Alpha Aquarii
Encyclopedia
| name = α Aquarii
}}
Alpha Aquarii (Alpha Aqr, α Aquarii, α Aqr), which also has the traditional name Sadalmelik, is the second-brightest star
in the constellation
Aquarius
. It is a G-type supergiant
(yellow supergiant
) star
in the constellation
of Aquarius
, with an apparent visual magnitude of approximately 2.950, approximately 800 light-years from the Earth
. It has a diameter approximately 60 times that of the Sun
, and a luminosity
which is 3,000 times greater than the Sun's.
The name Sadalmelik derives from an Arabic
expression سعد الملك sa‘d al-malik meaning "Luck of the king". Ulug Beg was combined the name with ο Aqr
. The name Rucbah has also been applied to this star; it shares this name with Delta Cassiopeiae
. It is only one of two stars with ancient proper names to lie within a degree of the celestial equator. The origin of the Arabic name is lost to history.
In Chinese
, , meaning Rooftop
(asterism), refers to an asterism consisting of α Aquarii, θ Pegasi
and ε Pegasi. Consequently, α Aquarii itself is known as
, designated CCDM J22058-0019B, with an apparent visual magnitude of approximately 12.2.
Bayer designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek letter, followed by the genitive form of its parent constellation's Latin name...
}}
Alpha Aquarii (Alpha Aqr, α Aquarii, α Aqr), which also has the traditional name Sadalmelik, is the second-brightest star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
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....
Aquarius
Aquarius (constellation)
Aquarius is a constellation of the zodiac, situated between Capricornus and Pisces. Its name is Latin for "water-bearer" or "cup-bearer", and its symbol is , a representation of water....
. It is a G-type supergiant
Supergiant
Supergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
(yellow supergiant
Yellow supergiant
A yellow supergiant is a supergiant star of spectral type F or G. These stars usually have masses between 15 and 20 solar masses. These stars, like any other supergiant,...
) star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
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....
of Aquarius
Aquarius (constellation)
Aquarius is a constellation of the zodiac, situated between Capricornus and Pisces. Its name is Latin for "water-bearer" or "cup-bearer", and its symbol is , a representation of water....
, with an apparent visual magnitude of approximately 2.950, approximately 800 light-years from the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
. It has a diameter approximately 60 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...
which is 3,000 times greater than the Sun's.
The name Sadalmelik derives from an 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...
expression سعد الملك sa‘d al-malik meaning "Luck of the king". Ulug Beg was combined the name with ο Aqr
Omicron Aquarii
Omicron Aquarii is a star in the constellation Aquarius. It has the traditional star name Kae Uh, from the Chinese 蓋屋 "the roof"....
. The name Rucbah has also been applied to this star; it shares this name with Delta Cassiopeiae
Delta Cassiopeiae
Delta Cassiopeiae is a star in the constellation Cassiopeia. It has the traditional names Ksora and Ruchbah, derived from the Arabic word ركبة rukbah meaning "knee"...
. It is only one of two stars with ancient proper names to lie within a degree of the celestial equator. The origin of the Arabic name is lost to history.
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 Rooftop
Rooftop (Chinese constellation)
The Rooftop 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 α Aquarii, θ Pegasi
Theta Pegasi
Theta Pegasi is a star in the constellation Pegasus. It has the traditional name Baham .In Chinese, , meaning Rooftop, refers to an asterism consisting of θ Pegasi, α Aquarii and ε Pegasi. Consequently, θ Pegasi itself is known as Theta Pegasi is of spectral class A2 and has apparent magnitude...
and ε Pegasi. Consequently, α Aquarii itself is known as
Visual companion
Sadalmelik has a visual companionDouble 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...
, designated CCDM J22058-0019B, with an apparent visual magnitude of approximately 12.2.