Gamma Aquilae - Tarazed

Magnitude 2.72 Tarazed is the second brightest star in the constellation Aquila, but has the designation γ Aql (fainter Alshain is β Aql). One of the few stars that does not have an Arabic-derived name, "Tarazed" comes from a Persian phrase meaning "the Beam of the Scale," which was originally applied to the star Altair and its two flanking stars, Tarazed and Alshain.

Properties

Tarazed is a class K3 bright giant, a fairly cool star (at 4100 K) that falls between the ordinary giants and supergiants. Its distance of 460 light years implies a luminosity of 2960 times the Sun's, and a radius of 110 times solar. At 0.5 AU across, if γ Aql were our Sun, it would extend halfway to the orbit of the Earth and appear 60 degrees across in our sky. It is so large that it can be detected as a disk with an angular diameter of 0.0075". This gives the same physical diameter as above, showing all these measures to be quite accurate.

Tarazed is a source of X-rays, and is a rare "hybrid" star that has characteristics of both luminous giants with cool winds, and less-luminous giants that have hot outer layers like the Sun's. Its luminosity and temperature suggest a mass about five times solar. Though only a little over 100 million years old, the star is probably already fusing helium into carbon in its core, and will ultimately become a white dwarf.

[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]