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Starspots found on the ellipsoidal variable V350 lacertae = HR 8575It has been a puzzle why this chromospherically active, strong-dynamo K2 IV-III star is not known to have the large starspots characteristic of other such stars. Published individual radial velocities, which had never been analyzed, are used to derive an orbital solution. Combined with the one older existing orbital solution, this yields an improved orbital ephemeris: time of conjunction (K star behind) = JD 2445255.47 +/- 0.11 days and period = 17.75346 +/- 0.00016 days. All available photoelectric photometry, from 1970.9 to 1992.5, is collected A cos 2 theta fit of the ellipticity effect yields JD 2445255.60 +/- 0.06 days for a time of conjunction, 17.7523 +/- 0.0005 days for the period, and 0.084 mins for the peak-to-peak amplitude in V. With the ellipticity effect removed, the light curve does show measurable starspot variability in 15 of 16 data groups, the starspot wave amplitudes ranging between 0.03 mins and 0.08 mins. Ten starspots are identified and their rotation periods determined, the mean being 17.70 +/- 0.03 days (confirming synchronous rotation) and the range being Delta P/P = 0.017 +/- 0.006 (indicating differential rotation). There is a slow variation in mean brightness, almost 0.1 min in range and at least 2 decades in length.
Document ID
19950061836
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Crews, Lionel J.
(Vanerbilt University Nashville, TN, United States)
Hall, Douglas S.
(Vanerbilt University Nashville, TN, United States)
Henry, Gregory W.
(Tennessee State University Nashville, TN, United States)
Lines, Richard D.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Lines, Helen C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Fried, Robert E.
(Braeside Observatory, Flagstaff, AZ United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1995
Publication Information
Publication: Astronomical Journal
Volume: 109
Issue: 3
ISSN: 0004-6256
Subject Category
Astronomy
Accession Number
95A93435
Funding Number(s)
CONTRACT_GRANT: NAG8-1014
CONTRACT_GRANT: NSF HRD-91-04484
Distribution Limits
Public
Copyright
Other

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