The convective surface of the red supergiant Antares. VLTI/PIONIER interferometry in the near infrared

Abstract

Context. Convection is a candidate to explain the trigger of red supergiant star mass loss. Owing to the small size of the convective cells on the photosphere, few of their characteristics are known. Aims. Using near infrared interferometry, we intend to resolve the photosphere of red supergiant stars and to bring new constraints on their modeling. Methods. We observed the nearby red supergiant Antares using the 4-telescope instrument VLTI/PIONIER. We collected data on the three available configurations of the 1.8m telescopes in the H band. Results. We obtained unprecedented angular resolution on the disk of a star (6% of the star angular diameter) that limits the mean size of convective cells, brings new constraints on numerical simulations. Using an analytical model with a distribution of bright spots we determine their effect on the visibility signal. Conclusion. We determine that the interferometric signal on Antares is compatible with convective cells with various sizes from 45% to 5% of the angular diameter. We also conclude that convective cells can strongly affect the angular diameter and limb-darkening measurements. In particular, the apparent angular diameter becomes dependent on the sampled position angles.

13 pages, 10 figures. Accepted for publication in Astronomy & Astrophysics. Language editing and typo corrections

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Cited by in corpus (7)

• Optical interferometry and Gaia measurement uncertainties reveal the physics of asymptotic giant branch stars
• The inner circumstellar dust of the red supergiant Antares as seen with VLT/SPHERE/ZIMPOL
• The Betelgeuse Project II: Asteroseismology
• One month convection timescale on the surface of a giant evolved star
• Perspectives of a visible instrument on the VLTI
• Crosstalk in image plane beam combination for optical interferometers
• First images of Antares photosphere from spectropolarimetry