2010/05/13 by Paula Szkody, Anjum Mukadam, Anjum S. Mukadam +19
Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Flux (metallurgy) #Hubble space telescope #Optics #Orbit (dynamics) #Physics #Spectral line #Stars #Stellar, planetary, and galactic studies #Ultraviolet #Wavelength #White dwarf #Wide Field Camera 3 #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/716/2/1531
32 pages including 16 figures and 2 tables, accepted in ApJ
arxiv created 2010/05/13 · openalex publication_date 2010/06/03 · arxiv updated 2015/05/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Time-resolved spectra throughout the orbit of EF Eri during its low accretion state were obtained with the solar blind channel on the Advanced Camera for Surveys on board the Hubble Space Telescope . The overall spectral distribution exhibits peaks at 1500 and 1700 Å, while the UV light curves display a quasi-sinusoidal modulation over the binary orbit. Models of white dwarfs (WDs) with a hot spot and cyclotron emission were attempted to fit the spectral variations throughout the orbit. A non-magnetic WD with a temperature of ∼10,000 K and a hot spot with a central temperature of 15,000 K generally match the broad absorptions at 1400 and 1600 Å with those expected for the quasi-molecular H features H 2 and H + 2 . However, the flux in the core of the Lyα absorption does not go to zero, implying an additional component, and the flux variations throughout the orbit are not well matched at long wavelengths. Alternatively, a 9500 K WD with a 100 MG cyclotron component can fit the lowest (phase 0.0) fluxes, but the highest fluxes (phase 0.5) require an additional source of magnetic field or temperature. The 100 MG field required for the UV fit is much higher than that which fits the optical/IR wavelengths, which would support previous suggestions of a complex field structure in polars.