Binary star system in the constellation Serpens
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! style="text-align: center; background-color: #FFFFC0;" colspan="2" | Observation dataEpoch J2000.0
       Equinox J2000.0 (ICRS)
! style="text-align:left" | Constellation
! style="text-align:left" | Right ascension
! style="text-align:left" | Declination
! style="text-align:left" | Apparent magnitude (V)
! style="background-color: #FFFFC0; text-align: center;" colspan="2"| Characteristics
! style="text-align:left" | Spectral type
! style="text-align:left" | U−B 
! style="text-align:left" | B−V 
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Beta Serpentis, Latinized from β Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with a combined apparent visual magnitude of +3.65. Based upon an annual parallax shift of 21.03 mas as seen from Earth, it is located around 155 light years from the Sun. The system is a member of the Ursa Major Moving Group.
Components.
The visual magnitude +3.68 primary, component A, is either an ordinary A-type main-sequence star or somewhat evolved subgiant with a stellar classification of A2 V or A2 IV, respectively. The star is about 610 million years old with 1.8 the mass of the Sun. It is spinning rapidly with a projected rotational velocity of 216.6 km/s, which causes it to have an oblate shape, as well as hotter temperatures in the poles due to gravity darkening. The equatorial radius measures 4.2 R☉ and has an effective temperature of 6,967 K, while the polar radius measures 3.7 R☉ and has an effective temperature of 9,359 K.
The secondary component, visual magnitude 9.7 B, lies at an angular separation of 30.6 arc seconds. It is a main-sequence star with a class of K3 V.
There is a magnitude +10.98 visual companion, designated component C, located 202 arcseconds away.
Nomenclature.
It was a member of indigenous Arabic asterism al-Nasaq al-Sha'āmī, "the Northern Line" of "al-Nasaqān" "the Two Lines", along with β Her (Kornephoros), γ Her (Hejian, Ho Keen) and γ Ser (Zheng, Ching).
According to the catalogue of stars in the "Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars", "al-Nasaq al-Sha'āmī" or Nasak Shamiya were the title for three stars :β Ser as "Nasak Shamiya I", γ Ser as "Nasak Shamiya II", γ Her as "Nasak Shamiya III" (exclude β Her).
In Chinese, (), 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 β Serpentis, β Herculis, γ Herculis, κ Herculis, γ Serpentis, δ Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi. Consequently, the Chinese name for β Serpentis itself is (, ), represent Zhou (周) (possibly Chow, the dynasty in China), together with η Capricorni and 21 Capricorni in "Twelve States" (asterism).
References.
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