X-ray transient

An X-ray transient is a type of astronomical object that emits X-rays in a variable and often short-lived manner. These sources are typically associated with binary star systems where a compact object, such as a black hole or neutron star, is accreting material from a companion star. X-ray transients can exhibit outbursts or flares that can last from days to months, during which their X-ray emission increases significantly, often by several orders of magnitude.