The Secret XUV Lives of Cepheids: FUV-X-ray Observations of Polaris and beta Dor - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




The Secret XUV Lives of Cepheids: FUV-X-ray Observations of Polaris and beta Dor - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We report on the surprising recent discovery of strong FUV emissions in twobright, nearby Classical Cepheids from analyses of FUSE archival observationsand one of our own approved observations just prior to the failure of thesatellite. Polaris and beta Dor are currently the only two Cepheids to havebeen observed with FUSE, and beta Dor is the only one to have multiple spectra.Both Cepheids show strong C III 977A, 1176A and O VI 1032A, 1038Aemissions, indicative of 50,000-500,000 K plasma, well above the photospherictemperatures of the stars. More remarkably, beta Dor displays variability inthe FUV emission strengths which appears to be correlated to its 9.84-dpulsation period. This phenomenon has never before been observed in Cepheids.The FUV studies are presented along with our recent Chandra-XMM X-rayobservations of Polaris and beta Dor, in which X-ray detections were found forboth stars as well as for the prototype Classical Cepheid, delta Cep. FurtherX-ray observations have been proposed to unambiguously determine the origin andnature of the observed high energy emissions from the targets, possibly arisingfrom warm winds, shocks, or pulsationally induced magnetic activity. Theinitial results of this study are discussed.



Author: Scott G. Engle, Edward F. Guinan, Joseph DePasquale, Nancy Evans

Source: https://arxiv.org/







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