Gamma Capricorni - Nashira

Gamma Capricorni is the fourth brightest star in the constellation Capricornus. It has the traditional name Nashira, which comes from the Arabic for "bearer of good news". Because it is near the ecliptic, γ Cap can be occulted by the Moon, and (rarely) by planets.

Properties

γ Cap is a blue-white class A7 III giant star with a mean apparent magnitude of +3.69, approximately 139 light years from Earth. This allows a calculation of its luminosity, showing it to radiate 47 times more energy than the Sun. The combination of the star's 7950 K temperature and its luminosity imply a mass of 2.5 suns, and show that Nashira is most likely a nascent giant star, one that has stopped its fusing its internal hydrogen or is very close to doing so.

Nashira seems to be rotating slowly, only 30 km/sec at the equator. That is 15 times faster than the Sun's rotation speed, but small compared with the speeds more common to class A stars. Nashira is classified as a rotating α2 CVn-type variable star; its brightness varies by 0.03 magnitudes as the star turns. Its relatively slow rotation causes less atmospheric stirring, allowing a possible separation of elements. Indeed, Nashira seems to be classified as metallic-line star, though there has been no in-depth study of it.

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