![]() ![]() Mass transfer from the white dwarf progenitor onto Regulus accounts for any discrepancies between the star’s age and its mass, temperature, and luminosity.Īlpha Leonis system, image credit: Pablo Carlos Budassi (CC BY-SA 4.0) ![]() However, it would have taken at least a billion years for the white dwarf to form. Before it became a white dwarf, the companion is believed to have transferred a lot of its mass onto the other star through gravitational interaction, speeding up the primary component’s rotation rate to what it is now.īefore the discovery of the white dwarf, Regulus was believed to be a much younger star, with an estimated age between 50 and 100 million years. The primary component was once the smaller of the two stars. The two components complete an orbit every 40.11 days. The companion is believed to be a white dwarf. The main component in the Regulus A system is orbited by a companion with at least 0.3 solar masses. The poles are said to be “gravity brightened,” while the equator is “gravity darkened.” The poles of Regulus are five times brighter than the equator. Due to the star’s oblate shape, its poles are closer to the centre of mass and have a higher effective temperature and therefore brightness, while the equatorial region is cooler and less bright. ![]() As a result, the star is emitting polarized light.Īlong with the brighter Vega, Altair, and Achernar, Regulus is one of the brightest and best-known examples of gravity darkening. Regulus completes a rotation in only 15.9 hours and its equatorial rotational velocity is 96.5 percent of its breakup velocity. The equatorial diameter of Regulus is 32 percent larger than its polar diameter. It has an estimated age of at least a billion years.Īs a result of Regulus’ fast rotation, the star’s shape has been distorted into a highly oblate spheroid. The star is a very fast spinner, with a projected rotational velocity of 318 km/s at the equator. With a surface temperature of 11,668 K, it shines with 316.2 solar luminosities. Regulus has a mass 3.8 times that of the Sun and a radius 4.35 times solar. It is classified as a high proper motion star. It is almost finished fusing hydrogen into helium in its core. Regulus is also an evolutionary subgiant. The primary component, formally known as Regulus, has been given the stellar classification B8 IVn, with the luminosity class of a subgiant star. DSS is one of the programs of STScI (Space Telescope Science Institute). Image created using the Aladin Sky Atlas software from the Strasbourg Astronomical Data Center and DSS (Digitized Sky Survey) data. Regulus A is a spectroscopic binary system consisting of a blue-white main sequence star and a dim companion that has not yet been seen directly. The main components are designated as Alpha Leonis (Regulus) A, B, and C. ![]() Regulus appears as a single star to the unaided eye, but it is in fact a quadruple star system consisting of two pairs of stars and possibly more components. The star is also one of the vertices of the Spring Triangle, a conspicuous asterism visible in the evening sky during the northern hemisphere spring. Regulus sits at the base of the Sickle, marking the lion’s heart. Regulus is part of a relatively bright asterism known as the Sickle of Leo, which outlines the celestial lion’s head, mane, and shoulders. With a combined apparent magnitude of 1.40, it is the brightest star in Leo and the 21st brightest star in the sky. Regulus, Alpha Leonis (α Leo), is the primary component in a multiple-star system located 79.3 light-years away in the constellation Leo. ![]()
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