NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Survey of the BY Draconis syndrome among dMe starsResults are reported for a BVr photometric survey of 22 dK, dKe, dM, and dMe stars conducted to search for slow quasi-sinusoidal fluctuations in V (the BY Draconis syndrome). The (B-V) and (V-r) color indices are determined in an attempt to detect wavelength-dependent color changes produced by starspots and to infer starspot temperatures. It is found that nine of the stars exhibit variations in V of the order of 0.05 to 0.10 magnitude on a time scale of days or weeks, that at least three more display changes in mean light level over a period of years, that the stars generally tend to become redder at minimum light, and that some of the stars show no detectable color changes over their photometric cycle. The color data are taken to suggest a probable temperature difference of about 200 to 500 K between the stellar photospheres and starspots if the V variations are attributed to dark spots. It is concluded that the BY Draconis syndrome is clearly a very common occurrence among dMe stars.
Document ID
19780029431
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bopp, B. W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Espenak, F.
(NASA Goddard Space Flight Center Greenbelt, Md., United States)
Date Acquired
August 9, 2013
Publication Date
November 1, 1977
Publication Information
Publication: Astronomical Journal
Volume: 82
Subject Category
Astronomy
Accession Number
78A13340
Distribution Limits
Public
Copyright
Other

Available Downloads

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