A micronova is a type of thermonuclear explosion on the surface of a white dwarf much smaller than the strength of a nova; being about 1×1039 ergs (1.0×10−12 foe; 1.0×1032 J) in strength, about a millionth that of a typical nova. It was first described in April 2022.
A team at European Southern Observatory announced on 20 April 2022 that they identified three micronovae using data from the Transiting Exoplanet Survey Satellite (TESS).
The phenomenon had previously been reported for V2487 Ophiuchi, with the interpretation in the prior work being that the flaring comes from extreme stellar coronal activity. The existing data are not sufficient to distinguish clearly between the two mechanisms.