Geminga

Geminga is a neutron star believed to be the remnant of a supernova that occurred approximately 300,000 years ago. It is located in the constellation Gemini, about 815 light-years from Earth. What makes Geminga unique is that it is a powerful source of gamma rays but is relatively faint at other wavelengths, especially in the visible spectrum.

The name "Geminga" is a combination of "Gemini" and "gamma-ray source," reflecting its location and primary mode of detection. It was initially identified as a bright, unidentified gamma-ray source by the SAS-2 satellite in the early 1970s. For many years, its nature remained a mystery due to its unusual properties and faintness in other wavelengths.

In the 1990s, the ROSAT X-ray observatory detected pulsations from Geminga, revealing its true nature as a neutron star. It is now understood that Geminga emits powerful beams of radiation from its magnetic poles, which sweep across space as the neutron star rotates. These beams are responsible for the observed gamma-ray emissions.

Geminga's relative faintness in the visible spectrum is thought to be due to its age and the properties of the interstellar medium between Earth and the neutron star, which absorbs much of the lower-energy radiation. Its discovery and subsequent study have contributed significantly to our understanding of neutron stars, supernova remnants, and the generation of gamma rays in the universe.