[1] In 2014, it was discovered that the star HV 2112, located in the Small Magellanic Cloud (SMC), was a strong candidate,[2][3] though this view has since been refuted.
[6] If a neutron star and a white dwarf merge, this could form a Thorne–Żytkow object with the properties of an R Coronae Borealis variable.
[8][9] Because of the high temperature, unusual nuclear processes may take place as the envelope of the red giant falls onto the neutron star's surface.
[10] Observationally, a Thorne–Żytkow object may resemble a red supergiant,[2] or, if it is hot enough to blow off the hydrogen-rich surface layers, a nitrogen-rich Wolf–Rayet star (type WN8).
It is possible to detect pre-existing TŻOs with current LIGO detectors; the neutron star core would emit a continuous wave.
[2] However, this claim was challenged in a 2018 paper by Emma Beasor and collaborators,[4] who argued that there is no evidence for HV 2112 having any unusual abundance patterns beyond a possible enrichment of lithium and that its luminosity is too low.