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HST imaging of Betelgeuse

Published online by Cambridge University Press:  25 May 2016

Ronald L. Gilliland
Affiliation:
Space Telescope Science Institute 3700 San Martin Drive, Baltimore, MD 21218, USA
Andrea K. Dupree
Affiliation:
Smithsonian Astrophysical Observatory 60 Garden Street, Cambridge, MA 02138, USA

Extract

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We have obtained the first direct image of the surface of a star with HST in March 1995. Our near-ultraviolet images of the M2 Iab supergiant-star Betelgeuse (Alpha Orionis) taken with the COSTAR-corrected Faint Object Camera show about 10 resolution elements over the stellar disk. With direct resolution of Betelgeuse the following discoveries resulted: 1) The apparent size of the disk in the UV (≃ λ 2550) is larger by a factor of ≃2.1 than in the optical, demonstrating the extent of the supergiant atmosphere. 2) An unresolved hot spot (higher temperature than the disk by a few thousand degrees) dominates the spatial structure of the atmosphere. 3) The atmosphere at 2550 å extends to 125 milliarcsec (FWHM 108 mas) with a limb-darkening coefficient of about 1.0.

Type
Session II: “Direct Mapping: The Last Frontier”
Copyright
Copyright © Kluwer 1996 

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