Imaging the spinning gas and dust in the disc around the supergiant A[e] star HD 62623
Astronomy and Astrophysics
Context. To progress in the understanding of evolution of massive stars one needs to constrain the mass-loss and determine the phenomenon responsible for the ejection of matter an its reorganization in the circumstellar environment. Aims. In order to test various mass-ejection processes, we probed the geometry and kinematics of the dust and gas surrounding the A[e] supergiant HD 62623. Methods. We used the combined high spectral and spatial resolution offered by the VLTI/AMBER instrument. Thanks to a new multiwavelength optical/IR interferometry imaging technique, we reconstructed the first velocity-resolved images with a milliarcsecond resolution in the infrared domain. Results. We managed to disentangle the dust and gas emission in the HD 62623 circumstellar disc. We measured the dusty disc inner inner rim, i.e. 6 mas, constrained the inclination angle and the position angle of the major-axis of the disc. We also measured the inner gaseous disc extension (2 mas) and probed its velocity field thanks to AMBER high spectral resolution. We find that the expansion velocity is negligible, and that Keplerian rotation is a favoured velocity field. Such a velocity field is unexpected if fast rotation of the central star alone is the main mechanism of matter ejection. Conclusions. As the star itself seems to rotate below its breakup-up velocity, rotation cannot explain the formation of the dense equatorial disc. Moreover, as the expansion velocity is negligible, radiatively driven wind is also not a suitable explanation to explain the disc formation. Consequently, the most probable hypothesis is that the accumulation of matter in the equatorial plane is due to the presence of the spectroscopic low mass companion
The Programme National de Physique Stellaire (PNPS), the Institut National en Sciences de l’Univers (INSU), and the Max Planck Institute for Radioastronomy (MPIfR) are acknowledged for their financial and observing time support. This research has made use of services from the Centre de Donn´ees de Strasbourg (CDS), from the Jean-Marie Mariotti Centre (JMMC), and from the NASA Exoplanet Science Institute (NExScI) to prepare and interpret the observations.
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.
Vol. 526, A107