TMTS J0526+5934


TMTS J0526+5934 is an ultracompact binary star system located approximately 2,760 light-years away in the constellation Camelopardalis. It was initially identified in 2019 by the Zwicky Transient Facility as an extremely low-mass white dwarf candidate, with further observations refining its classification.

Discovery

Discovered by ZTF, it was further studied by the Tsinghua University–Ma Huateng Telescopes for Survey, leading to its TMTS designation.

Characteristics

It consists of a hot subdwarf B star and a carbon-oxygen white dwarf companion, forming a detached double white dwarf binary, the fifth object with ultra-short period. It holds the record for the shortest known orbital period of a detached single-degenerate binary at. The subdwarf B star has a estimated radius of, representing possibly the smallest non-degenerate star known.

Evolution and Future

TMTS J0526+5934 is expected to merge due to gravitational wave emission in about 1.8–3 million years. The merger could result in a massive white dwarf of roughly solar mass, a helium-rich star, or potentially a Type Ia supernova. Its strong gravitational wave signal makes it a promising verification binary for the ESA's Laser Interferometer Space Antenna mission.