X-Shooting EF Eridani: further evidence for a massive white dwarf and a sub-stellar secondary

Abstract

High resolution spectral observations of the polar EF Eridani obtained in a low state with X-Shooter revealed narrow emission lines from the irradiated secondary. The lines were most prominent in the near-IR Ca2-triplet, the more intensive Halpha line had additional emission likely originating from an accretion stream. The lines with a radial velocity amplitude, K2' = 385 +- 4 kmps, serve as tracer of the otherwise unseen companion. The mass function implies a massive white dwarf with Mwd > 0.65 Msun at 3sigma confidence, and a short distance to the binary, d ~ 111 pc (<145pc at 3sigma confidence). The spectral energy distribution from the UV to the IR together with the high mass ratio gives further strong evidence of EF Eri being a post period-minimum object with M2 < 0.06 Msun

Astron, Astrophys., in press

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Cited by in corpus (10)

• X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope
• Magnetic White Dwarfs
• The evolutionary state of short period magnetic white dwarf binaries
• Herschel Observations of Cataclysmic Variables
• Signs of accretion in the white dwarf + brown dwarf binary NLTT5306
• X-ray orbital modulation of a white dwarf accreting from an L dwarf: The system SDSS J121209.31+013627.7
• New X-ray detections of magnetic period-bounce cataclysmic variables from XMM-Newton and SRG/eROSITA
• Neglected X-ray discovered polars: II: The peculiar eclipsing binary HY Eridani
• Cataclysmic variables around the period-bounce: An eROSITA-enhanced multi-wavelength catalog
• X-ray and ultraviolet observations of the eclipsing cataclysmic variables OV Bootis and SDSS J103533.02+055158.3 with degenerate donors