NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Evolution of starspots in the long-period RS CVN binary V1817 Cygni = HR 7428Photometry between 1982 and 1989, published and unpublished, is analyzed. The ellipticity effect produces variability with a full amplitude of 0.033 m in V. A recent time of light minimum (JD 2445988.0 + or - 0.3 d) combined with an old spectroscopic time of conjunction from the 1920's yields a much improved orbital period (108.854 + or - 0.003). Removal of the ellipticity effect reveals starspot variability. Four different spots were observed at various times, two of them present simultaneously in the light curve during 1985. Mean spot lifetimes were around 2 years and the largest amplitude attributed to starspots was 0.04 m in V during 1986. Derived rotation periods for two spots were 5.3 + or - 1.2 percent slower than synchronous and 3.0 + or - 0.4 percent faster. The differential rotation coefficient for the K2 giant is k = 0.25 + or - 0.04, compared to k = 0.186 for the sun. V1817 Cygni has the longest orbital period of any binary known to execute synchronous rotation.
Document ID
19910033127
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hall, Douglas S.
(Tennessee State University Nashville, United States)
Gessner, Susan E.
(Dyer Observatory Nashville, TN, United States)
Lines, Helen C.
(Tennessee State Univ. Nashville, TN, United States)
Lines, Richard D.
(Tennessee State Univ. Nashville, TN, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1990
Publication Information
Publication: Astronomical Journal
Volume: 100
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
91A17750
Funding Number(s)
CONTRACT_GRANT: NAG8-111
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available