Discovery of a Thorne–Żytkow object candidate in the Small Magellanic Cloud

• DOI: 10.1093/mnrasl/slu080
• Publication Date: 2014-07-09T05:05:37Z
• Authors: Emily M. Levesque; Philip Massey; Anna N. Żytkow; Nidia Morrell
• Keywords: Astrophysics - Solar and Stellar Astrophysics; 13. Climate action; 0103 physical sciences; FOS: Physical sciences; 01 natural sciences; Solar and Stellar Astrophysics (astro-ph.SR)

Abstract Thorne–Żytkow objects (TŻOs) are a theoretical class of star in which a compact neutron star is surrounded by a large, diffuse envelope. Supergiant TŻOs are predicted to be almost identical in appearance to red supergiants (RSGs). The best features that can be used at present to distinguish TŻOs from the general RSG population are the unusually strong heavy-element and Li lines present in their spectra, products of the star's fully convective envelope linking the photosphere with the extraordinarily hot burning region in the vicinity of the neutron star core. Here, we present our discovery of a TŻO candidate in the Small Magellanic Cloud. It is the first star to display the distinctive chemical profile of anomalous element enhancements thought to be unique to TŻOs. The positive detection of a TŻO will provide the first direct evidence for a completely new model of stellar interiors, a theoretically predicted fate for massive binary systems, and never-seen-before nucleosynthesis processes that would offer a new channel for Li and heavy-element production in our Universe.