Delta Serpentis, Latinized from δ Serpentis, is a binary

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or ''galaxy'', although, broadly speaking ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...

Serpens Serpens ( grc, , , the Serpent) is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International ...

, in its head (Serpens Caput). The light from the two stars in the system give a combined

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of +3.80, which is bright enough to be visible to the naked eye. Based on

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...

measurements, it is located at a distance of approximately 230

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. The system is moving closer with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

of ~42 km/s, and may come to within in 1.2 million years. The primary, component A, is a yellow-white F-type

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 an

of +4.25. It is classified as a Delta Scuti type

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

and its magnitude varies by 0.04 with a period of 0.1557 days. Its binary companion, 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

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

s in the sky, and perform one orbit around their centre of mass once every 3,200 years.

Naming

It was a member of indigenous Arabic asterism ''al-Nasaq al-Yamānī'', "the Southern Line" of ''al-Nasaqān'' "the Two Lines", 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). 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) 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 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 Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...

for δ Serpentis itself is (, en, the Sixth Star of Right Wall of Heavenly Market Enclosure), representing the state Qin (秦) (or Tsin),
AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 24 日
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, Hong Kong Space Museum. Accessed on line November 23, 2010. together with θ Capricorni and 30 Capricorni (according to Ian Ridpath version) in '' Twelve States'' (asterism).

References

{{DEFAULTSORT:Delta Serpentis F-type subgiants 4 Delta Scuti variables Serpens (constellation) Serpentis, Delta Durchmusterung objects Serpentis, 13 138917 8 076276 5788 Nasak Yamani I A-type subgiants