Delta Serpentis

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title: "Delta Serpentis" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["f-type-subgiants", "multiple-star-systems", "delta-scuti-variables", "serpens", "bayer-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects", "stars-with-proper-names", "a-type-subgiants"] description: "Triple star system in the constellation Serpens" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Delta_Serpentis" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Triple star system in the constellation Serpens ::

| image = |image=Serpens constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=δ Serpentis |x=880|y=292 | caption = Location of δ Serpentis (circled in red) | epoch = J2000 | constell = Serpens | ra = | dec = | appmag_v = 3.80 (4.25 + 5.2) | type = | class = A9IV + F0IV | b-v = | u-b = | variable = δ Sct (A) | radial_v = | prop_mo_ra = | prop_mo_dec = | parallax = 14.30 | p_error = 0.75 | parallax_footnote = | absmag_v = −0.42 | component1 = Aa | mass = 1.98 | radius = 4.6 | luminosity = 76 | gravity = 3.46 | temperature = 6,430 | metal_fe = −0.02 | rotational_velocity = 99 | age_gyr = 1.12 | component2 = Ab | mass2 = 1.80 | radius2 = 2.50 | temperature2= 7,270 | age_gyr2 = 1.12 | component1 = B | mass = 1.88 | radius = 3.4 | luminosity = 18.7 | gravity = 3.86 | temperature = 6,660 | metal_fe = −0.17 | rotational_velocity = 84 | age_gyr = 1.26 | names = | component1 = A | names1 = | component2 = B | names2 = | Simbad = del+Ser

Delta Serpentis, Latinized from δ Serpentis, is a hierarchical triple star system in the constellation Serpens, in its head (Serpens Caput). The light from the two stars in the system give a combined apparent magnitude of +3.80, which is bright enough to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 230 light years from the Sun. The system is moving closer with a radial velocity of ~42 km/s, and may come to within 35.23 pc in 1.2 million years.

The primary, component Aa, is a yellow-white F-type subgiant, two times more massive than the Sun, but with 4.6 times the Sun's radius. It is classified as a Delta Scuti type variable star and its magnitude varies by 0.04 with a period of 0.1557 days. It forms a small pair with Ab, a star of undefined spectral type, with a mass 1.8 times the Sun's mass and a radius 2.5 times larger. Both are separated by and complete an orbit around each other every 265 day. They are visible with a combined apparent magnitude of +4.25. The outer, component B, is also an F-type subgiant which is slightly dimmer, with a magnitude of +5.2. A and B are separated by four arcseconds in the sky, and perform one orbit around their centre of mass once every 3,200 years.

Naming

::figure[src="https://upload.wikimedia.org/wikipedia/commons/8/8d/DeltaSerLightCurve.png" caption="TESS]]'' data"] ::

It was a member of the indigenous Arabic asterism al-Nasaq al-Yamānī, "the Southern Line" of al-Nasaqān "the Two Lines", along with α Ser (Unukalhai), ε Ser (Ba), δ Oph (Yed Prior), ε Oph (Yed Posterior), ζ Oph (Han) and γ Oph (Bake-eo).

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 (excluding α Ser, δ Oph, ε Oph, ζ Oph and γ Oph).

In Chinese, 天市右垣 (Tiān Shì Yòu Yuán), meaning Right Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China and which marks 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. Consequently, the Chinese name for δ Serpentis itself is 天市右垣六 (Tiān Shì Yòu Yuán liù, ), representing the state Qin (秦) (or Tsin), together with θ Capricorni and 30 Capricorni (according to Ian Ridpath version) in Twelve States (asterism).

References

References

1. {{in lang. zh ''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.
2. [https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Serpens*.html Star Names - R.H.Allen p.376]
3. {{in lang. zh [http://aeea.nmns.edu.tw/2006/0606/ap060624.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日] {{Webarchive. link. (2019-04-04)
4. {{in lang. zh [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#HeavenlyMarketEnclosure English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name] {{webarchive. link. (August 10, 2010 , Hong Kong Space Museum. Accessed on line November 23, 2010.)
5. {{cite Gaia DR2. 1165987658411028096
6. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics.
7. Waisberg, Idel. (2023-10-01). "Hidden Companions to Intermediate-mass Stars. XII. Discovery of a 1.8 {{solar mass}}, 1.3 au Companion to Delta Serpentis A". Research Notes of the American Astronomical Society.
8. Stassun K.G.. (October 2019). "The revised TESS Input Catalog and Candidate Target List". [[The Astronomical Journal]].
9. "del Ser".
10. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series.

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