Sadr (Gamma Cygni)

Gamma Cygni (Sadr)

Gamma Cyg and IC 1318. Image: Ed Szczepanski.

Sadr is the third brightest star in the constellation Cygnus and the center star of the Northern Cross. Sadr lies at the northern end of the Great Rift with a spectacular portion of the Milky Way as a backdrop. Its name comes from an Arabic phrase meaning "the hen's breast."


Unlike most supergiants, which are either fairly hot or quite cool and reddish, Sadr is yellow-white and in the mid-temperature range. It has left the main sequence and is now near a region of temperature and luminosity in which stars become unstable and pulsate.


visual magnitude 2.23
absolute magnitude -6.12
spectral type F8Ib
surface temperature 6,500 K
luminosity 65,000 Lsun
mass 12 Msun
distance 1,520 light-years
position RA 20h 22m 13.7s,
Dec +40° 15' 24"