Theta Andromedae is a binary star[11] system in the northern constellationofAndromeda. Theta Andromedae, Latinized from θ Andromedae, is its Bayer designation. It is located at a distance of approximately 173 light-years (53parsecs) from the Sun,[1] and has an apparent visual magnitude of 4.6.[2] On the Bortle Dark-Sky Scale, this makes it visible to the naked eye from outside urban regions. Based on its motion through space, this system appears to be a member of the Sirius supercluster.[12]
The brighter component is a white hued A-type main-sequence star with a stellar classification of A2 V.[4] It is one of the least photometrically variable stars known.[5] The star shows a high rate of rotation with a projected rotational velocity of 102 km/s.[3] It has an estimated 2.8[3] times the mass of the Sun and is radiating 113[7] times the Sun's luminosity from its photosphere at an effective temperature of 8,960 K.[9] The relatively high chemical abundances of iron and heavier elements suggests it may be a fast rotating Am star.[5]
A stellar companion was detected in 1986 and reported in 1989.[13] This fainter companion is separated from Theta Andromedae by 0.06 arcseconds.[11] The secondary appears to be a massive, possibly A-type, star orbiting at a distance of around one astronomical unit with a period of 2.83 years and a large orbital eccentricity (ovalness) of 0.95.[8]
InChinese, 天廄 (Tiān Jiù), meaning Celestial Stable, refers to an asterism consisting of θ Andromedae, ρ Andromedae and σ Andromedae. Consequently, the Chinese name for θ Andromedae itself is known as 天廄一 (Tiān Jiù yī, English: the First Star of Celestial Stable.)[14]
|
| |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||
| Stars |
| ||||||||||||
| |||||||||||||
| Star clusters |
| ||||||||||||
| Nebulae |
| ||||||||||||
| Galaxies |
| ||||||||||||
| |||||||||||||
| |||||||||||||
