Tomography of cool giant and supergiant star atmospheres

  title={Tomography of cool giant and supergiant star atmospheres},
  author={Kateryna Kravchenko and Andrea Chiavassa and Sophie Van Eck and Alain Jorissen and Thibault Merle and Bernd Freytag and Bertrand Plez},
  journal={Astronomy \& Astrophysics},
Context. Red supergiants are cool massive stars and are the largest and the most luminous stars in the Universe. They are characterized by irregular or semi-regular photometric variations, the physics of which is not clearly understood. Aims. The paper aims to derive the velocity field in the red supergiant star μ Cep and to relate it to the photometric variability with the help of the tomographic method. Methods. The tomographic method allows one to recover the line-of-sight velocity… 
Tomography of cool giant and supergiant star atmospheres. I. Validation of the method
Cool giant and supergiant star atmospheres are characterized by complex velocity fields originating from convection and pulsation processes which are not fully understood yet. The velocity fields
Tomography of cool giant and supergiant star atmospheres
Context. Asymptotic giant branch (AGB) stars are characterized by substantial mass loss, however the mechanism behind it not yet fully understood. The knowledge of the structure and dynamics of
Atmosphere of Betelgeuse before and during the Great Dimming event revealed by tomography
Context. Despite being the best studied red supergiant star in our Galaxy, the physics behind the photometric variability and mass loss of Betelgeuse is poorly understood. Moreover, recently the star
VLTI-PIONIER imaging of the red supergiant V602 Carinae
Context. Red supergiant stars possess surface features and extended molecular atmospheres. Photospheric convection may be a crucial factor of the levitation of the outer atmospheric layers. However,
Numerical Simulations of Convective Three-dimensional Red Supergiant Envelopes
We explore the three-dimensional properties of convective, luminous (L ≈ 104.5–105 L ⊙), hydrogen-rich envelopes of red supergiants (RSGs) based on radiation hydrodynamic simulations in spherical
Long Term Evolution of Surface Features on the Red Supergiant AZ Cyg
We present H-band interferometric observations of the red supergiant (RSG) AZ Cyg that were made with the Michigan Infra-Red Combiner (MIRC) at the six-telescope Center for High Angular Resolution
The nature of VX Sagitarii
Aims. We present a spectroscopic analysis of the extremely luminous red star VX Sgr based on high-resolution observations combined with AAVSO light curve data. Given the puzzling characteristics of
The Photospheric Temperatures of Betelgeuse during the Great Dimming of 2019/2020: No New Dust Required
The processes that shape the extended atmospheres of red supergiants (RSGs), heat their chromospheres, create molecular reservoirs, drive mass loss, and create dust remain poorly understood.
Effective temperatures of red supergiants estimated from line-depth ratios of iron lines in the YJ bands, 0.97-1.32μm
Determining the effective temperatures (Teff) of red supergiants (RSGs) observationally is important in many fields of stellar physics and galactic astronomy, yet some significant difficulties
A Massive Star’s Dying Breaths: Pulsating Red Supergiants and Their Resulting Type IIP Supernovae
Massive stars undergo fundamental-mode and first-overtone radial pulsations with periods of 100-1000 days as Red Supergiants (RSGs). At large amplitudes, these pulsations substantially modify the


Tomography of cool giant and supergiant star atmospheres. I. Validation of the method
Cool giant and supergiant star atmospheres are characterized by complex velocity fields originating from convection and pulsation processes which are not fully understood yet. The velocity fields
Vigorous atmospheric motion in the red supergiant star Antares
The two-dimensional velocity field map obtained from the near-infrared spectro-interferometric imaging reveals vigorous upwelling and downdrafting motions of several huge gas clumps at velocities ranging from about −20 to +20 kilometres per second in the atmosphere, which extends out to about 1.7 stellar radii.
Velocity Fields in Stellar Atmospheres Probed by Tomography
A tomographic method to probe velocity fields within stellar atmospheres is described. It relies on the design of spectral masks collecting lines forming at given, pre-specified ranges of optical
Global radiation-hydrodynamics simulations of red supergiant stars
The small-scale surface granulation on cool main-sequence stars and white dwarfs influences the overall appearance of these objects only weakly. And it is only indirectly observable by analyzing e.g.
Atmosphere tomography of red supergiant stars
3-D simulations suggest that the atmospheres of red super-giants are subject to large-amplitude convective motions, which are suspected to generate supersonic motions and shocks. We perform
Radiative hydrodynamics simulations of red supergiant stars - I. interpretation of interferometric observations
Context. It has been proposed that convection in red supergiant (RSG) stars produces large-scale granules causing observable surface inhomogeneities. This convection is also extremely vigorous and is
The effective temperature scale of galactic red supergiants : Cool, but not as cool as we thought
We use moderate-resolution optical spectrophotometry and the new MARCS stellar atmosphere models to determine the effective temperatures of 74 Galactic red supergiants (RSGs). The stars are mostly
Search for surface magnetic fields in Mira stars. First detection in χ Cygni
Context. So far, surface magnetic fields have never been detected on Mira stars. Only recently have the spectropolarimetric capabilities of measuring it via the Zeeman effect become available to us.
Atmospheric dynamics and the mass loss process in red supergiant stars
Context. Red supergiant stars represent a key phase in the evolution of massive stars. Recent radiative hydrodynamic simulations suggest that their atmospheres may be the location of large-scale
Envelope tomography of long-period variable stars II. Method
A tomographic method is described that makes it possible to follow the propagation of shock waves across the photosphere of long-period variable stars. The method relies on the correlation of the