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The white dwarf binary pathways survey – VIII. A post-common envelope binary with a massive white dwarf and an active G-type secondary star
Journal
Monthly Notices of the Royal Astronomical Society
Date Issued
2022-12-01
Author(s)
Hernandez, M. S.
Schreiber, M. R.
Parsons, S. G.
Gänsicke, B. T.
Toloza, O.
Zorotovic, M.
Raddi, R.
Rebassa-Mansergas, A.
Ren, J. J.
Abstract
The white dwarf binary pathways survey is dedicated to studying the origin and evolution of binaries containing a white dwarf
and an intermediate-mass secondary star of the spectral type A, F, G, or K (WD+AFGK). Here we present CPD-65 264, a new
post common envelope binary with an orbital period of 1.37 days that contains a massive white dwarf (0.86 ± 0.06 M ) and
an intermediate-mass (1.00 ± 0.05 M ) main-sequence secondary star. We characterized the secondary star and measured the
orbital period using high-resolution optical spectroscopy. The white dwarf parameters are determined from HST spectroscopy. In
addition, TESS observations revealed that up to 19 percent of the surface of the secondary is covered with starspots. Small period
changes found in the light curve indicate that the secondary is the second example of a G-type secondary star in a post common
envelope binary with latitudinal differential rotation. Given the relatively large mass of the white dwarf and the short orbital
period, future mass transfer will be dynamically and thermally stable and the system will evolve into a cataclysmic variable. The
formation of the system can be understood assuming common envelope evolution without contributions from energy sources
besides orbital energy. CPD-65 264 is the seventh post common envelope binaries with intermediate-mass secondaries that can
be understood assuming a small efficiency in the common envelope energy equation, in agreement with findings for post common
envelope binaries with M-dwarf or sub-stellar companions.
and an intermediate-mass secondary star of the spectral type A, F, G, or K (WD+AFGK). Here we present CPD-65 264, a new
post common envelope binary with an orbital period of 1.37 days that contains a massive white dwarf (0.86 ± 0.06 M ) and
an intermediate-mass (1.00 ± 0.05 M ) main-sequence secondary star. We characterized the secondary star and measured the
orbital period using high-resolution optical spectroscopy. The white dwarf parameters are determined from HST spectroscopy. In
addition, TESS observations revealed that up to 19 percent of the surface of the secondary is covered with starspots. Small period
changes found in the light curve indicate that the secondary is the second example of a G-type secondary star in a post common
envelope binary with latitudinal differential rotation. Given the relatively large mass of the white dwarf and the short orbital
period, future mass transfer will be dynamically and thermally stable and the system will evolve into a cataclysmic variable. The
formation of the system can be understood assuming common envelope evolution without contributions from energy sources
besides orbital energy. CPD-65 264 is the seventh post common envelope binaries with intermediate-mass secondaries that can
be understood assuming a small efficiency in the common envelope energy equation, in agreement with findings for post common
envelope binaries with M-dwarf or sub-stellar companions.
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