Alpha Centauri – As observed in nature and culture – Our Closest Neighbor Part II

The quest to explore beyond our home planet has inspired some of the most memorable moments from the latter part of the 20th century. Take this for instance. As of 2015 for every person who has seen the ocean floor of the Mariana Trench, four have walked on the surface of the moon. Let’s learn about the nearest star system to us.

Part 1: The brightest star in the day sky

Part 3: Discovery and further study of Alpha Centauri

Part 4: The Proxima Puzzle, Stellar Proximities, and Earthly Purview

Alpha Centauri system is believed to be a binary star system. They are termed Alpha Centauri A and Alpha Centauri B. Proxima Centauri, the actual closest star to the Sun might have a gravitational relationship with Alpha Centauri system. It is a red dwarf star, which is the state in which a majority of stars are present in our galaxy. Red dwarfs outnumber Sun-like stars in the ration of 1:8 to 1:10. Of the 200 billion stars in the Milky Way galaxy, Alpha Centauri system is the closest, at about 28 million solar diameters away. This distance is getting closer but is expected to be far enough to avoid any possible gravitational interactions.

Alpha Centauri system became our closest neighbor around 50,000 years ago and will remain so for another 72,000 years. Eventually, the star system will pass away to such a distance that it will be impossible to view from the naked eye, here on earth. Seen from Alpha Centauri, our Sun will appear as a part of the constellation of Cassiopeia. It will outshine the star Schedar (a.k.a. Alpha Cassiopeia) which appears as the brightest star when viewed from Earth.

A binary star system

Alpha Cen A and Alpha Cen B orbit around a common center, each revolution taking 80 earth years.  Being an elliptical path that the stars take, the closest they come to each other is at a distance of 11.3 AU while at the farthest they are 35.7 AU away from each other. The stars have completed about 75 million orbits by now, having started a billion years before Sun and solar system came into existence.

Binary systems, as well as stars with a few planets around them, travel in a serpentine-like wavy path as opposed to a straight line that many of the single stars tend to move on. Proxima Centauri is different in nature to both Alpha Centauri A and B. Also, it is smaller and dimmer than the two stars. It was discovered by Robert Innes in 1915.

There is a 1 in 57,000 chance that Proxima Centauri would be located so close to Alpha Centauri. It is still a mystery whether they form a triple-system or just an odd-pairing of Proxima with the binary Alpha Centauri system. There are 88 constellations that are officially recognized. Centaurus, the home constellation of the Alpha Centauri system is the 9th largest among them.

Centaur in mythology and literature

Centaur is a half-man, half-horse creature in Greek mythology. In literature, they are represented as generally wise but can get fierce when necessary. The Chronicles of Narnia and Harry Potter series portray them similarly. The constellation is taught to be representing the wisest of the centaurs, named Chiron. The son of King Cronus and Philyra, Chiron is described as an expert in medicine, music, and hunting. Being an immortal, it is believed that Chiron was placed among the stars when he had to be removed from the mortal world, by Zeus. There is another Centaur in the skies, Sagittarius.

Among the Maoris of New Zealand, Alpha Centauri represents the anchor of the ship of the Great Waka (the Milky Way). Alpha Centauri and Beta Centauri represented the eyes of the mother Ilama, for the ancient Incas. In Chinese mythology, Alpha Centauri represented the fifth column of the library house, part of the Horn mansion.

Being the third brightest stellar object in the night sky, Alpha Centauri misses out on many occasions. The ancient Egyptians gave high places for Sirius and Canopus, the brighter stars. Even the national flags of Brazil, New Zealand, and Australia, having inspired by star systems, ignore Alpha Centauri.  As the earth goes through the precession of its spin axis, every 26,000 years, over time, the relative placement of the constellations (in the sky) as well as those of the stars within them (as perceived from earth) also change. Hence, when the ancient astronomers watched the Centaurus, it would have appeared to have a more aggressive stance.

Notes:

  • Beech, M. (2015).Alpha Centauri. 1st ed. Springer International Publishing. [Minor planet (12343) Martin Beech has been named in recognition of his contributions to meteor physics.]

Paperback version

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  • The nomenclature used properly should be (α – Alpha, ß – Beta). It must be noted that the use of actual words than Greek letters is aimed to make reading easier.
  • Periastron is the point at which the stars of a binary system are closest. Apastron is the point at which the stars of a binary system are farthest apart. Source: Dictionary.com
  • Centaurs may best be explained as the creation of a folktale in which wild inhabitants of the mountains and savage spirits of the forests were combined in half-human, half-animal form. In early art they were portrayed as human beings in front, with the body and hind legs of a horse attached to the back; later, they were men only as far as the waist. They fought using rough branches of trees as weapons. Source: Encyclopedia Britannica

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