Alpha Delphini

α Delphini (Latinised to Alpha Delphini) is the system's Bayer designation. The designations of the six constituents as Alpha Delphini A to F, and those of ''A's components - Alpha Delphini Aa and Ab'' - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). The primary star's components Aa, Ab1, and Ab2 are also sometimes referred to as A, Ba, and Bb respectively, given that the outer pair have been resolved. It approved the name Sualocin for the component Alpha Delphini Aa on 12 September 2016, and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning Good Gourd, refers to an asterism consisting of Alpha Delphini, Gamma2 Delphini, Delta Delphini, Beta Delphini and Zeta Delphini. Consequently, the Chinese name for Alpha Delphini itself is (, ). In Hindu astronomy, the star corresponded to one of the nakshatras named Dhanishta. == Properties ==

Alpha Delphini A is a spectroscopic binary star which has now been resolved using speckle interferometry. The components are separated by and have a 17-year orbit. Alpha Delphini Aa has a spectral type of B9IV. It is a subgiant that has begun to evolve away from the main sequence, is about 3.8 times as massive as the sun and about twice as hot. The spectral type of the secondary star cannot be determined as it is too close and too faint compared to the primary, but it has been shown to itself be a binary star with an orbit of 30 days. Spectral lines showing 30-day radial velocity changes are likely to belong to the faintest component, expected from its mass to be an F-type star. Then the more massive star of the inner pair is likely to be an A-type dwarf, possibly not detected in the spectral because rapid rotation blurs its absorption lines. The five faint companions have visual magnitudes around 11th to 13th magnitude and separations of 35" to 72". They all show motion relative to Alpha Delphini A, and have much smaller parallaxes. ==References==