Delta Herculis (δ Herculis, abbreviated Delta Her, δ Her) is a
multiple 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 ...
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted th ...
. Its light produces to us
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 li ...
3.12, as such the third-brightest star in the large, fairly dim constellation. 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 ...
measurement taken during the
Hipparcos
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial obj ...
It consists of a binary pair, designated Delta Herculis A, together with three potential companions, suffixed B, C and D. Furthermore B is believed to be an optical binary. A's components are designated Delta Herculis Aa (officially named Sarin , the traditional name of the system) and Ab.
The angular separation between the main component A and the component B, which has a magnitude of 8.74, is 8.5 arcsecond
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. T ...
. The designations of the four constituents as ''Delta Herculis A'', ''B'', ''C'' and ''D'', and those of ''A's'' components - ''Delta Herculis Aa'' and ''Ab'' - derive from the convention used by the Washington Multiplicity Catalog (WMC) for
multiple 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 ...
s, and adopted by the
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
(IAU).
It bore the traditional name ''Sarin''. In 2016, the
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
organized a
Working Group on Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize List of proper names of stars, proper names for stars for the international astronomical community. It operates under ...
(WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name ''Sarin'' for the component Delta Herculis Aa on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In the catalogue of stars in the ''Calendarium'' of
Al Achsasi al Mouakket
Muḥammad al-Akhṣāṣī al-Muwaqqit ( ar, محمد الاخصاصي الموقت) was an Egyptian astronomer whose and catalogue of stars, ('Pearls of brilliance upon the solar operations'), was written at Cairo about 1650.
Al-Akhsasi was a ...
, this star was designated ''Menkib al Jathi al Aisr'', which was translated into
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
as ''Humerus Sinister Ingeniculi'', meaning ''kneeler's left shoulder''.
In Chinese, (), meaning '' Left Wall of Heavenly Market Enclosure'', refers to an asterism which represents eleven old states in China which is marking the left borderline of the enclosure, consisting of Delta Herculis,
Lambda Herculis
Lambda Herculis (λ Herculis. abbreviated Lambda Her, λ Her), formally named Maasym , is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the Sun. ...
,
Mu Herculis
Mu Herculis (μ Herculis) is a nearby quadruple star system about 27.1 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a stellar ...
,
Omicron Herculis
Omicron Herculis, Latinized from o Herculis, is a star in the constellation Hercules. It used to be called Masym ("the wrist"), but this name was transferred to Lambda Herculis.
Properties
Omicron Herculis is a B9.5III star approxim ...
,
112 Herculis
112 Herculis is a binary star system in the northern constellation of Hercules. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.43. The secondary component is about two magnitudes fainter than the pr ...
,
Zeta Aquilae
Zeta Aquilae, or ζ Aquilae, is a binary star system in the equatorial constellation of Aquila. It is readily visible with the naked eye, being of the third magnitude. Based on parallax measurements obtained during the Hipparcos mission, ...
Nu Ophiuchi
Nu Ophiuchi (ν Oph, ν Ophiuchi) is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude is +3.3, making it one of the brighter members of this constellation. Based upon parallax measurements made during ...
Eta Ophiuchi
Eta Ophiuchi (η Ophiuchi, abbreviated Eta Oph, η Oph) is a binary star in the constellation of Ophiuchus. Based on parallax measurements taken during the Hipparcos mission, it is approximately 88 light-years from the Sun.
Eta Ophiu ...
. 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 oft ...
for Delta Herculis itself is (, en, the First Star of Left Wall of Heavenly Market Enclosure), and represents the state of
Wei
Wei or WEI may refer to:
States
* Wey (state) (衛, 1040–209 BC), Wei in pinyin, but spelled Wey to distinguish from the bigger Wei of the Warring States
* Wei (state) (魏, 403–225 BC), one of the seven major states of the Warring States per ...
(魏), together with
33 Capricorni
33 may refer to:
*33 (number)
*33 BC
*AD 33
*1933
*2033
Music
* ''33'' (Luis Miguel album) (2003)
* ''33'' (Southpacific album) (1998)
* ''33'' (Wanessa album) (2016)
*"33 'GOD'", a 2016 song by Bon Iver
* "Thirty-Three" (song), a 1995 song by th ...
main-sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...
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 spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...
of A3IV. It has both a mass and radius that are roughly two times solar yielding a total
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a s ...
Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted th ...