A Chinese-led satellite mission has detected a mysterious, transient celestial object in a discovery scientists say could represent a previously unknown category of cosmic phenomena.

Known as EP240408a, the object was first spotted in April by China's Einstein Probe satellite after it experienced a massive X-ray outburst. During the event, the object grew 300 times brighter but faded within seconds and disappeared roughly 10 days later.

The Einstein Probe, developed by the Chinese Academy of Sciences, is designed to monitor transient and eruptive celestial bodies. The mission's first formal study on the object was published Wednesday in the Science China Physics, Mechanics & Astronomy journal.

"The characteristics of this object don't fit any known models, suggesting it may belong to an entirely new class of transient celestial phenomena," said Yuan Weimin, chief scientist of the EP program at the National Astronomical Observatories of the CAS.