Mu Boötis, Latinized from μ Boötis, consists of a pair of double stars in the northern constellation of Boötes, 120 light-years from the Sun.
Mu Boötis had the traditional name Alkalurops /ælkəˈljʊərɒps/ , although the International Astronomical Union now regards that name as only applying to μ1 Boötis. [11]
The primary pair, component A, is designated μ1 Boötis and the two components an angular separation of 0.08″.[ citation needed ]
The secondary, consisting of components BC, is designated μ2 Boötis and they have a separation of 2.2″. The two double star systems are separated by 107″, with matching parallaxes and proper motions, suggesting they form a system. However, components BC have a different chemical composition compared to the A pair, indicating this may instead be a close encounter between two binary systems. [6]
μ Boötis (Latinised to Mu Boötis) is the star's Bayer designation. It also bears the Flamsteed designation 51 Boötis.
The system's traditional name Alkalurops is from the Greek καλαύροψ kalaurops "a herdsman's crook or staff", with the Arabic prefix attached. [12] It has also been known as Inkalunis (from the Alfonsine tables), Clava (Latin 'the club') and Venabulum (Latin 'a hunting spear'). [13] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [14] to catalogue and standardize proper names for stars. The WGSN approved the name Alkalurops for μ¹ Boötis on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names. [11]
It is known as 七公六, Qī Gōng liù (the Sixth Star of the Seven Excellencies) in Chinese. [15]
μ1 Boötis is a yellow-white F-type subgiant with an apparent magnitude of +4.31.
Separated from its brighter companion by 108 arcseconds in the sky is the binary star μ2 Boötis, which has a combined spectral type of G1V and a combined brightness of +6.51 magnitudes. The components of μ2 Boötis have apparent magnitudes of +7.2 and +7.8 and are separated by 2.2 arcseconds.[ citation needed ] They complete one orbit about their common centre of mass every 260 years.
Mu Draconis is a multiple star system near the head of the constellation of Draco. With a combined magnitude of 4.92, it is visible to the naked eye. Based on parallax estimates by the Hipparcos spacecraft, it is located approximately 89 light-years from the Sun.
Gamma Geminorum, formally named Alhena, is the third-brightest object in the constellation of Gemini. It has an apparent visual magnitude of 1.9, making it easily visible to the naked eye even in urban regions. Based upon parallax measurements with the Hipparcos satellite, it is located at a distance of roughly 109 light-years from the Sun.
Epsilon Boötis, officially named Izar, is a binary star in the northern constellation of Boötes. The star system can be viewed with the unaided eye at night, but resolving the pair with a small telescope is challenging; an aperture of 76 mm (3.0 in) or greater is required.
Sigma Scorpii, is a multiple star system in the constellation of Scorpius, located near the red supergiant Antares, which outshines it. This system has a combined apparent visual magnitude of +2.88, making it one of the brighter members of the constellation. Based upon parallax measurements made during the Hipparcos mission, the distance to Sigma Scorpii is roughly 696 light-years (214 parsecs). North et al. (2007) computed a more accurate estimate of 568+75
−59 light years.
Zeta Sagittarii is a triple star system and the third-brightest star in the constellation of Sagittarius. Based upon parallax measurements, it is about 88 light-years from the Sun.
Nu¹ Sagittarii is a triple star system about 1,100 light-years from Earth. Its three components are designated Nu¹ Sagittarii A, B and C. A and B themselves form a spectroscopic binary. The system is 0.11 degree north of the ecliptic.
Iota Virginis is a binary star in the constellation of Virgo. Its apparent magnitude is 4.08. Based on its parallax, it is assumed to be relatively nearby, at 72.5 light-years.
Mu Ursae Majoris, formally named Tania Australis, is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 places it among the brighter members of the constellation. Parallax measurements give an estimated distance of roughly 230 light-years from the Sun, with a margin of error of 4%.
Iota Ursae Majoris, also named Talitha, is a star system in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of 3.14, making it visible to the naked eye and placing it among the brighter members of this constellation. Based upon parallax measurements, it is located at a distance of 47.3 light-years from the Sun.
Kappa Ursae Majoris is a binary star in the constellation of Ursa Major. With a combined apparent magnitude of +3.60, the system is approximately 358 light-years from Earth.
Mu Pegasi or μ Pegasi, formally named Sadalbari, is a star in the northern constellation of Pegasus. The apparent visual magnitude of this star is 3.5, which is bright enough to be seen with the naked eye even on a moonlit night. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 106 light-years from the Sun.
Theta Aurigae is a binary star in the constellation of Auriga. Based upon parallax measurements, the distance to this system is about 166 light-years.
Gamma Boötis, Latinised from γ Boötis, is a binary star system in the northern constellation of Boötes the herdsman, forming the left shoulder of this asterism. The primary component has the proper name Seginus, the traditional name of the Gamma Bootis system. It has a white hue and is visible to the naked eye with a typical apparent visual magnitude of +3.03. Based on parallax measurements obtained during the Hipparcos mission, it is located at a distance of approximately 85 light-years from the Sun, but is drifting closer with a radial velocity of −32 km/s.
Theta Boötis, Latinized from θ Boötis, is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism. It has the traditional name Asellus Primus and the Flamsteed designation 23 Boötis. Faintly visible to the naked eye, this star has a yellow-white hue with an apparent visual magnitude of 4.05. It is located at a distance of 47 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −10.6 km/s.
Lambda Boötis, also named Xuange, is a star in the northern constellation of Boötes. Based on parallax measurements, it is approximately 99 light-years from the Sun.
Xi Cancri is a spectroscopic binary star system in the zodiac constellation of Cancer. It is visible to the naked eye with an apparent visual magnitude of +5.15. Based upon parallax measurements obtained during the Hipparcos mission, it is roughly 370 light-years distant from the Sun.
Xi Draconis is a double or binary star in the northern circumpolar constellation of Draco. It has an apparent visual magnitude of 3.75. Based upon parallax measurements, it is located at a distance of 112.5 light-years from the Sun. At this distance, the apparent magnitude is diminished by 0.03 from extinction caused by intervening gas and dust.
Nu Capricorni or ν Capricorni is a binary star system in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +4.76.
Delta Cygni is a binary star of a combined third-magnitude in the constellation of Cygnus. It is also part of the Northern Cross asterism whose brightest star is Deneb. Based upon parallax measurements obtained during the Hipparcos mission, Delta Cygni is located roughly 165 light-years distant from the Sun.
Zeta Piscium is a quintuple star system in the zodiac constellation of Pisces. Based upon parallax measurements obtained during the Hipparcos mission, it is located roughly 170 light-years distant from the Sun.