Delta Herculis
 Historical view of the Hercules constellation showing the star Sarin (δ Her) next to the Keystone asterism. |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Hercules |
| Right ascension | 17h 15m 01.9106s[1] |
| Declination | 24° 50′ 21.135″[1] |
| Apparent magnitude (V) | 3.126[1] |
| Characteristics | |
| Spectral type | A3IV[1] |
| U−B color index | +0.7[2] |
| B−V color index | +0.08[2] |
| Astrometry | |
| Radial velocity (Rv) | -40.0[1] km/s |
| Proper motion (μ) | RA: -21.14[1] mas/yr Dec.: -157.68[1] mas/yr |
| Parallax (π) | 43.41 ± 0.15[3] mas |
| Distance | 75.1 ± 0.3 ly (23.04 ± 0.08 pc) |
| Absolute magnitude (MV) | +1.31 |
| Details | |
| Mass | 2.4[4] M☉ |
| Radius | 2.2[4] R☉ |
| Luminosity | 38[4] L☉ |
| Temperature | 9,620 ± 350[4] K |
| Rotational velocity (v sin i) | 270[5] km/s |
| Age | 370[5] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Delta Herculis (δ Her, δ Herculis) is a fourth-magnitude star in the constellation Hercules. It has the traditional name Sarin.[6][7]
Properties
Sarin is a complex star system consisting of at least 2 stars and possibly as many as 5. The main star is an A Type main sequence subgiant with a stellar classification A3IV. The subgiant has both a mass and radius that are roughly two times solar yielding a total luminosity of about 18.5 L☉[5] Though it only shines with an apparent magnitude of 3.12, it the third brightest star in the Hercules constellation. The most recent Hipparcos data yields a distance estimate of approximately 23.1 parsecs (pc) from Earth or 75 light years (ly).
In culture
In Chinese, 天市左垣 (Tiān Shì Zuǒ Yuán), meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking the left borderline of the enclosure, consisting of δ Herculis, λ Herculis, μ Herculis, ο Herculis, 112 Herculis, ζ Aquilae, θ1 Serpentis, η Serpentis, ν Ophiuchi, ξ Serpentis and η Ophiuchi.[8] Consequently, δ Herculis itself is known as 天市左垣一 (Tiān Shì Zuǒ Yuán yī, English: the First Star of Left Wall of Heavenly Market Enclosure), represent the state Wei (魏),[9][10] together with 33 Capricorni (φ Capricorni and χ Capricorni in R.H. Allen's version)[11] in Twelve States (asterism).
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Menkib al Jathi al Aisr, which was translated into Latin as Humerus Sinister Ingeniculi, meaning the left shoulder of the kneeling man.[12]
See also
- Lists of stars in the constellation Hercules
- Class A Stars
- Star system
References
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- Jim Kaler's Stars, University of Illinois: DELTA HER (Delta Herculis)
- An Atlas of the Universe: Multiple Star Orbits
Coordinates: 
17h 15m 01.910s, +24° 50′ 21.135″
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- ↑ (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.
- ↑ (Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name, Hong Kong Space Museum. Accessed on line November 23, 2010.
- ↑ Star Names - R.H.Allen p.142
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
