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Full-Text Articles in Physical Sciences and Mathematics
Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli
Photospheric Temperature Measurements In Young Main Sequence Stars, Katia Biazzo, Antonio Frasca, Gregory W. Henry, S. Catalano, Ettore Marilli
Information Systems and Engineering Management Research Publications
As part of our program to study stellar photospheric and chromospheric activity, we have examined several young solar type stars with activity levels intermediate between the Sun and the very active RS CVn binaries. We have analysed contemporaneous spectroscopic data obtained at Catania Observatory (Serra La Nave station, Mt. Etna) and photometric data acquired in the Stromgren bands with an automatic photometric telescope (APT) at Fairborn Observatory (Arizona, USA). Surface inhomogeneities have been detected from the rotational modulation of stellar brightness as well as from the modulation of several photospheric line-depth ratios (LDRs). The presence of chromospheric plage-like regions has …
Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry
Why Do Some Spotted Stars Become Bluer As They Become Fainter?, Vidar Aarum-Ulvås, Gregory W. Henry
Information Systems and Engineering Management Research Publications
Chromospherically active, spotted stars generally become redder as well as fainter when large starspots rotate into view on the stellar disc. However, the RS CVn system UX Ari (a triple-lined system), becomes bluer as it gets fainter. One possible explanation is that hot, bright facular regions accompany the cool, dark photospheric spots of the active component. The bluer flux of the hotter, inactive component does not appear to be sufficient to explain the observed behaviour. We have begun a search for additional chromospherically active stars with a similar relation between colour and brightness, to investigate whether these relations can be …
Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston
Chromospherically Active Stars. Xxii. Hd 18955, A Massive K Dwarf Binary, Francis C. Fekel, Gregory W. Henry, Frank M. Alston
Information Systems and Engineering Management Research Publications
HD 18955 is a double-lined spectroscopic binary with a period of 43.3214 days and a high eccentricity of 0.761. The spectral types of the components are K0 V and K2-K3 V. The secondary is a typical early K dwarf, although its minimum mass is greater than canonical values. However, this larger mass is consistent with other early K dwarf, spectroscopic binary results. The primary is anomalous, being substantially underluminous for its radius and mass, which are equal to or slightly greater than solar values. A lack of lithium argues that the components are not pre-main-sequence stars. The large minimum masses …