Delta Cygni, Latinized from ? Cygni, is the third-magnitude star in the constellation Cygnus. It will be the "North Star" for at least four centuries around 11,250.
This star belonged to the Arabic asterism al-Faw?ris (???????), meaning "the Riders" in indigenous Arabic, together with ?, ?, and ? Cyg, the transverse of the Northern Cross.
In Chinese, ?? (Ti?n J?n), meaning Celestial Ford, refers to an asterism consisting of ? Cygni, ? Cygni, 30 Cygni, ? Cygni, ? Cygni, ? Cygni, ? Cygni, ? Cygni and ? Cygni. Consequently, ? Cygni itself is known as ??? (Ti?n J?n èr, English: the Second Star of Celestial Ford.)
Video Delta Cygni
Features
Delta Cygni is a triple star; the system lies at a distance of about 170 light years and consists of two stars quite close together and one much farther out. This sort of common configuration lends stability.
The bright naked-eye star is a blue-white giant of spectral class B9, with a temperature of 10,500 K. It is nearing the end of its main-sequence life stage with a luminosity 155 times that of the Sun, a radius of 5.13 solar radii, and a mass approximately 2.93 solar masses. Like many hot stars, it spins rapidly, at least 135 kilometers per second at the equator, about 60 times that of the Sun. Its close companion is a yellow-white class F of the sixth magnitude (6.33) with a luminosity about 6 times that of the sun, and a mass about 1.5 times that of the sun. The much more distant third companion is an orange (class K) twelfth magnitude star, being only 38% as luminous as the sun, and only 70% as massive as the sun. As seen from Earth, the entire triple star system of Delta Cygni shines at a combined apparent magnitude of 2.86.
Maps Delta Cygni
'North star'
It is one of eight bright stars in the northern hemisphere that lay claim to the position of "North Star" over the course of Earth's 26,000-year precession cycle.
The other seven stars are
- Tau Herculis (of Hercules),
- Vega (of Lyra),
- Alpha Cephei (of Cepheus),
- Gamma Cephei (of Cepheus),
- Polaris (of Ursa Minor),
- Kappa Draconis (of Draco), and
- Alpha Draconis (of Draco).
See also
- Traditional Chinese star names in Cygnus
References
External links
- Marshall "Roc" Burns, My Nickname: The Mythological Roc - TheRoc.net
- James B. "Jim" Kaler, DELTA CYG (Delta Cygni) - STARS
- Alan M. MacRobert, Understanding Celestial Coordinates - Sky & Telescope
- Richard Powell, The Brightest Stars - An Atlas of The Universe
Source of article : Wikipedia
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