A celestial object that is a very strong but transient emitter of X-rays, typically a binary system with either a neutron star or a black hole as the receptor (rather than a white dwarf as in an ordinary nova).
Origin
1960s; earliest use found in Science News.
Definition of X-ray nova in US English:
X-ray nova
noun
Astronomy
A celestial object that is a very strong but transient emitter of X-rays, typically a binary system with either a neutron star or a black hole as the receptor (rather than a white dwarf as in an ordinary nova).