2019A&A...632A..28K


C.D.S. - SIMBAD4 rel 1.7 - 2021.01.24CET01:51:38

2019A&A...632A..28K - Astronomy and Astrophysics, volume 632A, 28-28 (2019/12-0)

Tomography of cool giant and supergiant star atmospheres. II. Signature of convection in the atmosphere of the red supergiant star µ Cep.

KRAVCHENKO K., CHIAVASSA A., VAN ECK S., JORISSEN A., MERLE T., FREYTAG B. and PLEZ B.

Abstract (from CDS):


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 distribution over the stellar disk and within different optical-depth slices. This method was applied to a series of high-resolution spectra of µ Cep, and these results are compared to those obtained from 3D radiative-hydrodynamics CO5BOLD simulations of red supergiants. Fluctuations in the velocity field are compared with photometric and spectroscopic variations, the latter were derived from the TiO band strength and serve, at least partly, as a proxy of the variations in effective temperature.
Results. The tomographic method reveals a phase shift between the velocity and spectroscopic and photometric variations. This phase shift results in a hysteresis loop in the temperature - velocity plane with a timescale of a few hundred days, which is similar to the photometric one. The similarity between the hysteresis loop timescale measured in µ Cep and the timescale of acoustic waves disturbing the convective pattern suggests that such waves play an important role in triggering the hysteresis loops.

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: atmospheres - stars: AGB and post-AGB - supergiants - line: formation - radiative transfer - techniques: spectroscopic

Simbad objects: 4

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Number of rows : 4

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1503 0
2 V* R CMi S* 07 08 42.6121867471 +10 01 26.464001661   9.65 7.25     SC4-7/10e 152 0
3 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 1019 0
4 * mu. Cep s*r 21 43 30.4610574 +58 46 48.160181 8.85 6.43 4.08 1.98 0.22 M2-Ia 626 1

    Equat.    Gal    SGal    Ecl

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2021.01.24-01:51:38

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