Beta Aquarii is a single [14] yellow supergiant star in the constellation of Aquarius. It has the official name Sadalsuud ( /ˌsædəlˈsuːəd/ ) [15] and the Bayer designation β Aquarii, abbreviated Beta Aqr or β Aqr. Based upon parallax measurements obtained during the Hipparcos mission, this component is located at a distance of approximately 540 light years (165 parsecs) from the Sun. [1] It is drifting further away with a radial velocity of 6.5 km/s. [4] The star serves as an IAU radial velocity standard. [16]
β Aquarii, Latinised to Beta Aquarii, is the star's Bayer designation.
It bore the traditional name Sadalsuud, from an Arabic expression سعد السعود (sa‘d al-su‘ūd), the "luck of lucks". Other spellings that were sometimes encountered were Sad es Saud, Sadalsund, and Saad el Sund. In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Nir Saad al Saaoud, which was translated into Latin as Lucida Fortunæ Fortunarum (rather identic with R.H. Allen), meaning the brightest of luck of lucks. [17] The International Astronomical Union Working Group on Star Names (WGSN) [18] has approved the name Sadalsuud for the primary or 'A' component. [15]
In Chinese, 虚宿 (Xū Xiù), meaning Emptiness (asterism), refers to an asterism consisting of Beta Aquarii and Alpha Equulei. [19] Consequently, the Chinese name for Beta Aquarii itself is 虛宿一 (Xū Xiù Yī, English: the First Star of Emptiness). [20]
Sadalsuud is found in Hindu texts as Kalpeny and, in the context of the ancient Indian system of astronomy, Jyotisha Veda, is located in the 23rd Nakshatra Shravishthā [ broken anchor ], a lunar mansion which is ruled by Eight vasus - the "deities of earthly abundance" . On the Euphrates, Sadalsuud was known as Kakkab Nammax, the Star of Mighty Destiny; that may have given origin to the title of the manzil, as well as to the astrologers' name for it — Fortuna Fortunarum. [21]
β Aquarii is the brightest star in Aquarius with an apparent magnitude of 2.87 [2] and a stellar classification of G0 Ib. [3] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. [22] It has an estimated age of 56 million years; [9] old enough for a star of this mass to evolve into a supergiant. The star has about five or six [9] times the mass of the Sun, but it has expanded to 48 times the Sun's radius. It is most likely fusing helium into carbon in its core, and, with insufficient mass to explode as a supernova, will likely end up as a massive white dwarf comparable to Sirius B. [23] It is emitting roughly 2,000 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,608 K, [8] giving it the characteristic yellow hue of G-type stars. [24]
X-ray emissions from the corona of this star have been detected using the Chandra X-ray Observatory; among the first such detections of X-rays for a G-type supergiant. A secondary X-ray source discovered near Beta Aquarii probably has an extragalactic origin. [12] This star belongs to a group of three intermediate mass stars with a space velocity that is carrying them perpendicular to the plane of the galaxy. The other members of this grouping are Alpha Aquarii and Eta Pegasi. [12]
Component | Magnitude | RA | Dec |
B | 11.0 | 21h 31m 31.9s | −05° 33′ 46″ |
C | 11.6 | 21h 31m 33.0s | −05° 35′ 10″ |
β Aquarii appears as a solitary star to the naked eye, but when viewed with a telescope is seen to have two faint optical companions. The first has an apparent magnitude of 11.0. In 1947, the position angle was observed at 321 degrees with a separation from Beta Aquarii of 35.4 arcseconds. [25] [26] The second star has a magnitude of 11.6. Its position angle is 186 degrees with a separation from Beta Aquarii of 57.2 arcseconds. [25] [26] The brighter star is designated component A of this grouping, while the companions are components B and C, respectively. As of 2008, there is no definitive evidence that the three stars form a ternary star system, [14] and Gaia Data Release 2 shows the two companions to be around twice the distance of β Aquarii. All three stars have very different proper motions. [27] [28]
In the context of older worldviews (i.e. Egyptian, Persian and Islamic mythology), Sadalsuud relates to the rising of the Sun when winter has passed (March) and the season of gentle, continuous rain has begun. [21] Hence the myth of "luck" or "good fortune" was seen as closely aligned with the essence of spring itself, the burgeoning of new life, and by extension agriculture, which in all societies is the very foundation of prosperity or "good fortune". This mythological view of "the luck of the lucks" also belongs to the 22d Manzil (Arabic Lunar Mansion), which included the two stars Xi Aquarii (Bunda) and 46 Capricorni. [21] [a]
β and ξ Aquarii also constitute the Persian lunar mansion Bunda and the similar Coptic mansion Upuineuti, the meaning of which is "the Foundation".
