Proxima Centauri

From Academic Kids

The red dwarf star Proxima Centauri, part of the Alpha Centauri star system, is the nearest star to Earth, other than the Sun. As the name suggests, it is located in the constellation of Centaurus. Proxima Centauri was discovered in 1915 by Robert Innes while he was Director of the Union Observatory in Johannesburg, South Africa. The star is also known as Alpha Centauri C, V645 Centauri, Gl 551, LHS 49, and GCTP 3278.00.



Red dwarfs in general are far too weak to be observable with the naked eye, and Proxima Centauri is no exception. It has an apparent magnitude of 11 while its absolute magnitude is a very weak 15.53. Seen from Alpha Centauri A or B, Proxima would be a 4.5 magnitude star.

Based on the parallax of 772.33  2.42 milliarcseconds measured by Hipparcos, Proxima Centauri is roughly 4.22 light years from Earth, or 270,000 times more distant than the Sun. Its closest neighbours are Alpha Centauri A and B (at 0.21 light years), the Sun, and Barnard's Star (at 6.55 light years). From Earth's vantage point, Proxima is separated by 2° from Alpha Centauri, or 4 times the angular diameter of the full Moon.

In 2002, VLTI used optical interferometry to measure an angular diameter of 1.02  0.08 milliarcsec for Proxima Centauri. Knowing its distance, the actual diameter can be determined to be about 1/7 that of the Sun, or 1.5 times that of Jupiter. Its mass is also about 1/7 that of the Sun, or 150 times that of Jupiter.

At a distance to Alpha Centauri of just 1/20th the distance to the Sun, Proxima may actually be in orbit about Alpha, with an orbital period on the order of 500,000 years or more. For this reason, Proxima is sometimes referred to as Alpha Centauri C. However, it is not clear if it really is in orbit, although the association is unlikely to be entirely accidental as it shares approximately the same motion through space as the larger star system.

Traveling to Proxima Centauri

Proxima Centauri has been suggested as a logical first destination for interstellar travel, although as a flare star it would not be particularly hospitable. The current standard spaceship, the Space Shuttle, travels in orbit at 7.8 km/s. At that speed, it would take 160,000 years to reach Proxima. The fastest man-made spacecraft, the Helios II deep space probe, has set a speed record of 70.2 km/s. Even at that speed, the journey to Proxima Centauri would take 18,000 years. The proposed VASIMR propulsion system, possibly able to achieve speeds up to 300 km/s, would shorten the journey to a "mere" 4,200 years —still firmly beyond the current lifespan of both man and machine. It follows that interstellar travel would require radically new ideas to become feasible. Requiring us to use faster, larger and stronger spacecraft.

See also

External links

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