TY - JOUR
T1 - First image of the surface of a star with the Hubble Space Telescope
AU - Gilliland, Ronald L.
AU - Dupree, A. K.
N1 - Funding Information:
We thank Peter Edmonds, Steve Hulbert, Han Uitenbroek, and Dimitar Sasselov for discussion and assistance with analyses. Excellent support by the many members of STScI, particularly the FOC Group, in implementing these observations is gratefully acknowledged. This work was supported in part by STScI grant GO-5409.01-93A to the Space Telescope Science Institute and STScI grant GO-5409.02-93A to the Smithsonian Astrophysical Observatory.
PY - 1996
Y1 - 1996
N2 - A direct image of the surface of a star, Betelgeuse (=α Ori; M2 lab), has been obtained with the Faint Object Camera on the Hubble Space Telescope. Images in two ∼300 Å-wide bands centered at 2550 and 2800 Å cover ∼10 resolution elements on the stellar disk. The ultraviolet diameter of Betelgeuse of 125 ± 5 mas at 2500 Å (corresponding to 108 ± 4 mas, FWHM) is a factor of 2.2 larger than the optical diameter, thus indicating a substantially extended chromosphere in this supergiant. A single bright, unresolved area is present in the southwest quadrant of the disk (P.A. = 235°) in both images, with a peak amplitude of 1.3-1.8 as compared to the surrounding disk and a temperature differential in excess of 200 K. This feature may be the result of magnetic activity, atmospheric convection, or global pulsations and shock structures that heat the chromosphere. Spatially resolved spectroscopy of the Mg II λλ2795, 2802 doublet with the Goddard High Resolution Spectrograph suggests complicated dynamics, with outflowing material in the chromosphere indicated by the Mg II emission.
AB - A direct image of the surface of a star, Betelgeuse (=α Ori; M2 lab), has been obtained with the Faint Object Camera on the Hubble Space Telescope. Images in two ∼300 Å-wide bands centered at 2550 and 2800 Å cover ∼10 resolution elements on the stellar disk. The ultraviolet diameter of Betelgeuse of 125 ± 5 mas at 2500 Å (corresponding to 108 ± 4 mas, FWHM) is a factor of 2.2 larger than the optical diameter, thus indicating a substantially extended chromosphere in this supergiant. A single bright, unresolved area is present in the southwest quadrant of the disk (P.A. = 235°) in both images, with a peak amplitude of 1.3-1.8 as compared to the surrounding disk and a temperature differential in excess of 200 K. This feature may be the result of magnetic activity, atmospheric convection, or global pulsations and shock structures that heat the chromosphere. Spatially resolved spectroscopy of the Mg II λλ2795, 2802 doublet with the Goddard High Resolution Spectrograph suggests complicated dynamics, with outflowing material in the chromosphere indicated by the Mg II emission.
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U2 - 10.1086/310043
DO - 10.1086/310043
M3 - Article
AN - SCOPUS:0040423730
SN - 0004-637X
VL - 463
SP - L29-L32
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 PART II
ER -