In Chinese mythology, β Aqr alone marks the xiu (Chinese lunar mansion) Heu, Hiu, or Hü, "the Void/Emptiness", anciently Ko, the central one of seven xiu which, taken together, were known as Heung Wu, the Black Warrior, in the northern quarter of the sky. [21] As such, Sadalsuud is an expression of the feminine archetype, the Yin or "Void" (Cosmic Mother), from which, many cultures have believed, creation itself (birth) emanates.
Albireo is a binary star designated Beta Cygni. The International Astronomical Union uses the name "Albireo" specifically for the brightest star in the system. Although designated 'beta', it is fainter than Gamma Cygni, Delta Cygni, and Epsilon Cygni and is the fifth-brightest point of light in the constellation of Cygnus. Appearing to the naked eye to be a single star of magnitude 3, viewing through even a low-magnification telescope resolves it into its two components. The brighter yellow star, itself a very close trinary system, makes a striking colour contrast with its fainter blue companion.
Saiph, designation Kappa Orionis and 53 Orionis, is a blue supergiant star and the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the star at the south-eastern corner. A northern-hemisphere observer facing south would see it at the lower left of Orion, and a southern-hemisphere observer facing north would see it at the upper right. Parallax measurements yield an estimated distance of 650 light-years from the Sun. It is smaller, less luminous but hotter at its surface than Rigel with an apparent visual magnitude of 2.1. The luminosity of this star changes slightly, varying by 0.04 magnitudes.
Castor is the second-brightest object in the zodiac constellation of Gemini. It has the Bayer designation α Geminorum, which is Latinised to Alpha Geminorum and abbreviated Alpha Gem or α Gem. With an apparent visual magnitude of 1.58, it is one of the brightest stars in the night sky. Castor appears singular to the naked eye, but it is actually a sextuple star system organized into three binary pairs. Although it is the 'α' (alpha) member of the constellation, it is half a magnitude fainter than 'β' (beta) Geminorum, Pollux.
Pi Sagittarii is a triple star system in the zodiac constellation of Sagittarius. It has an apparent visual magnitude of +2.89, bright enough to be readily seen with the naked eye. Based upon parallax measurements, it is roughly 510 light-years from the Sun.
Delta Aquarii, officially named Skat, is the third-brightest star in the constellation of Aquarius. The apparent visual magnitude is 3.3, which can be seen with the naked eye. The distance to this star is about 113 light-years based upon parallax measurements, and it has a close companion.
Gamma Aquarii, or γ Aquarii, is a binary star system in the constellation of Aquarius. It has an apparent visual magnitude of 3.849, making it one of the brighter members of the constellation. Based upon parallax measurements taken during the Hipparcos mission, this star is located at a distance of approximately 164 light-years from the Sun. It is drifting closer to the Sun with a radial velocity of −16 km/s. In 1998, Olin J. Eggen included this star as a candidate member of the Hyades Supercluster.
Theta Eridani, Latinized from θ Eridani, is a binary system in the constellation of Eridanus with a combined apparent magnitude of 2.88. Its two components are designated θ1 Eridani, formally named Acamar, and θ2 Eridani. The system's distance from the Sun based on parallax measurements is approximately 165 light-years.
