Seginus is a white bright giant star of the spectral type A7 IV+(n). ![]() It has an apparent magnitude of 3.03 and lies 86.8 light years away. Seginus is the brighter of the two components of the Gamma Boötis system. The name Nekkar comes from the Arabic name for the constellation Boötes, Al Baḳḳār (the Herdsman). This was the first such detection on a star in its class and may be explained by an unseen red dwarf companion. An X-ray flare was detected on the star in 1993. Its estimated age is between 240 and 251 million years. It has a mass of 3.4 solar masses and is between 170 and 194 times more luminous than the Sun. It is twice the size of Delta Boötis, with a radius 21.5 times that of the Sun. The star shines at magnitude 3.488 from a distance of 225 light years. It marks the head of the celestial Herdsman. It has the stellar classification G8IIIa. Nekkar, Beta Boötis, is another yellow giant. The primary component has a radius 10.5 times that of the Sun and is 53.7 times more luminous than our star. The brighter component, the giant, has an apparent magnitude of 3.482, while the dwarf is considerably fainter and invisible to the unaided eye at magnitude of 7.81. It consists of a pair of yellow-white stars, one a giant (G8 III) and the other still on the main sequence (G0 V). The Kite in Boötes, image: Till Credner (CC BY-SA 3.0)ĭelta Boötis, traditionally (but not formally) known as Princeps, is another binary system. The stars take at least a thousand years to complete an orbit. The two stars are separated by 2.852 ± 0.014 arcseconds, which corresponds to a physical separation of 185 light years. Izar’s companion is a white main sequence star with the stellar classification A2 V. The star’s traditional name, Izar, comes from the Arabic word for “veil.” It is not, however, massive enough to go out as a supernova and will instead meet its end as a faint white dwarf. While Arcturus follows its evolutionary path at a more leisurely pace, Izar has evolved faster due to its high mass and will therefore have a shorter life. Even though it appears similar to Arcturus, Izar is much younger, with an estimated age of only 37.4 million years. With a surface temperature of 4,500 K, it shines with 501 solar luminosities. The brighter component is an evolved orange giant or bright giant of the spectral type K0 II-III with a mass 4.6 times that of the Sun and a radius 33 times solar. ![]() The system is a popular target for small telescopes. Izar is the primary component in a binary system located about 203 light years away. Izar, Epsilon Boötis, is the second brightest star in Boötes, with an apparent magnitude of 2.37. The name Arcturus comes from the Greek Ἀρκτοῦρος, meaning “guardian of the bear.” The bear in question is Ursa Major. The Spring Triangle and the Great Diamond of Virgo, image: Wikisky It forms the Spring Triangle with Denebola (or alternatively Regulus) in Leo and Spica in Virgo, and the Great Diamond with Spica, Denebola and Cor Caroli, the brightest star in the constellation Canes Venatici. With a surface temperature of 4,286 K, it is 170 times more luminous than the Sun.Īrcturus is part of two other prominent asterisms. As it evolved away from the main sequence, Arcturus has expanded to a size of 25.4 solar radii. It has about the same mass as the Sun (1.08 solar masses) and is older than our star, with an estimated age of 7.1 billion years. The latter two are invisible from mid-northern latitudes, which makes Arcturus the second brightest star seen from most of Europe and North America.Īrcturus is a red giant with the stellar classification K0 III. With an apparent magnitude of -0.05, it is only fainter than Sirius, Canopus, and Alpha Centauri. Arcturus is one of our nearest bright neighbours, located only 36.7 light years away. The brightest of these is the constellation’s luminary Arcturus, the brightest star in the northern celestial hemisphere and fourth brightest star in the sky. The Kite is formed mostly of giant and subgiant stars.
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