28 Cygni

28 Cygni is a single star in the northern constellation of Cygnus. It is a faint blue-white hued star but visible to the naked eye with an apparent visual magnitude of 4.93. The distance to 28 Cyg, as estimated from its annual parallax shift of , is around 620 light years. It has an absolute magnitude of −2.56, which means that if the star were just away it would be brighter than Sirius, the brightest star in the night sky.
This is a B-type main-sequence star with a stellar classification of B2.5 V, per Lesh (1968). Slettebak (1982) found a class of B2 IV(e), which would suggest this is a more evolved subgiant star. It is a Be star, which means the spectrum displays emission lines due a disk of ejected gas in a Keplerian orbit around the star. The star displays short-term variability with two or more periods, and is classified as an SX Arietis variable by Samus et al. (2017). It is spinning rapidly with a projected rotational velocity of 320 km/s; estimated at round 80% of the critical rotation rate. This is giving the star an oblate shape with an equatorial bulge out to 6.5 times the Sun's radius, compared to 5.7 at the poles.