Alpha Aquarii, officially named Sadalmelik, is a single yellow supergiant star in the constellation of Aquarius. The apparent visual magnitude of 2.94 makes this the second-brightest star in Aquarius. Based upon parallax measurements made by the Gaia spacecraft, it is located at a distance of roughly 690 light-years from the Sun. It is drifting further away from the Sun with a radial velocity of 7.5 km/s.
Epsilon Aquarii, Latinized from ε Aquarii, is a binary star in the equatorial zodiac constellation of Aquarius, located near the western constellation border with Capricornus. It has the proper name Albali, now formally recognized by the IAU. It is visible to the naked eye with an apparent visual magnitude of 3.77, and has an absolute magnitude of −0.46. Based upon parallax measurements taken by the Gaia spacecraft, it is located at a distance of approximately 244 light-years (75 pc) from Earth. The star is drifting closer with a radial velocity of −20 km/s.
Xi Aquarii is a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.7. Based upon parallax measurements made during the Hipparcos mission, this system lies at a distance of around 179 light-years from the Sun.
Alpha Crateris, officially named Alkes, is a star in the constellation of Crater. It is a cool giant star about 43.2 parsecs (141 ly) away.
Beta Aquilae, Latinized from β Aquilae, is a triple star system in the equatorial constellation of Aquila. It is visible to the naked eye as a point-like source with an apparent visual magnitude of 3.87. Based on parallax measurements obtained during the Hipparcos mission, it is located at a distance of approximately 44.7 light-years from the Sun. It is drifting closer to the Sun with a radial velocity of −40 km/s.
Iota Andromedae is a single star in the northern constellation of Andromeda. It has the Flamsteed designation 17 Andromedae, while Iota Andromedae is the Bayer designation as Latinized from ι Andromedae. This object is visible to the naked eye at night as a faint, blue-white hued star with an apparent visual magnitude of +4.29. Based upon parallax measurements, it is located approximately 500 light years distant from the Sun.
Zeta Aquarii is the Bayer designation for a triple star system, the central star of the "water jar" asterism in the equatorial constellation of Aquarius. The combined apparent visual magnitude of this system is 3.65, which is readily visible to the naked eye. Parallax measurements yield a distance estimate of around 92 light-years from Earth.
91 Aquarii is a triple star system in the equatorial constellation of Aquarius. It also bears the Bayer designation Psi1 Aquarii. It is visible to the naked eye with an apparent visual magnitude of +4.248. Parallax measurements yield an estimated distance of around 150 light-years from Earth. An extrasolar planet is known to orbit the main star.
Pi Aquarii, Latinized from π Aquarii, is the Bayer designation for a binary star in the equatorial constellation of Aquarius. This system has an apparent visual magnitude of a mean apparent magnitude of +4.57. Based upon parallax measurements, it is located at a distance of roughly 780 light-years from Earth. It is drifting further away with a radial velocity of +4 km/s.
104 Aquarii (abbreviated 104 Aqr) is a star in the equatorial constellation of Aquarius. 104 Aquarii is the Flamsteed designation, although it also bears the Bayer designation A2 Aquarii. Based on an annual parallax shift of only 3.89 ± 0.25 milliarcseconds, the distance to this star is about 840 light-years (260 parsecs). At that range, the brightness of the star in the V-band is reduced by 0.10 magnitudes as a result of extinction caused by intervening gas and dust.
Omicron2 Canis Majoris is a star in the constellation Canis Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It has an apparent visual magnitude of 3.043, making it one of the brighter members of the constellation. Based upon a distance modulus of 10.2, it is about 3,600 light-years from Earth.
46 Capricorni is a solitary star located around 790 light years away from the Sun in the southern constellation of Capricornus, near the northern border with Aquarius. It is visible to the naked eye as a dim, yellow-hued point of light with an apparent visual magnitude of +5.10. 46 Cap is also known by its Bayer designation of c Capricorni, and occasionally as c1 Capricorni to distinguish it from the nearby star c2 Capricorni. It is moving closer to the Earth with a heliocentric radial velocity of −15.5 km/s.