I want to live in Alpha Centauri, boys!!

Alpha Centauri A

Rigil Kentaurus ("Foot of the Centaur" in Arabic) is the fourth brightest star in the night sky as well as the brightest star in Constellation Centaurus. Like Sol, it is a yellow-orange main sequence dwarf star of spectral and luminosity type G2 V. It has about 1.105 ± 0.007 times Sol's mass (Guedes et al, 2008; and Thévenin et al, 2002) and 1.23 its diameter (ESO science release; and Demarque et al, 1986), and is about 52 to 60 percent brighter than Sol (ESO science release; and Demarque et al, 1986).

NASA



Alpha Centauri A is a yellow-orange star
like our Sun, Sol. (See a 2MASS Survey
image of Alpha Centauri A and B from
the NASA Star and Exoplanet Database.)

Without consideration of interior seismic constraints, Star A (and B) has been estimated to be older than Sol, from 4.85 billion years in age (ESO) to around 7.6 (+/- around 10 percent) billion years or more -- or 6.8 billion years if it does not have a convective core (Guenther and Demarque, 2000). Recent recent interior modeling with seismic constraints, however, suggest that Stars A and B could be 5.6 to 5.9 billion years old (Mutlu Yildiz, 2007). Since Alpha Centauri A is very similar to our own Sun, however, many speculate whether it might contain planets that harbor life. Useful star catalogue numbers and designations for Alpha Centauri A include: Alp or Alf Cen A, Alp1 Cen, HR 5459, Gl 559 A, Hip 71683, HD 128620, CP(D)-60 5483, SAO 252838, FK5 538, and LHS 50.

Alpha Centauri B

© Torben Krogh & Mogens Winther,
(Amtsgymnasiet and EUC Syd Gallery,
student photo used with permission)





Alp Cen B is an orange-red dwarf star,
like Epsilon Eridani at left center of
meteor. (See a Sloan Digital Sky Survey
field images of Alpha Centauri A and B
from WikiSky.org, and at APOD.)

This much dimmer companion star is a main sequence, orange-red dwarf (K0-1 V). It appears to have only 93.4 ± 0.7 percent of Sol's mass (Guedes et al, 2008; and Thévenin et al, 2002), about 86.5 percent of its diameter, and 45 to 52 percent of its luminosity (ESO; and Johnson and Wright, 1983, page 681). Useful catalogue numbers and designations for Alpha Centauri B include: Alp or Alf Cen B, HR 5460, Gl 559 B, Hip 71681, HD 128621, and LHS 51.

Habitable Zone around Star B

Calculations by to Weigert and Holman (1997) indicated that the distance from the star where an Earth-type planet would be "comfortable" with liquid water is centered around 0.73 to 0.74 AU -- somewhat beyond the orbital distance of Venus in the Solar System -- with an orbital period under an Earth year using calculations based on Hart (1979). More recent calculations based on Kasting et al (1993), however, allow for a wider "habitable zone." Estimates provided by the NASA Star and Exoplanet Database, however, appear to be incorrect for this spectral class K star -- where the inner edge of Star B's habitable zone should be located around 1.20 AU from the star, while the outer edge edge lies around 2.38 AUs, and so estimates from 40 Omicron Eridani A (another K0-1 star) were applied as a rough proxy, which indicated that the inner edge of Star B's habitable zone could be located around 0.56 AU from the star, while the outer edge edge lies around 1.10 AUs.

Arnold O. Benz, Institute of Astronomy, ETH Zurich

High resolution and jumbo images (Benz et al, 1998).

Proxima is a flare star, like UV Ceti (Luyten 726-8 B)
shown flaring at left. UV Ceti is an extreme example
of a flare star that can boost its brightness by five times
in less than a minute, then fall somewhat slower back
down to normal luminosity within two or three minutes
before flaring suddenly again after several hours.

Proxima Centauri b?

