1996A&A...307L..49V

We have identified RX J0439.X-6809 with a very blue B=21.5 object. There is no evidence for x-ray or optical variability. The optical spectrum does not show any absorption or emission features. The very blue optical spectrum suggests that the optical flux is the Rayleigh-Jeans tail of the soft X-ray component. The spectral parameters are consistent with a location in the Large Magellanic Cloud. RX J0439 may be an accreting binary in which a low-mass white dwarf is recurrently burning accreted matter with a very long X-ray on-time. Alternatively, RX J0439 may be a ∼1M_☉ post-AGB star, which may have re-entered the high-luminosity phase due to a late helium shell flash.