Smithsonian Astrophysical Observatory

Science Updates


The binary star system Her X-1 consists of a 1.5 solar-mass neutron star – the super-dense, collapsed remnant of a massive star – in orbit around the 2.2 solar-mass star, HZ Herculis.


One of the largest structures in the Milky Way galaxy, the North Polar Spur, was discovered at radio and X-ray wavelengths. The Spur is a giant ridge of bright emission that rises roughly perpendicularly out of the plane of the galaxy starting roughly in the constellation of Sagittarius and then curves upward, stretching across the sky for over thirty degrees (the size of sixty full-moons) where it appears to join other bright filamentary features.

The Smithsonian Astrophysical Observatory (SAO) is a "research institute" of the Smithsonian Institution. It is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). Because these research activities share Harvard and Smithsonian staff and resources, the links at this website will take you to information posted on the "CfA" pages.