Theta Serpentis
Encyclopedia
Theta Serpentis is a star system
in the constellation
Serpens
. It is approximately 132 light years from Earth. Theta Serpentis also has the traditional name Alya, or Alga, from the Arabic
الية ’alyah "fat tail
(of a sheep)".
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket
, this star was designated Dzaneb al Haiyet, which was translated into Latin
as Cauda Serpentis, meaning the serpent's tail.
In Chinese
, , meaning Left Wall of Heavenly Market Enclosure
, refers to an asterism which is represent eleven old states in China, consisting of θ Serpentis, δ Herculis
, λ Herculis
, μ Herculis
, ο Herculis
, 112 Herculis, ζ Aquilae
, η Serpentis
, ν Ophiuchi
, ξ Serpentis
and η Ophiuchi
. Consequently, θ Serpentis itself is known as , represent the state Xu
(徐).
Both Theta-1 Serpentis and Theta-2 Serpentis are white A-type
main sequence dwarf
s. θ¹ has an apparent magnitude
of +4.62 while the slightly dimmer θ² has a magnitude
of +4.98. These two stars are 22 arcseconds apart on the sky, putting them at least 900 astronomical unit
s apart with an orbital period of at least 14,000 years. Both stars are similar to each other in all respects, having luminosities
of 18 and 13 times solar respectively, radii of about twice solar and also masses
of roughly 2 times that of our Sun. Both star have a surface temperature of 8,000 kelvin
s.
The third star in the system, Theta Serpentis C, is a yellow G-type star with an apparent magnitude of +6.71. It is separated by 7 arcminutes from θ².
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Serpens
Serpens
Serpens is a constellation of the northern hemisphere. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy and it remains one of the 88 modern constellations defined by the International Astronomical Union....
. It is approximately 132 light years from Earth. Theta Serpentis also has the traditional name Alya, or Alga, from the Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
الية ’alyah "fat tail
Fat-tailed sheep
The fat-tailed sheep is a general type of domestic sheep known for their distinctive large tails and hindquarters. Fat-tailed sheep breeds comprise approximately 25% of the world sheep population, and are commonly found in northern parts of Africa, the Middle East, Pakistan, North India, Western...
(of a sheep)".
In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket
Al Achsasi al Mouakket
Mohammad Al Achsasi Al Mouakket was an Egyptian astronomer whose calendarium and catalogue of stars, entitled Durret al Muddiah Fih al Aamal al Shamsiah , was written at Cairo about 1650.Al Achsasi was sheikh of the Grand Mosque of the University of Cairo, where his name al...
, this star was designated Dzaneb al Haiyet, which was translated into Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
as Cauda Serpentis, meaning the serpent's tail.
In Chinese
Chinese language
The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...
, , meaning Left Wall of Heavenly Market Enclosure
Heavenly Market enclosure
Tian Shi Yuan, the Heavenly Market Enclosure , is one of the San Yuan or Three enclosures. Stars and constellations of this group are visible during late summer and early autumn in the Northern Hemisphere . The summer triangle lies directly to the northwest.-Asterisms:The asterisms are :...
, refers to an asterism which is represent eleven old states in China, consisting of θ Serpentis, δ Herculis
Delta Herculis
Delta Herculis is a fourth-magnitude star in the constellation Hercules. It has the traditional name Sarin....
, λ Herculis
Lambda Herculis
Lambda Herculis is a star inthe constellation Hercules.It has the traditional name Maasym .In Chinese, , meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking the left borderline of the enclosure, consisting of λ...
, μ Herculis
Mu Herculis
Mu Herculis is a nearby 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...
, ο Herculis
Omicron Herculis
Omicron Herculis is a multiple star system in the constellation Hercules. It has the traditional name Atia and the Flamsteed designation 103 Herculis.- Properties :...
, 112 Herculis, ζ Aquilae
Zeta Aquilae
Zeta Aquilae is a triple star system in the constellation Aquila. It has the traditional names Deneb el Okab, from an Arabic term ذنب العقاب ðanab al-cuqāb meaning "the tail of the falcon", and the Mandarin names Woo and Yuë, derived from and represent the state Wu , an old state was located at...
, η Serpentis
Eta Serpentis
Eta Serpentis is a binary star in the constellation Serpens. The primary, Eta Serpentis A, is an orange K-type giant with an apparent magnitude of +3.23. It has a distant 12th magnitude companion, Eta Serpentis B, 3 arcminutes away...
, ν Ophiuchi
Nu Ophiuchi
Nu Ophiuchi is a Class K0, third-magnitude star in the constellation Ophiuchus. Its closest stellar neighbour is the bright binary system Tau Ophiuchi, roughly 16.9 light years away from the star...
, ξ Serpentis
Xi Serpentis
Xi Serpentis is a triple star system in the constellation Serpens. The primary star, Xi Serpentis A, is a yellow-white F-type giant with an apparent magnitude of +3.54. It is a spectroscopic binary with an orbital period of 2.29 days. A 13th magnitude companion, Xi Serpentis B, is located 25...
and η Ophiuchi
Eta Ophiuchi
Eta Ophiuchi, also known as η Oph or η Ophiuchi, is a star in the constellation Ophiuchus. It also has the traditional name Sabik....
. Consequently, θ Serpentis itself is known as , represent the state Xu
Xu (state)
The State of Xu was a vassal state of ancient China during the Zhou Dynasty and Spring and Autumn Period ruled by descendants of the Yíng family. Xu was a Dongyi state also known as Xurong , Xuyi or Xufang , all meaning either "Xu barbarians" or "Xu Proper". Xu was one of the largest and most...
(徐).
Both Theta-1 Serpentis and Theta-2 Serpentis are white A-type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
main sequence dwarf
Main sequence
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 Hertzsprung and Henry Norris Russell...
s. θ¹ has an apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of +4.62 while the slightly dimmer θ² has a magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of +4.98. These two stars are 22 arcseconds apart on the sky, putting them at least 900 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s apart with an orbital period of at least 14,000 years. Both stars are similar to each other in all respects, having luminosities
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
of 18 and 13 times solar respectively, radii of about twice solar and also masses
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
of roughly 2 times that of our Sun. Both star have a surface temperature of 8,000 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
s.
The third star in the system, Theta Serpentis C, is a yellow G-type star with an apparent magnitude of +6.71. It is separated by 7 arcminutes from θ².