Eta Geminorum
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| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 14m 52.657 / 52.567s |
| Declination | +22° 30′ 24.48 / 24.51″ |
| Apparent magnitude (V) | 3.15 to 3.9 / 8.8 |
| Absolute magnitude (V) | -2.0 to -1.2 / 3.6 |
| Distance | 350±70 ly (110±20 pc) |
| Spectral type | M3IIIab / G0 |
| Other designations | |
| Data sources: | |
| Hipparcos Catalogue, CCDM (2002), GCVS (4.2) |
|
Eta Geminorum (η Gem, η Geminorum) is a triple star system in the constellation Gemini. It has the traditional names Tejat Prior, Propus (from the Greek, meaning forward foot) and Praepes and Pish Pai (from the Persian Pīshpāy, پیشپای, meaning foreleg).[1]
This star, along with γ Gem (Alhena), μ Gem (Tejat Posterior), ν Gem and ξ Gem (Alzirr) 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".[2]
In Chinese lunar mansion, Tejat Prior is the only member of the lunar mansion 钺 (Pinyin: Yuè, Chinese "Battle Axe").[3][4]
Properties
Eta Geminorum A is a spectroscopic binary. The primary is a semiregular variable star of type SRA whose brightness changes with a period of 234 days between magnitude +3.15 and +3.9. It is located 350 light years from the Sun and is a red giant of the spectral type M3. The secondary, probably a class B, orbits with a period of 8.2 years. Eta Geminorum B, a class G dwarf, orbits the pair with a period of at least 700 years.[5],[6]
Eta Geminorum is near the ecliptic, so it can be occulted by the Moon and, very rarely, by planets. The last occultation by a planet took place on July 27, 1910, by Venus, and the next to last on July 11, 1837, by Mercury.
Namesakes
USS Propus (AK-132) was a United States Navy Crater class cargo ship named after the star.
References
- ↑ p. 235, Star-names and Their Meanings, Richard Hinckley Allen, G. E. Stechert, 1899.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 26 日
- ↑ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Gemini
- ↑ The Spectrographic Orbit and Light-Variations of η Geminorum, Dean B. McLaughlin and Suzanne E. A. van Dijke, Astrophysical Journal 100 (July 1944), pp. 63–68.
- ↑ Eta Geminorum at Jim Kaler's STARS.
