Dschubba (Delta Scorpii)

Dschubba (Delta Scorpii) is the fifth brightest star in the constellation Scorpius and the middle star of three that make the head of the Scorpion. Its name stems from an Arabic phrase meaning "the forehead" ("jabhat") of the Scorpion, which was originally applied to the whole line – Graffias, Dschubba, and the somewhat fainter Pi Sco. Dschubba is a multiple star system. The main component, a hot B star, is accompanied by a cooler B-type companion about 10 times fainter, the two separated by roughly Mercury's distance from the Sun and taking 20 days to complete an orbit. A third companion, two-thirds as bright as the dominant star, lies farther away, at least at Saturn's distance, and takes at least a decade to make the round trip. At a minimum of double this distance lies yet another, fainter star. With masses that range from 6 to 12 times that of the Sun, all are probably still on the main sequence. Dschubba is part of an association of O and B stars that includes both Graffias and Antares, all of which were born within the same complex of interstellar gas and dust. Although fairly close to us, there is so much dust in the line of sight that the stars of Dschubba are dimmed by about 50%.


visual magnitude 2.29
absolute magnitude -3.16
spectral type B0.3IV
luminosity 14,000 Lsun
radius 5 Rsun
distance 402 light-years
position R.A. 16h 00m 20s,
Dec. -22 37' 18"