Delta Serpentis

δ Serpentis

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Serpens
Right ascension	15h 34m 48.1s
Declination	+10° 32' 15"
Apparent magnitude (V)	combined: +3.80 AB: 4.2 + 5.2 CD: 14.7 + 15.2
Distance	210 ± 11 ly (64 ± 3 pc)
Spectral type	AB: F0IV + F0IV
Other designations
13 Serpentis, HR 5788, HD 138917 + HD 138918, SAO 101623 + SAO 101624, HIP 76276, ADS 9701, CCDM 15348+1033

Delta Serpentis (δ Serpentis, δ Ser) is a star system in the constellation Serpens, in its head (Serpens Caput). It was a member of indigenous Arabic asterism al-Nasaq al-Yamānī, "the Southern Line" of al-Nasaqān "the Two Lines".^[1], along with α Ser (Unukalhai), ε Ser (Ba, Pa), δ Oph (Yed Prior), ε Oph (Yed Posterior), ζ Oph (Han) and γ Oph (Tsung Ching).^[2]

According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, al-Nasaq al-Yamānī or Nasak Yamani were the title for two stars :δ Ser as Nasak Yamani I and ε Ser as Nasak Yamani II (exclude α Ser, δ Oph, ε Oph, ζ Oph and γ Oph)^[3]

In Chinese, 天市右垣 (Tiān Shì Yòu Yuán), meaning Right Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking the right borderline of the enclosure, consisting of δ Serpentis, β Herculis, γ Herculis, κ Herculis, γ Serpentis, β Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi ^[4]. Consequently, δ Serpentis itself is known as 天市右垣六 (Tiān Shì Yòu Yuán liù, English: the Sixth Star of Right Wall of Heavenly Market Enclosure), represent the state Qin (秦) (or Tsin)^[5][6][7], together with θ Capricorni and 30 Capricorni in Twelve States (asterism).^[8]

Properties

It is approximately 210 light years from Earth. The light from the four stars in the system give a combined apparent magnitude of +3.80.

The system consists of a pair of binary stars separated by 66 arcseconds. The primary component, Delta Serpentis A, is a yellow-white F-type subgiant with an apparent magnitude of +4.2. It is classified as a Delta Scuti type variable star and its magnitude varies by 0.04 with a period of 0.134 days. Its binary companion, Delta Serpentis B, is also a F-type subgiant which is slightly dimmer, with a magnitude of +5.2. A and B are separated by four arcseconds on the sky, and perform one orbit around their centre of mass once every 3200 years. The 14th magnitude stars Delta Serpentis C and 15th magnitude Delta Serpentis D form the second binary sub-system. They are separated from each other by 4.4 arcseconds.

References

1. ^ Kunitzsch, P., Smart, T., (2006). A Dictionary of Modern Star names: A Short Guide to 254 Star names and Their Derivations (Second Revised ed.). Cambridge, MA: Sky Publishing. p. 31. ISBN 1931559449. 
2. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York, NY: Dover Publications Inc. p. 243. ISBN 0486210790. http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Hercules*.html. Retrieved 2010-12-12. 
3. ^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
4. ^ (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 9789867332257.
5. ^ Star Names - R.H.Allen p.376
6. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日
7. ^ (Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name, Hong Kong Space Museum. Accessed on line November 23, 2010.
8. ^ Star Names - R.H.Allen p.142