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Spectroscopic Evidence for Nonuniform Starspot Properties on II PegasiWe present spectroscopic evidence for Multiple Spot temperatures on the RS CVn star II Pegasi (HD 224085). We model the strengths of the 7055 and 8860 A TiO absorption bands in the spectrum of II Peg using weighted sums of inactive comparison spectra: a K star to represent the nonspotted photosphere and an M star to represent the spots. The best fit yields independent measurements of the starspot filling factor (f(sub s) and mean spot temperature (T(sub s)) averaged over the visible hemisphere of the star. During three-fourths of a rotation of II Peg in late 1996, we measure a constant f(sub s) approximately equals 55% +/- 5%. However, (T(sub s) varies from 3350 +/- 60 to 3550 +/- 70 K. We compute (T(sub s) for two simple models: (1) a star with two distinct spot temperatures, and (2) a star with different umbral/penumbral area ratios. The changing (T(sub s) correlates with emission strengths of H(alpha) and the Ca II infrared triplet in the sense that cooler (T(sub s) accompanies weaker emission. We explore possible implications of these results for the physical properties of the spots on II Peg and for stellar surface structure in general.
Document ID
19990017751
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
ONeal, Douglas
(Colorado Univ. Boulder, CO United States)
Saar, Steven H.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA United States)
Neff, James E.
(Charleston Coll. Charleston, SC United States)
Date Acquired
August 19, 2013
Publication Date
July 1, 1998
Publication Information
Publication: Astrophysical Journal
Publisher: American Astronomical Society
Volume: 501
Subject Category
Astronomy
Funding Number(s)
CONTRACT_GRANT: NAGw-2603
CONTRACT_GRANT: GO-06072.02-94A
CONTRACT_GRANT: NGT-51406
CONTRACT_GRANT: NSF AST-95-28563
CONTRACT_GRANT: NAG5-3040
CONTRACT_GRANT: GO-06676.01-95A
Distribution Limits
Public
Copyright
Other

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