Geminga joins the class

Article Abstract:

A pulsar has been found to be the elusive gamma-ray source that astrophysicists facetiously named Geminga after the constellation Gemini and the Italian expression for 'it is not there.' Scientists had detected the gamma-rays but had been unable to find the rays' X-ray and optical counterpart. Now two researchers, J.P. Halpern and S.S. Holt, have succeeded in making the identification; the object turned out to be a pulsar similar to the Crab and Vela pulsars. The finding of pulsations with a period of 0.237 seconds in X-rays was crucial to the identification.

Pulsars, Gamma Ray Observatory (Artificial satellite)

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Geminga: new period, old gamma-rays

Article Abstract:

The star Geminga, a gamma-ray source, has been positively identified with the Einstein X-ray source 1E0630+178. Analysis of observational data from the SAS-II, ROSAT, EGRET and COS-B satellites has confirmed that the two sources are one and the same. The observations suggest that Geminga is a magnetized, revolving, middle-aged neutron star, although it does not appear to be a radio pulsar. Another Einstein X-ray source, 1E1257.4-5209, may be another example of an isolated neutron star.

X-ray astronomy

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The proper motion of Geminga's optical counterpart

Article Abstract:

The proper motion of the optical counterpart, G", of the gamma ray pulsar Geminga has been measured at 0.17 arcsec per year. This rate was determined by comparing data from optical images of G" obtained in 1984, 1987 and 1992. These results would follow if G" were a neutron star at about the same distance as Geminga. Thus, they confirm that G" is the optical counterpart of Geminga.

Identification and classification, Pulsating stars

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