Using data collected up to early 1994, astronomers using the Hubble Space Telescope discerned a 77-day variation in the proper motion of Proxima (Benedict et al, 1994). The astrometric perturbations found could be due to the gravitational pull of a large planet with about 80 percent of Jupiter's mass at a 1994 separation from Proxima of about 0.17 AUs -- 17 percent of Earth's orbital distance in the Solar System from the distance, or less than half Mercury's orbital distance. The Hubble astrometry team calculated that the chance of a false positive reading from their data -- same perturbations without a planet -- to be around 25 percent.

© Estate of John Whatmough -- larger image
(Artwork from Extrasolar Visions, used with permission from Whatmough)
Glowing red through gravitational contraction, the candidate brown dwarf companion
to Proxima Centauri is depicted with two moons (one eclipsing the flare star) with
distant Alpha Centauri A and B at upper right, as imagined by Whatmough.

I

STRING THEORY FOR THE SUN !!!

A schematic diagram of the Sun-Earth magnetospheric connection. Credit: NASA/JPL/Caltech

Feb 15, 2008
A String Theory for the Sun

Filamentary Birkeland currents transport electrical energy from the Sun to Earth and the rest of the Solar System. Could ancient human beings have seen this phenomenon visible in their skies?

The auroras are caused by an intermittent bombardment of charged particles, which travel from the sun to the earth’s ionosphere in a stream called the solar wind. This was first proposed in the early 20th century by the Norwegian plasma physicist, Kristian Birkeland, and is now universally accepted. In honour of this pioneer, the exact conduits through which ions reach the earth are called Birkeland currents.

The existence of these twisted filamentary bundles of magnetic fields that transport ions through space along their length was only empirically confirmed in 2007, when NASA’s fleet of THEMIS spacecraft announced to have detected “giant magnetic ropes that connect Earth’s upper atmosphere to the Sun” in the earth’s magnetopause. Solar wind particles are believed to flow in along these ropes, “providing energy for geomagnetic storms and auroras.”

To put it bluntly, modern scientists have found that the sun has an electrical plasma connection that tapers towards the earth's magnetic poles and causes electromagnetic storms.

Curiously, ancient mythical and cosmological traditions have long anticipated the discovery of the solar wind and its Birkeland currents when they spoke about “ropes” and “strings” tying the earth to the sun. In the mystical tradition of India, the three worlds – earth, air, and sky – are attached to the sun by means of a string “by which the Devas first strode up and down these worlds, using the ‘Universal Lights’ as their stepping stones”.

In a remarkable analogy to the modern comparison of this stream to a “wind”, Hindū sages affirmed: “By the Gale, indeed, O Gautama, as by a thread, are this and yonder world and all beings strung together. Even as the thread of a gem might be threaded through a gem, even so is all this strung thereupon… to wit, Gandharvas, Apsarases, beasts, and men”, causing Deity itself to declare: “All this is strung on Me, like rows of gems upon a thread”.

The sun does “string these worlds to Himself by the thread of the Gale of the Spirit”. The identification of this “sun pillar” running through the three worlds with the polar axis of the universe makes good sense considering that the sun’s charged particles stream into the earth’s ionosphere at the auroral ovals around the poles.

If it may be granted that the Indian concept of this sun rope rooted in knowledge of the solar wind, the latter must at some point have revealed itself in an unmistakable, visible form. Is it conceivable that – at some time during the early Holocene – extreme solar weather produced such excitation that the plasma in the solar wind entered a visible glow mode, if not arc mode? If so, a substantial segment of ancient sky lore that was hitherto obscure receives some much-needed illumination.

Many corners of the world bear witness to the theme of a hero’s “noosing” of the sun. “When the sun had formed in the sky”, say the Bella Coola people of British Columbia, Canada, the creator “connected it with the earth by means of a long rope, which kept the two at a measured distance from each other and prevented that the earth would sink into the ocean”.

While an early commentator, Richard Andrée, deemed this notion "Bemerkenswert" ["remarkable"], he would never have imagined that such age-old folklore motifs could conceal some ephemeral observations of space that scientists are only now beginning to rediscover.

Contributed by Rens Van der Sluijs

www.mythopedia.info

Further reading:

The Mythology of the World Axis; Exploring the Role of Plasma in World Mythology

www.lulu.com/content/1085275

The World Axis as an Atmospheric Phenomenon

www.lulu.com/content/1305081