2 October 2016 | The Hen’s Chest


Image credit: André van der Hoeven | Click to enlarge


Gamma Cygni, also named Sadr, is a star in the northern constellation of Cygnus, forming the intersection of an asterism of five stars called the Northern Cross.

It bore the traditional name Sadr (also spelled Sadir or Sador), derived from the Arabic for “chest”, the same word which gave rise to the star Schedar (Alpha Cassiopeiae). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name Sadr for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Sadr al Dedjadjet, which was translated into Latin as Pectus Gallinǣ, meaning the hen’s chest.

Compared to the Sun this is an enormous star, with 12 times the Sun’s mass and about 150 times the Sun’s radius. It is emitting over 33,000 times as much energy as the Sun, at an effective temperature of 6,100 K in its outer envelope. This temperature is what gives the star the characteristic yellow-white hue of an F-type star. Massive stars such as this consume their nuclear fuel much more rapidly than the Sun, so the estimated age of this star is only about 12 million years old.


Tomorrow’s EAPOD: A Room with a View

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