Delta Geminorum
 Location of δ Geminorum (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Gemini |
| Right ascension | 07h 20m 07.37978s[1] |
| Declination | +21° 58′ 56.3377″[1] |
| Apparent magnitude (V) | +3.53[2] |
| Characteristics | |
| Spectral type | F0 IV[3] |
| U−B color index | +0.04[2] |
| B−V color index | +0.34[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.1[4] km/s |
| Proper motion (μ) | RA: –15.13[1] mas/yr Dec.: –9.79[1] mas/yr |
| Parallax (π) | 53.94 ± 0.66[1] mas |
| Distance | 60.5 ± 0.7 ly (18.5 ± 0.2 pc) |
| Details | |
| Mass | 1.57[5] M☉ |
| Temperature | 6,900[6] K |
| Metallicity [Fe/H] | –0.26[6] dex |
| Rotational velocity (v sin i) | 129.7[7] km/s |
| Age | 1.6[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Delta Geminorum (δ Gem, δ Geminorum) is a star in the constellation Gemini. It has the traditional name Wasat, which comes from the Arabic word for "middle".[8][9]
It has an apparent visual magnitude of +3.53,[2] allowing it to be seen with the naked eye. Wasat is only two-tenths of a degree south of the ecliptic, and therefore is occasionally occulted by the Moon and, more rarely, by a planet. The last occultation by a planet was by Saturn on June 30, 1857, and the next will be by Venus on August 12, 2420.[citation needed] In 1930, the dwarf planet Pluto was discovered about 0.5° to the east of this star by American astronomer Clyde Tombaugh.[10]
In Chinese, 天樽 (Tiān Zūn), meaning Celestial Wine Cup, refers to an asterism consisting of δ Geminorum, 57 Geminorum and ω Geminorum.[12] Consequently, δ Geminorum itself is known as 天樽二 (Tiān Zūn èr, English: the Second Star of Celestial Wine Cup.).[13] From this Chinese name, the name Ta Tsun has appeared.[14]
Properties
Delta Geminorum is a subgiant star with the stellar classification F0 IV.[3] It is about 60.5 light-years (18.5 parsecs) distant.[1] This star has 1.57 times the mass of the Sun[5] and is rotating rapidly with a projected rotational velocity of 129.7 km s−1.[7] The estimated age is 1.6 billion years.[6]
Wasat is a member of a triple star system. The inner components form a spectroscopic binary with a period of 6.1 years (2,238.7 days) and an orbital eccentricity of 0.3530. A cooler class K companion is not apparent to the naked eye but clearly visible in a small telescope. It orbits the inner pair with a period of 1,200 years and an eccentricity of 0.11.[15][16] Although according to [4] its radial velocity is away from the Sun, it is actually approaching the Solar System. In about 1.1 million years, it will make its closest approach at a separation of roughly 6.7 ly (2.1 pc).[17]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 2.0 2.1 2.2 2.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 3.0 3.1 3.2 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 6.0 6.1 6.2 6.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ↑ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Gemini
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
- Delta Geminorum on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
