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Full-Text Articles in Physical Sciences and Mathematics
Chromospherically Active Stars. Xv. Hd 8357=Ar Piscium, An Extremely Active Rs Cvn System, Francis C. Fekel
Chromospherically Active Stars. Xv. Hd 8357=Ar Piscium, An Extremely Active Rs Cvn System, Francis C. Fekel
Information Systems and Engineering Management Research Publications
One of the first x-ray sources optically identified as a chromospherically active star, HD 8357=AR Piscium, is a double-lined binary consisting of a K1 IV primary and G7 V secondary. Careful examination of the Ca II H and K lines indicates that only the primary is active, having strong Ca II H and K, Hɛ, and Hα emission. The system has an orbital period of 14.3023 days and an eccentricity of 0.185. Such an eccentricity is not particularly unusual for chromospherically active stars with periods between 10 and 20 days. An assumed mass of 0.92Msun for the secondary results in …
Flare Energetics: Analysis Of A Large Flare On Yz Canis Minoris Observed Simultaneously In The Ultraviolet, Optical And Radio., G. H. J. Van Den Oord, John G. Doyle, M. Rodono, D. E. Gary, Gregory W. Henry, Patrick B. Byrne, Jeffrey L. Linsky
Flare Energetics: Analysis Of A Large Flare On Yz Canis Minoris Observed Simultaneously In The Ultraviolet, Optical And Radio., G. H. J. Van Den Oord, John G. Doyle, M. Rodono, D. E. Gary, Gregory W. Henry, Patrick B. Byrne, Jeffrey L. Linsky
Information Systems and Engineering Management Research Publications
The results of coordinated observations of the dMe star YZ CMi at optical, UV and radio wavelengths during 3-7 February 1983 are presented. YZ CMi showed repeated optical flaring with the largest flare having a magnitude of 3.8 in the U-band. This flare coincided with an IUE exposure which permits a comparison of the emission measure curves of YZ CMi in its flaring and quiescent state. During the flare a downward shift of the transition zone is observed while the radiative losses in the range 10^4^-10^7^K strongly increase. The optical flare is accompanied with a radio flare at 6cm, while …
Random Spots On Chromospherically Active Stars, Joel A. Eaton, Gregory W. Henry, Francis C. Fekel
Random Spots On Chromospherically Active Stars, Joel A. Eaton, Gregory W. Henry, Francis C. Fekel
Information Systems and Engineering Management Research Publications
We have investigated the effect of large numbers of moderately sized spots placed randomly on a differentially rotating star as the explanation of the rotational light curves of magnetically active cool stars. This hypothesis produces light variation very similar to observed light curves of RS CVn binaries, provided there are of order 10-40 spots at any time and provided individual spots have a finite lifetime.
Hde 233517: Lithium And Excess Infrared Emission In Giant Stars, Francis C. Fekel, Richard A. Webb, Russel J. White, Benjamin Zuckerman
Hde 233517: Lithium And Excess Infrared Emission In Giant Stars, Francis C. Fekel, Richard A. Webb, Russel J. White, Benjamin Zuckerman
Information Systems and Engineering Management Research Publications
Recent studies have identified a small class of moderately rapidly rotating, chromospherically active, single giants, some of which are lithium rich. We present evidence suggesting the peculiar K-type star HDE 233517 is one such object. Previously, HDE 233517 has been suggested to be a young star, consistent with its large far-infrared excess and our log ε(Li) ~ 3.3. However, our high-resolution spectroscopic observations show it is likely a single, post-main-sequence K2 giant with v sin i = 15 km s-1 and modest Ca II H and K emission. The giant status of HDE 233517 is determined directly from luminosity-sensitive line …
A Search For Optical Flares In Chromospherically Active Stars, Gregory W. Henry, M. S. Newsom
A Search For Optical Flares In Chromospherically Active Stars, Gregory W. Henry, M. S. Newsom
Information Systems and Engineering Management Research Publications
We have surveyed four years of archival UBV photometry of 69 chromospherically active stars obtained with the Phoenix-10 automatic photoelectric telescope in search of optical flares on these stars. We demonstrate taht, while flares can be detected in these data, the number of events observed on evolved stars remains very small. Flares were found only on UX Arietis, II Pegasi, and AR Piscium.
Hd 12545, A Study In Spottedness, Melissa Hampton, Gregory W. Henry, Joel A. Eaton, Richard A. Nolthenius, Douglas S. Hall
Hd 12545, A Study In Spottedness, Melissa Hampton, Gregory W. Henry, Joel A. Eaton, Richard A. Nolthenius, Douglas S. Hall
Information Systems and Engineering Management Research Publications
We have solved two sets of light curves of HD 12545 at its epoch of extreme spottedness in 1990-91, one of which coincides with an independent set analyzed recently by Strassmeier and Olah. Even for the huge amplitudes observed, these light-curve solutions did not give reliable determinations of several important spot properties. Specifically, we find that we could obtain acceptable solutions for a wide range of inclination; that spot temperature depends on inclination assumed, falling in the range Delta-T = Tstar - Tspot = 650-1200 K for inclinations of 70-30 deg; that spot latitudes derived from the light curves are …