Astronomers have identified a star system about 300 light-years away where a small star is slowly consuming a brown dwarf companion. The system, designated ZTF J0440+2325, was described in a study published October 5 in Nature Astronomy by a team led by MIT. Unlike the rapid engulfment seen in other systems, this star is steadily drawing material from its companion.
The discovery began with an unusual triangular light curve spotted in data from the Zwicky Transient Facility. The signal did not match known patterns such as supernovae or black widow binaries. Because the two objects have relatively similar low masses, they orbit each other gently rather than producing the dramatic whipping motion seen in systems containing a neutron star.
The brown dwarf orbits its star every 87 minutes. The slow transfer of material could continue for hundreds of thousands to billions of years, offering a new picture of how stars and low-mass companions interact. The researchers note this is the first observed example of a low-mass star steadily feeding on another low-mass object.