Beta Serpentis, Latinized from β Serpentis, also named Zhou, is a binary star system in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

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 year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s from the Sun. The system is a member of the

Ursa Major Moving Group The Ursa Major Moving Group, also known as Collinder 285 and the Ursa Major association, is the closest Stellar kinematics#Moving groups, stellar moving group – a set of stars with common velocities in space and thought to have a common orig ...

Components

The visual magnitude +3.68 primary, component A, is either an ordinary A-type main-sequence star or somewhat evolved

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

with a

stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...

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 Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bu ...

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 and has an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of 6,967 K, while the polar radius measures 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 second A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s. 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

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s 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),
AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日

, Hong Kong Space Museum. Accessed on line November 23, 2010. together with η Capricorni and 21 Capricorni in '' Twelve States'' (asterism). The IAU Working Group on Star Names approved the name Zhou for this star on 5 December 2024 and it is now so entered in the IAU Catalog of Star Names.

References

{{DEFAULTSORT:Beta Serpentis A-type main-sequence stars A-type subgiants K-type main-sequence stars Binary stars Ursa Major moving group Serpentis, Beta Serpens BD+15 2911 Serpentis, 28 141003 077233 5867 Zhou