Gamma Pegasi
Gamma Pegasi, formally named Algenib, is a star in the constellation of Pegasus, located at the southeast corner of the asterism known as the Great Square. The average apparent visual magnitude of +2.84 puts this at fourth place among the brightest stars in the constellation. The distance to this star has been measured using the parallax technique, yielding a value of roughly with a margin of error of 5%.Nomenclature
Gamma Pegasi is the star's Bayer designation. Although it also had the traditional name Algenib, this name was also used for Alpha Persei. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Algenib for this star.
The asterism of γ Pegasi and α Andromedae, in Hindu astronomy, is called Uttara Bhādrapadā or Uttṛṭṭāti. It is the 26th nakshatra. In Chinese, 壁宿, meaning Wall refers to an asterism consisting of γ Pegasi and α Andromedae. Consequently, the Chinese name for γ Pegasi itself is 壁宿一Properties
In 1911, American astronomer Keivin Burns discovered that the radial velocity of Gamma Pegasi varied slightly. This was confirmed in 1953 by American astronomer D. Harold McNamara, who identified it as a Beta Cephei variable. It has a radial pulsation period of 0.15175 days, but also shows the behavior of a slowly pulsating B star with three additional pulsational frequencies. Its magnitude varies between +2.78 and +2.89 over the course of each pulsation cycle.
This is a large star with almost nine times the mass of the Sun and close to five times the Sun's radius. The stellar classification of B2 IV suggests this is a subgiant star that is exhausting the hydrogen at its core and is in the process of evolving away from the main sequence. It is either rotating very slowly with no measurable rotational velocity or else it is being viewed from nearly pole-on. Gamma Pegasi has a total luminosity of 5,840 times that of the Sun, which is being radiated from its outer atmosphere at an effective temperature of more than 21,000 K. At this temperature, the star glows with a blue-white hue.
Despite claims that the star has a magnetic field, this didn't hold up under further observation. Neiner et al. put an upper bound on a dipolar magnetic field strength of about.
