About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 68. Chapters: 51 Pegasi, 51 Pegasi b, 85 Pegasi, Abell 2390, Alpha Pegasi, BD+14 4559, BD+14 4559 b, Beta Pegasi, BX442, Einstein Cross, Epsilon Pegasi, Gamma Pegasi, HAT-P-8, HAT-P-8b, HD 209458, HD 209458 b, HD 210702, HD 210702 b, HD 218133, HD 218155, HD 219828, HD 219828 b, HR 8799, HR 8799 b, HR 8799 c, HR 8799 d, HR 8799 e, Huchra's lens, II Pegasi, IK Pegasi, IM Pegasi, Iota Pegasi, Kappa Pegasi, Lambda Pegasi, List of stars in Pegasus, Messier 15, Mu Pegasi, NGC 1, NGC 14, NGC 15, NGC 16, NGC 18, NGC 2, NGC 22, NGC 23, NGC 32, NGC 7217, NGC 7317, NGC 7318, NGC 7319, NGC 7320c, NGC 7331, NGC 7331 Group, NGC 7332, NGC 7479, NGC 7742, NGC 7752 and NGC 7753, NGC 7777, NGC 7814, NGC 8, Pease 1, Pegasus Dwarf Irregular Galaxy, Pegasus Dwarf Spheroidal Galaxy, SN 1990U, S Pegasi, Tau Pegasi, Theta Pegasi, V391 Pegasi, V391 Pegasi b, WASP-10, WASP-10b, WISEPC J215751.38+265931.4, WISEPC J221354.69+091139.4, WISEPC J222623.05+044003.9, WISE J234228.98+085620.2, WISE J235716.49+122741.8, Zeta Pegasi. Excerpt: IK Pegasi (or HR 8210) is a binary star system in the constellation Pegasus. It is just luminous enough to be seen with the unaided eye, at a distance of about 150 light years from the Solar System. The primary (IK Pegasi A) is a A-type main-sequence star that displays minor pulsations in luminosity. It is categorized as a Delta Scuti variable star and it has a periodic cycle of luminosity variation that repeats itself about 22.9 times per day. Its companion (IK Pegasi B) is a massive white dwarf a star that has evolved past the main sequence and is no longer generating energy through nuclear fusion. They orbit each other every 21.7 days with an average separation of about 31 million kilometres, or 19 million miles, or 0.21 astronomical units (AU). This is smaller than the orbit of Mercury around the Sun. IK Pegasi B is the nearest known supernova progenitor candidate. When the primary begins to evolve into a red giant, it is expected to grow to a radius where the white dwarf can accrete matter from the expanded gaseous envelope. When the white dwarf approaches the Chandrasekhar limit of 1.38 solar masses, it may explode as a Type Ia supernova. This star system was catalogued in the 1862 Bonner Durchmusterung ("Bonn astrometric Survey") as BD +18 4794B. It later appeared in Pickering's 1908 Harvard Revised Photometry Catalogue as HR 8210. The designation "IK Pegasi" follows the expanded form of the variable star nomenclature introduced by Friedrich W. Argelander. Examination of the spectrographic features of this star showed the characteristic absorption line shift of a binary star system. This shift is created when their orbit carries the member stars toward and then away from the observer, producing a doppler shift in the wavelength of the line features. The measurement of this shift allows astronomers to determine the relative orbital velocity of at least one of the stars even though they are unable to resolve the individual components. In 1927, the Canadian astr
