The case and fate of HD 75767 – neutron star or supernova? |
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| Authors: | Klaus Fuhrmann Eike Guenther Brigitte König Jan Bernkopf |
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| Institution: | Isaac Newton Group of Telescopes, Apartado 321, E-38700 Santa Cruz de La Palma, Canary Islands, Spain;Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany;Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA;Universitäts-Sternwarte München, Scheinerstraße 1, D-81679 München, Germany |
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| Abstract: | We report the discovery of the nearby ( d = 24 pc) HD 75767 as an eight billion year old quadruple system consisting of a distant M dwarf pair, HD 75767 C–D, in orbit around the known short-period P = 10.25 d single-lined binary HD 75767 A–B, the primary of which is a solar-like G star. On the reasonable assumption of synchronous orbital rotation as well as rotational and orbital coplanarity for the inner pair, we get M B= 0.96 M⊙ for the unseen HD 75767 B, that is, the case of a massive white dwarf. Upon future evolution, mass transfer towards HD 75767 B will render the M A= 0.96 M⊙ G-type primary, now a turnoff star, to become a helium white dwarf of M A～ 0.33 M⊙ . Depending on the mass accretion rate, accretion efficiency and composition of the massive white dwarf, this in turn may result in a collapse of HD 75767 B with the formation of a millisecond pulsar, i.e. the creation of a low-mass binary pulsar (LMBP), or, instead, a Type Ia supernova explosion and the complete disruption of HD 75767 B. Irrespective of which scenario applies, we point to the importance of the distant M dwarfs as the likely agents for the formation of the inner, short-period HD 75767 A–B pair, and hence a path that particularly avoids preceding phases of common envelope evolution. |
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| Keywords: | binaries: close stars: evolution stars: individual: HD 75767 pulsars: general supernovae: general white dwarfs |
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