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Proxima Centauri

2007 Schools Wikipedia Selection. Related subjects: Space (Astronomy)

   CAPTION: Proxima Centauri

                             Observation data
   Epoch J2000
   Constellation             Centaurus
   Right ascension           14h 29m 43.0s
   Declination               -62° 40' 46"
   Apparent magnitude (V)    11.05
                             Characteristics
   Spectral type             M5.5 V
   B-V colour index          1.90
   U-B colour index          1.49
   Variable type             Flare star
                                Astrometry
   Radial velocity (R[v])    -20.3 km/s
   Proper motion (μ)         RA: -3775.64 mas/ yr
                             Dec.: 768.16 mas/ yr
   Parallax (π)              771.99 ± 2.25 mas
   Distance                  4.22 ± 0.01 ly
                             (1.295 ± 0.004 pc)
   Absolute magnitude (M[V]) 15.49
                                 Details
   Mass                      0.12 M[☉]
   Radius                    0.15 R[☉]
   Luminosity                5-12 × 10^-5 L[☉]
   Temperature               2,670 K
   Metallicity               10%
   Rotation                  30-33 days
   Age                       estimated 1 × 10^9 years
                            Other designations
   α Centauri C, V645 Centauri, GCTP 3278.00, GJ 551, LHS 49, LFT 1110,
   LTT 5721, HIP 70890.

   The red dwarf star Proxima Centauri, part of the Alpha Centauri star
   system, is the nearest star to our Sun. As the name suggests, it is
   located in the constellation of Centaurus. Proxima Centauri was
   discovered to share the same proper motion as Alpha Centauri in 1915 by
   Robert Innes while he was Director of the Union Observatory in
   Johannesburg, South Africa. It was Innes who suggested the name
   Proxima. In 1917 at the Royal Observatory, Cape of Good Hope, the Dutch
   astronomer J. Voûte measured the trigonometric parallax and determined
   that Proxima was indeed at the same distance as Alpha Centauri, and
   hence was also the faintest star known at the time.

Characteristics

   Red dwarfs in general are far too faint 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 dim 15.5. Seen from Alpha
   Centauri A or B, Proxima would be a 4.5 magnitude star.

   Based on the parallax of 772.3 ± 2.4 milliarcseconds measured by
   Hipparcos (and the more precise parallax determined using the Fine
   Guidance Sensors on the Hubble Space Telescope of 768.7 ± 0.3
   milliarcseconds), Proxima Centauri is roughly 4.2 light years from
   Earth, or 270,000 times more distant than the Sun. Its closest
   neighbors 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 of Proxima Centauri's
   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 possible that it may not actually be 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 .

   Proxima, along with Alpha Centauri A and B, are among the "Tier 1"
   target stars for NASA's Space Interferometry Mission (SIM). SIM will be
   able to detect planets as small as three Earth-masses within two
   Astronomical Units of a "Tier 1" target. Due to Proxima's small mass
   and distance, SIM would be able to detect even smaller planets around
   this star, should they exist.

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 significant development
   of radical ideas to become feasible, such as hypothetical generation
   ships, laser-pushed solar sails, nuclear fusion powered Bussard
   ramjets, nuclear pulse drives or warp drives.

Proxima Centauri in popular culture

Trivia

     * "Proxima Centauri" is the title of a song by the band At the
       Drive-In.
     * "Proxima Centauri" is the title of a software product by the
       company Proxima Technology.

Fiction

          See Proxima Centauri in fiction.

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   with only minor checks and changes (see www.wikipedia.org for details
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