Mar 15 – 20, 2020
Europe/Berlin timezone

Ultra-compact Double Degenerate Binaries

Mar 19, 2020, 3:35 PM



Thomas Prince (Calech)


Double degenerate white dwarf binaries result from episodes of common envelope evolution and evolve to short orbital period through gravitational wave emission. When the lighter of the two white dwarfs fills its Roche Lobe, mass transfer is initiated onto the heavier white dwarf, resulting in X-ray emission. At sufficiently close separation, the transferred mass does not form an accretion disk, but rather the ballistic stream impacts the surface of the white dwarf, forming a "direct impact accretor". We will describe an eclipsing double degenerate binary with an orbital period of 6.9 minutes recently discovered by the Zwicky Transient Facility, and discuss the possibility that it exhibits low-level direct impact mass transfer, as well as our attempts to detect X-ray emission from the system. We will also discuss possibilities for detection of direct impact accretors with SRG.

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