APOD: November 28, 1998 - A Lonely Neutron Star (original) (raw)

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

November 28, 1998

Explanation: How massive can a star get without imploding into a black hole? These limits are being tested by the discovery of a loneneutron star in space.Observations by the Hubble Space Telescope have been combined with previous observations by the X-ray ROSAT observatory and ultraviolet EUVEobservatory for the isolated star at the location of the arrow. Astronomers are able to directly infer the star's size from measurements of its unblended brightness, temperature, and an upper limit on the distance. Assuming that the object is a neutron star of typical mass, some previous theories of neutron star structure would have predicted an implosion that would havecreated a black hole. That this neutron stareven exists therefore allows a window to the extreme conditions that exist in the interiors of neutron stars.