IK Pegasi
IK Pegasi is a binary star system in the constellation Pegasus. It is just luminous enough to be seen with the unaided eye. The primary star is an A-type main-sequence star that displays minor pulsations in luminosity. Its companion is a massive white dwarf that has evolved past the main sequence.
About IK Pegasi in brief
IK Pegasi 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 154 light years from the Solar System. The primary star is an A-type main-sequence star that displays minor pulsations in luminosity. Its companion 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. IK Pegasi B is the nearest known supernova progenitor candidate. When the white dwarf approaches the Chandrasekhar limit of 1. 4 solar masses, it may explode as a Type Ia supernova. The inclination of this system’s orbital plane is believed to be nearly edge-on as seen from the Earth. If so it may be possible to observe an eclipse. A part of the star’s outer atmosphere becomes optically thick due to partial ionization of certain elements. This results in an increase in temperature that causes the atmosphere to expand in temperature. The atmosphere becomes less ionized and loses energy, causing it to cool back down. The star’s luminosity variation repeats itself about 22. 9 times per day. The Hertzsprung-Russell diagram is a plot of luminosity versus a color index for a set of stars.
Ik Pegasi A is currently a main sequence star—a grouping of core hydrogen-fusing stars based on their position on the HR diagram. However, I lies in a narrow vertical band of the HR band that is known as a coherent band. Stars in this band oscillate in this manner in a known manner, resulting in periodic variations in the star’s luminosity in the periodic cycle of the Delta Scuti variable star. This is a process called the κ-mechanism. The stars in this region are known to optically optically ionize and lose energy from the atmosphere, causing the outer atmosphere to shrink back down again. This process is known to be known as the Κ-mechnism and it is the cause of the instability in the stars in the HR group. It can also be seen in the Bayer Catalog of stars, which is used to describe the instability of stars that lie in a nearly vertical band in this particular region of the diagram. It was catalogued in the 1862 Bonner Durchmusterung as BD +18°4794B. It later appeared in Pickering’s 1908 Harvard Revised Photometry Catalogue as HR 8210. The designation follows the expanded form of the variable star nomenclature introduced by Friedrich W. Argelander. In 1927, the Canadian astronomer William E. Harper used this technique to measure the period of this single-line spectroscopic binary and determined it to be 21.724 days.
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This page is based on the article IK Pegasi published in Wikipedia (as of Dec. 06, 2020) and was automatically summarized using artificial intelligence.
