RXJ 0439 . 8 - 6809 : a double - degenerate supersoft X - ray source ? ?
نویسنده
چکیده
We present optical CCD photometry of the supersoft X-ray source RX J0439.8-6809. The absence of significant X-ray and optical variability (3σ peak-to-peak ∆V < 0.07) and the optical faintness (V ∼ 21.6) put severe constraints on a possible binary nature. Without rather unusual assumptions, a main-sequence donor star seems to be ruled out. All of the available information suggests that RX J0439 is either a doubledegenerate supersoft X-ray source with a predicted orbital period of a fewminutes or an extremely hot single pre-white dwarf. In either case, it is an extraordinarily rare and interesting object.
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