Xi Geminorum
 Location of ξ Geminorum (circled) |
|
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 45m 17.36432s[1] |
| Declination | +12° 53′ 44.1311″[1] |
| Apparent magnitude (V) | 3.35[2] |
| Characteristics | |
| Spectral type | F5 IV[3] |
| U−B color index | +0.06[4] |
| B−V color index | +0.43[4] |
| Astrometry | |
| Radial velocity (Rv) | +25.6[2] km/s |
| Proper motion (μ) | RA: –115.73[1] mas/yr Dec.: –190.55[1] mas/yr |
| Parallax (π) | 55.56 ± 0.19[1] mas |
| Distance | 58.7 ± 0.2 ly (18.00 ± 0.06 pc) |
| Absolute magnitude (MV) | 2.14[5] |
| Details | |
| Mass | 1.706 ± 0.012[6] M☉ |
| Radius | 2.710 ± 0.021[6] R☉ |
| Luminosity | 11.574 ± 0.238[6] L☉ |
| Surface gravity (log g) | 3.81 ± 0.02[7] cgs |
| Temperature | 6,480 ± 39[6] K |
| Metallicity [Fe/H] | 0.00 ± 0.01[7] dex |
| Rotational velocity (v sin i) | 66.1 ± 3.3[8] km/s |
| Age | 1.5[9] Gyr |
| Other designations | |
Xi Geminorum (ξ Gem) is a star in the zodiac constellation Gemini with the traditional name Alzirr.[10] It forms one of the four feet of the outline demarcating the Gemini twins.[11] The star has an apparent visual magnitude of 3.35,[2] which is bright enough for it to be seen with the naked eye. From parallax measurements, its distance from the Earth can be estimated as 58.7 light-years (18.0 parsecs).[1]
Alzirr has a stellar classification of F5 IV,[3] which is subgiant star that is in the process of evolving away from the main sequence of stars like the Sun. It has about 162%[5] of the Sun's mass and is radiating more than 11 times the luminosity of the Sun.[7] This energy is being emitted from the outer envelope of the star at an effective temperature of 6,464 K.[7] This causes the star to take on the yellow-white hue common to F-type stars.[12]
X-ray emission has been detected from this star, which has an estimated X-ray luminosity of 1.06 × 1029 erg s−1.[5] It has the spectroscopic signature of a rapidly rotating star, with a projected rotational velocity of about 66 km s−1.[8] Although generally considered a single star, there is some evidence that it may instead be a spectroscopic binary system consisting of two component stars of equal mass.[13]
Name
The proper name of Xi Geminorum is Alzirr, meaning "the button" in Arabic. This star, along with γ Gem (Alhena), μ Gem (Tejat Posterior), ν Gem and η Gem (Tejat Prior) were Al Han'ah, "the brand" (on the neck of the camel). They also were associated in Al Nuḥātai, the dual form of Al Nuḥāt, "a Camel's Hump".[10]
In Chinese, 井宿 (Jǐng Su), meaning Well (asterism), refers to an asterism consisting of ξ Geminorum, μ Geminorum, ν Geminorum, γ Geminorum, ε Geminorum, 36 Geminorum, ζ Geminorum and λ Geminorum.[14] Consequently, ξ Geminorum itself is known as 井宿四 (Jǐng Su sì, English: the Fourth Star of Well.)[15]
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 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 5.2 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.. See Table 10 & 12.
- ↑ 7.0 7.1 7.2 7.3 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 10.0 10.1 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.
- ↑ (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.
External links
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