Theta Andromedae is a binary star [11] system in the northern constellation of Andromeda. Theta Andromedae, Latinized from θ Andromedae, is its Bayer designation. It is located at a distance of approximately 173 light-years (53 parsecs) 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]
In Chinese, 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]
Theta Andromedae is a binary star [11] system in the northern constellation of Andromeda. Theta Andromedae, Latinized from θ Andromedae, is its Bayer designation. It is located at a distance of approximately 173 light-years (53 parsecs) 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]
In Chinese, 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]