Astronomy: Proxima Centauri

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Source: Wikipedia (CC BY-SA)

Proxima Centauri Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 lig ht-years (1.3 parsecs) away in the southern constellation of Centaurus. Discovered in 1915 by Robert Innes, it is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° southwest of the Alpha Centauri AB pair.

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Why Proxima Centauri matters: Stars are the engines of the cosmos -- they forge the chemical elements, light up galaxies, and create the conditions that make planets and life possible. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years. Its Latin name means the 'nearest star of Centaurus'. Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M☉), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years. Proxima Centauri has two known exoplanets and one candidate exoplanet: Proxima Centauri b, Proxima Centauri d and the disputed Proxima Centauri c. Proxima Centauri b orbits the star at a distance of roughly 0.05 AU (7.5 million km) with an orbital period of approximately 11.2 Earth days. Its estimated mass is at least 1.06 times that of Earth. Proxima b orbits within Proxima Centauri's habitable zone—the range where temperatures are right for liquid water to exist on its surface—but, because Proxima Centauri is a red dwarf and a flare star, the planet's habitability is highly uncertain. A sub-Earth, Proxima Centauri d, roughly 0.028 AU (4.2 million km) away, orbits it every 5.1 days. A candidate sub-Neptune, Proxima Centauri c, roughly 1.5 AU (220 million km) away from Proxima Centauri, orbits it every 1,900 d (5.2 yr).

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Source: Internal

Deep dive: Proxima Centauri Its Latin name means the 'nearest star of Centaurus'. Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M☉), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years. Proxima Centauri has two known exoplanets and one candidate exoplanet: Proxima Centauri b, Proxima Centauri d and the disputed Proxima Centauri c. Proxima Centauri b orbits the star at a distance of roughly 0.05 AU (7.5 million km) with an orbital period of approximately 11.2 Earth days. Its estimated mass is at least 1.06 times that of Earth. Proxima b orbits within Proxima Centauri's habitable zone—the range where temperatures are right for liquid water to exist on its surface—but, because Proxima Centauri is a red dwarf and a flare star, the planet's habitability is highly uncertain. A sub-Earth, Proxima Centauri d, roughly 0.028 AU (4.2 million km) away, orbits it every 5.1 days. A candidate sub-Neptune, Proxima Centauri c, roughly 1.5 AU (220 million km) away from Proxima Centauri, orbits it every 1,900 d (5.2 yr). Source: https://en.wikipedia.org/wiki/Proxima_Centauri (Wikipedia, CC BY-SA)