Beta Capricorni
Encyclopedia
Beta Capricorni is a star system
in the constellation
Capricornus
. It has the traditional name Dabih, which comes from the Arabic
الذابح al-dhābiḥ, meaning "the butcher". The β Capricorni system is located 328 light years from Earth. Because it is near the ecliptic
, β Capricorni can be occulted
by the Moon
, and also (rarely) by planet
s.
In Chinese
, , meaning Ox
(asterism), refers to an asterism consisting of β Capricorni, α2 Capricorni, ξ2 Capricorni
, π Capricorni
, ο Capricorni
and ρ Capricorni
. Consequently, β Capricorni itself is known as
into a double star
. The brighter of these two components, β¹ Capricorni or Dabih Major, has an apparent magnitude
of +3.05, while the dimmer one, β² Capricorni or Dabih Minor, has an apparent magnitude of +6.09. The two components are separated by 3.5 arcminutes on the sky, putting them at leat 21,000 AU
(0.34 light years) apart. They take approximately 700,000 years to complete one orbit. Both of these components are themselves made up of multiple stars.
Due to the complexity of this system, several different schemes have arisen to denote the subcomponents. This article follows the naming used in the Multiple Star Catalogue.
bright giant
β Capricorni Aa, with an apparent magnitude of +3.08, and the blue-white B-Type
main sequence dwarf
, β Capricorni Ab with an apparent magnitude of +7.20. These two components are separated by 0.05 arcseconds (5 AU) and have an orbital period
of 3.77 years.
The Aa component has a surface temperature of 4900 kelvins, a diameter of 35 times that of the Sun
, and a luminosity
600 times that of the Sun. The Ab component has another, unseen companion, β Capricorni Ac, which orbits Ab with an orbital period of 8.7 days. It is thought that the Aa component is itself multiple.
with 40 times the luminosity of the Sun. The companion, β Capricorni C, is approximately 3 arcseconds from B. β Capricorni B is unusual for having large amounts of mercury
and manganese
in its atmosphere.
. These lie 112 arcseconds away from β¹ Capricorni, and it is unclear whether they are simply optical doubles or part of the β Capricorni system. They are sometimes referred to as β Capricorni D and E.
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....
Capricornus
Capricornus
Capricornus is one of the constellations of the zodiac; it is often called Capricorn, especially when referring to the corresponding astrological sign. Its name is Latin for "horned male goat" or "goat horn", and it is commonly represented in the form of a sea-goat: a mythical creature that is half...
. It has the traditional name Dabih, which comes 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...
الذابح al-dhābiḥ, meaning "the butcher". The β Capricorni system is located 328 light years from Earth. Because it is near the ecliptic
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
, β Capricorni can be occulted
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
by the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
, and also (rarely) by planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s.
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 Ox
Ox (Chinese constellation)
The Ox mansion is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise.-Asterisms:...
(asterism), refers to an asterism consisting of β Capricorni, α2 Capricorni, ξ2 Capricorni
Xi2 Capricorni
Xi2 Capricorni is a star in the constellation Capricornus. ξ2 Capricorni is a yellow-white F-type main sequence dwarf with an apparent magnitude of +5.84. It is approximately 91.5 light years from Earth....
, π Capricorni
Pi Capricorni
Pi Capricorni is a double star in the constellation Capricornus. It also has the traditional star name Okul or Oculus...
, ο Capricorni
Omicron Capricorni
Omicron Capricorni is a binary star in the constellation Capricornus. It is approximately 137 light years from Earth....
and ρ Capricorni
Rho Capricorni
Rho Capricorni is a binary star in the constellation Capricornus. It is approximately 98.7 light years from Earth.Sometimes, this star is called by the name Bos, meaning the cow in Latin....
. Consequently, β Capricorni itself is known as
Visual double
With binoculars or a small telescope, β Capricorni can be resolvedOptical resolution
Optical resolution describes the ability of an imaging system to resolve detail in the object that is being imaged.An imaging system may have many individual components including a lens and recording and display components...
into a double star
Double star
In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
. The brighter of these two components, β¹ Capricorni or Dabih Major, 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 +3.05, while the dimmer one, β² Capricorni or Dabih Minor, has an apparent magnitude of +6.09. The two components are separated by 3.5 arcminutes on the sky, putting them at leat 21,000 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
(0.34 light years) apart. They take approximately 700,000 years to complete one orbit. Both of these components are themselves made up of multiple stars.
Due to the complexity of this system, several different schemes have arisen to denote the subcomponents. This article follows the naming used in the Multiple Star Catalogue.
β¹ Capricorni
The brighter component, β¹ Capricorni, is the more complex of the pair. It has at least three components, and its spectrum is difficult to interpret. It is dominated by a pair of stars, the orange K-typeStellar 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...
bright giant
Bright giant
The luminosity class II in the Yerkes spectral classification is given to bright giants. These are stars which straddle the boundary between giants and supergiants, and the classification is in general given to giant stars with exceptionally high luminosity, but which are not sufficiently bright...
β Capricorni Aa, with an apparent magnitude of +3.08, and the blue-white B-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...
, β Capricorni Ab with an apparent magnitude of +7.20. These two components are separated by 0.05 arcseconds (5 AU) and have an orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
of 3.77 years.
The Aa component has a surface temperature of 4900 kelvins, a diameter of 35 times that of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, and a luminosity
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...
600 times that of the Sun. The Ab component has another, unseen companion, β Capricorni Ac, which orbits Ab with an orbital period of 8.7 days. It is thought that the Aa component is itself multiple.
β² Capricorni
The dimmer of the visual double star, β¹ Capricorni, is simpler and more studied. It is a binary star, whose brighter component, β Capricorni B, has a magnitude of 6.1. It is a A0-giantGiant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...
with 40 times the luminosity of the Sun. The companion, β Capricorni C, is approximately 3 arcseconds from B. β Capricorni B is unusual for having large amounts of mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
and manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
in its atmosphere.
Other components
Two other nearby stars were discovered by John HerschelJohn Herschel
Sir John Frederick William Herschel, 1st Baronet KH, FRS ,was an English mathematician, astronomer, chemist, and experimental photographer/inventor, who in some years also did valuable botanical work...
. These lie 112 arcseconds away from β¹ Capricorni, and it is unclear whether they are simply optical doubles or part of the β Capricorni system. They are sometimes referred to as β Capricorni D and E.