characterisation Programme II. VFTS 291: A stripped star from a recent mass transfer phase
• X-Shooting ULLYSES: Massive Stars at low metallicity VIII. Stellar and wind parameters of newly revealed stripped stars in Be binaries
• Binarity at Low Metallicity (BLOeM) -- Multiplicity properties of Oe and Be stars
• On the evolutionary nature of puffed-up stripped star binaries and their occurrence in stellar populations
• The mass distribution of stars stripped in binaries: The effect of metallicity
• SHOTGLAS II. MUSE spectroscopy of blue horizontal branch stars in the core of $\omega$ Centauri and NGC 6752
• The blue supergiant Sher 25 revisited in the Gaia era
• Newborn Be star systems observed shortly after mass transfer
• The first massive compact companion in a wide orbit around a hot subdwarf star
• Runaway BN supergiant star HD 93840: Progenitor of an imminent core-collapse supernova above the Galactic plane
• Quantitative spectroscopy of multiple OB stars: I. The quadruple system HD 37061 at the centre of Messier 43
• Chemical fingerprints of binary mass transfer in massive stars