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- Astrophysics (3)
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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
Hd 43246 And Hd 127208: Two Unusual F-G + B Binary Systems, Robert C. Dempsey, Bernard W. Bopp, Sidney B. Parsons, Francis C. Fekel
Hd 43246 And Hd 127208: Two Unusual F-G + B Binary Systems, Robert C. Dempsey, Bernard W. Bopp, Sidney B. Parsons, Francis C. Fekel
Information Systems and Engineering Management Research Publications
New optical spectroscopic observations along with ultraviolet IUE observations have been obtained for the two interacting F or G III + B V binaries: HD 43246 and HD 127208. Photometric observations indicate random changes superimposed on regular ellipsoidal light variations, the latter probably the result of tidal distortion of the giant primaries. Mass transfer and loss is apparent in inverted mass ratios derived from orbital analysis, strong wind features present in the spectra, and the presence of circumsystem shells. Regular and irregular changes in the spectral features are discussed in this context.
Hr 1362: A Test Case For Stellar Dynamo Theories, Klaus G. Strassmeier, Douglas S. Hall, William S. Barksdale, Anthony T. Jusick, Gregory W. Henry
Hr 1362: A Test Case For Stellar Dynamo Theories, Klaus G. Strassmeier, Douglas S. Hall, William S. Barksdale, Anthony T. Jusick, Gregory W. Henry
Information Systems and Engineering Management Research Publications
An analysis of 11 yr of photometry of HR 1362 = EK Eri has shown a well-established photometric period of 335 days. This confirms an earlier period determination of about 310 days from 3 yr of APT data and is consistent with a new v sin i determination of 2 + or - 2 km/s. Recent Ca II H and K observations show moderately strong H and K emission lines at a flux level of log F prime (K) of about 6.5 ergs sq m/s. If the photometric period is interpreted as the rotation period, this surface flux is more …
Evolution Of The Starspots In V478 Lyrae From 1980 To 1988, Douglas S. Hall, Gregory W. Henry, James R. Sowell
Evolution Of The Starspots In V478 Lyrae From 1980 To 1988, Douglas S. Hall, Gregory W. Henry, James R. Sowell
Information Systems and Engineering Management Research Publications
Differential UBV photometry of V478 Lyrae from 1980 to 1988 is given and analyzed as 22 separate light curves, each spanning an average of a dozen rotation cycles. It is shown that spots on V478 Lyr appear to have lifetimes on the order of several months to a year. The amplitude of the light loss produced by a spot can change by a factor of 2 within 20 days. In the only four determinate cases, a spot came into existence at one of the two conjunctions, that is, in the middle of the hemisphere facing (or opposing) the companion star. …
Chromospheric Ca Ii H And K And H Alpha Emission In Single And Binary Stars Of Spectra Types F6--M2, Klaus G. Strassmeier, Francis C. Fekel, Bernard W. Bopp, Robert C. Dempsey, Gregory W. Henry
Chromospheric Ca Ii H And K And H Alpha Emission In Single And Binary Stars Of Spectra Types F6--M2, Klaus G. Strassmeier, Francis C. Fekel, Bernard W. Bopp, Robert C. Dempsey, Gregory W. Henry
Information Systems and Engineering Management Research Publications
New observations of the Ca II H and K and H-epsilon region and/or the Balmer H-alpha line are presented for 100 mostly very active stars but also for weak or inactive stars with suspected activity. Correlations between chromospheric activity at Ca II H and K and H-alpha and effective surface temperature and rotation are identified, and several new stars with chromospheric Ca II H and K emission are discovered. No single activity-rotation relation can be derived for all luminosity classes, and there is clear evidence that evolved stars are generally more active than main-sequence stars of the same rotation period. …