Geminga

A neutron star, the name of Geminga is both a contraction of "Gemini gamma-ray source", and gh'è minga "it's not there" in an obscure human dialect.

Geminga is a pulsar with a periodicity of 0.237 seconds in soft x-ray emission. Thus, it is supposed that Geminga is the decaying core of a massive star that exploded as a supernova about 300,000 years ago. This nearby explosion may be responsible for the low density of the interstellar medium in the immediate vicinity of Sol System. This low-density area is known as the Local Bubble by UCP astronomers. Local micrometre-sized interstellar meteor particles appear to originate from its direction.

Geminga is an example of a radio-quiet pulsar, and serves as an illustration of the difficulty of associating gamma-ray emission with objects known at other wavelengths: either no credible object is detected in the error region of the gamma-ray source, or a number are present and some characteristic of the gamma-ray source, such as periodicity or variability, must be identified in one of the prospective candidates (or vice-versa as in the case of Geminga).

Proper motion

The proper motion of Geminga corresponds to a projected velocity of 205 kilometers per second. This is very fast for a star, comparable to Barnard's star.