Beta Serpentis, Latinized from β Serpentis, is a binary star[3] 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.[2] Based upon an annual parallax shift of 21.03 mas as seen from Earth,[1] it is located around 155 light years from the Sun. The system is a member of the Ursa Major Moving Group.[7]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Serpens |
| Right ascension | 15h 46m 11.25435s[1] |
| Declination | +15° 25′ 18.5959″[1] |
| Apparent magnitude (V) | +3.65[2] (3.68 + 9.7)[3] |
| Characteristics | |
| Spectral type | A2 V[4] or A2 IV[5] + K3 V[3] |
| U−B color index | +0.09[2] |
| B−V color index | +0.073[4] |
| Astrometry | |
| Radial velocity (Rv) | +0.6±0.3[6] km/s |
| Proper motion (μ) | RA: +65.38[1] mas/yr Dec.: −38.61[1] mas/yr |
| Parallax (π) | 21.03 ± 0.26 mas[1] |
| Distance | 155 ± 2 ly (47.6 ± 0.6 pc) |
| Absolute magnitude (MV) | +0.30/+6.59[7] |
| Details | |
| Mass | 1.94[8] M☉ |
| Surface gravity (log g) | 3.27[8] cgs |
| Temperature | 8,928±304[8] K |
| Rotational velocity (v sin i) | 207±10.4[4] km/s |
| Age | 267[8] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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[4] or A2 IV,[5] respectively. The star is about 267 million years old with nearly double the mass of the Sun.[8] It is spinning rapidly with a projected rotational velocity of 207 km/s.[4]
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.[3]
There is a magnitude +10.98 visual companion, designated component C, located 202 arcseconds away.[10]
Nomenclature
It was a member of indigenous Arabic asterism al-Nasaq al-Sha'āmī, "the Northern Line" of al-Nasaqān "the Two Lines",[11] along with β Her (Kornephoros), γ Her (Hejian, Ho Keen) and γ Ser (Zheng, Ching).[12]
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).[13]
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 β Serpentis, β Herculis, γ Herculis, κ Herculis, γ Serpentis, δ Serpentis, α Serpentis, ε Serpentis, δ Ophiuchi, ε Ophiuchi and ζ Ophiuchi.[14] Consequently, the Chinese name for β Serpentis itself is 天市右垣五 (Tiān Shì Yòu Yuán wu, English: the Fifth Star of Right Wall of Heavenly Market Enclosure), represent Zhou (周) (possibly Chow, the dynasty in China),[15][16][17] together with η Capricorni and 21 Capricorni in Twelve States (asterism).[18]