GALEX and Optical Light Curves of EF Eridanus During a Low State: the Puzzling Source of UV Light

Abstract

Low state optical photometry of EF Eri during an extended low accretion state combined with GALEX near and far UV time-resolved photometry reveals a source of UV flux that is much larger than the underlying 9500K white dwarf, and that is highly modulated on the orbital period. The near UV and optical light curves can be modeled with a 20,000K spot but no spot model can explain both the large amplitude FUV variations and the SED. The limitations of limb darkening, cyclotron and magnetic white dwarf models in explaining the observations are discussed.

10 pages, 4 figures to be published in ApJ Letters

References in corpus (1)

• A 110 MG cyclotron harmonic in the optical spectrum of RX J1554.2+2721

Cited by in corpus (5)

• The nature of the close magnetic white dwarf + probable brown dwarf binary SDSS J121209.31+013627.7
• Cyclotron modeling phase-resolved infrared spectroscopy of polars I: EF Eridani
• XMM-Newton observations of EF Eridani: the textbook example of low-accretion rate polars
• The Mid-Infrared Spectrum of the Short Orbital Period Polar EF Eridani from the Spitzer Space Telescope
• GALEX, Optical and IR Light Curves of MQ Dra: UV Excesses at Low Accretion Rates