Astrophysics 101: Proxima Centauri Traditional Geocache
Astrophysics 101: Proxima Centauri
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Difficulty:
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Terrain:
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Size: 
(small)
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This is the third in a series of caches intended to display the relative sizes of stellar (i.e., star like) objects. The intended scale is 1 kilometer = 1 inch. GC15DXX (The Crab Pulsar) serves as the center reference point for this series of caches.
Proxima Centauri is a red dwarf main sequence star that is a member of the Alpha Centauri star system (The closest stellar system to Earth). The two larger stars in this system, Alpha Centaui A and B, are both approximately the size of the sun, orbit one another at a separation of about 11 Astronomical Units (11 AUs, roughly the distance between the Sun and Saturn), and are about 4.33 Light Years (LY) from the solar system. Proxima Centauri is only weakly bound to these two stars, orbits the central pair at a distance of 13,000 AU (0.21 LY), and is located about 4.22 LY from the solar system. Being the closest star in closest star system, Proxima Centauri has the honor of being the star nearest to the solar system. Hence the name 'Proxima'.
Red Dwarf stars are low mass, low luminosity main sequence stars. Like all main sequence stars, they have a hydrogen to helium fusion reaction proceeding in their cores. Because of their low masses, red dwarfs have relatively low central densities and temperatures resulting in low fusion rates. This low energy production rate results in a low luminosity star with an extremely long lifetime (In general, the smaller the star, the less luminous and longer lived it will be). Red dwarfs are the most common star type in the Galaxy, at least in the neighborhood of the Sun.
Proxima is a mid-size red dwarf with a mass of 0.123 Solar masses and a radius about equal to 0.145 Solar radii (~ 100,000 kilometers or 1.4 Jupiter Radii). On the scale of this series (1 inch = 1 kilometer), the distance from this cache to the reference point GC15DXX (~1.6 miles) is the equivalent of the radius of Proxima Centauri. Note the order of magnitude increase in size compared to the neutron star (~ 1 foot scale radius) and the white dwarf (~ 0.10 mile scale radius). The heat energy resulting from the fusion reaction in the core of a main sequence star provides pressure support against gravitational collapse at sizes far larger than is possible for stellar remnants with no internal energy sources.
It should be noted that based on Stellar Evolution Theory, Proxima Centauri has a projected lifetime of 1900 billion years (Compared to the present estimated age of the Universe of 13 billion years). The lights won't be going out at Proxima any time soon.
Additional Hints
(Decrypt)
Greerfgvny bowrpg jvgu zhygvcyr gehaxf.