Institute of Astronomy

Thorne-Zytkow Objects

SpeakerTalk DateTalk Series
Christopher Tout27 July 2016Binary Stars Talks


A Thorne-Zytkow object has the structure of a red giant but with the electron degenerate core replaced by a neutron star. TZOs are powered by accretion on to the neutron degenerate core and this drives a convective envelope, the base of which is hot enough for nuclear burning when the envelope is massive. It is unclear whether this leads to a long-lived stable structure but existing models suggest that nuclear energy generation can dominate the accretion luminosity and we should expect rapid proton capture processes, with distinctive nucleosynthetic signatures, to be important. Recently a very bright red star HV2112, was identified as a possible candidate. The most likely formation mechanism for a TZO is the merging of a neutron star with the core of a giant during common envelope evolution. We discuss the likelihood that HV2112 is actually a TZO rather than the most likely alternative of a super-AGB star which would not have required a binary star progenitor.