2007/03/21 by A. D. Schwope, A. Staude, D. Koester +1 · 33 citations
Physics and Astronomy · #Accretion (finance) #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Emission spectrum #Flux (metallurgy) #Luminosity #Spectral energy distribution #Spectral line #Stellar classification #White dwarf #astro-ph
paper · pdf · doi:10.1051/0004-6361:20066928
published in Astronomy and Astrophysics 469(3), 1027-1031 (EDP Sciences) · A&A, in press
arxiv created 2007/03/21 · openalex publication_date 2007/03/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Archival X-ray observations of EF Eridani obtained in a low state revealed distinct X-ray detections at a luminosity 2 1029 erg s-1, three orders of magnitude below its high state value. The plasma temperature was found to be as low as keV, a factor 10 below the high state. The X-ray/UV/IR spectral energy distribution suggests faint residual accretion rather than coronal emission as being responsible for the low-state X-ray emission. EF Eri thus showed a clear transition from being shock-dominated in the high state to be cyclotron-dominated in the low state. From the optical/UV spectral energy distribution we re-determine the photospheric temperature of the white dwarf to ~10 000 K. Contrary to earlier claims, WD model atmospheres produce sufficient UV flux to reproduce the published GALEX flux and orbital modulation.