The outer atmosphere of the M-type supergiant alpha Orionis: KI 7699A emission

Abstract

Spatially-resolved high-resolution long-slit spectra of Betelgeuse's circumstellar shell are described for a spectral window centered on the 7699Åresonance line of neutral potassium. The K I emission from resonance fluorescent scattering of photospheric photons which is mapped out to 50 arcsec from the star is approximately spherically symmetric with a brightness decreasing as r^{-2.36 \pm 0.03}, where $r$ is the radial distance from the star. Our measurements together with the earlier theoretical interpretation by Rodgers & Glassgold suggest that the mass loss rate is about 2 . 10^{-6} solar mass/year. The K I emission is far from homogeneous: intensity inhomogeneities are seen down to the seeing limit of about 1 arcsec and the velocity resolution of about 2 km/s. There is clear evidence for a thin shell of 50 arcsec radius. This is identified with the weaker circumstellar absorption component known as S2. Estimates are made of the density of K atoms in this shell (approx. 6 . 10^{-5} cm^{-3}).

arXiv comment10 pages, 7 figures

References in corpus (1)

• Mid-Infrared Imaging of Alpha Orionis

Cited by in corpus (14)

• The mass-loss rates of red supergiants and the de Jager prescription
• Red supergiants as potential Type IIn supernova progenitors: Spatially resolved 4.6 micron CO emission around VY CMa and Betelgeuse
• Atmospheric dynamics and the mass loss process in red supergiant stars
• Spatially resolving the inhomogeneous structure of the dynamical atmosphere of Betelgeuse with VLTI/AMBER
• The Pristine Survey IV: Approaching the Galactic metallicity floor with the discovery of an ultra metal-poor star
• Evolutionary tracks for Betelgeuse
• Circumstellar effects on the Rb abundances in O-rich AGB stars
• TEXES Observations of M Supergiants: Dynamics and Thermodynamics of Wind Acceleration
• Spatially extended K I 7699 emission in the nebula of VY CMa: Kinematics and geometry
• Detailed Chemical Abundances of Four Stars in the Unusual Globular Cluster, Palomar 1
• NOEMA maps the CO $J=2-1$ environment of the red supergiant $\mu$ Cep
• CARMA CO(J = 2 - 1) Observations of the Circumstellar Envelope of Betelgeuse
• The Magnetised Bellows of Betelgeuse
• The effect of winds on atmospheric layers of red supergiants II. Modelling VLTI/GRAVITY and MATISSE observations of AH Sco, KW Sgr, V602 Car, CK Car and V460 Car