If you didn’t get a chance to watch the IYA telescope “live” on Galactic TV today, don’t worry. We took a video capture for you. Step inside to enjoy today’s view of Alpha Centauri…
Alpha Centauri (alpha Centauri / alpha Cen); (also known as Rigil Kentaurus, Rigil Kent, or Toliman) is the brightest star in the southern constellation of Centaurus and an established binary star system, Alpha Centauri AB (alpha Cen AB). To the unaided eye it appears as a single star, whose total visual magnitude identifies it as the third brightest star in the night sky. Alpha Centauri is the closest star system to the Solar System, being only 1.34 parsecs, or 4.37 light years away from our Sun.
Popularly known, Alpha Centauri is the closest star system to our Solar System. It lies about 4.37 light-years in distance, or about 41.5 trillion kilometres, 25.8 trillion miles or 277,600 AU. Astronomer Thomas James Henderson made the original discovery from many exacting observations of the trigonometric parallaxes of the AB system between April 1832 and May 1833. He withheld the results because he suspected they were too large to be true, but eventually published in 1839 after Friedrich Wilhelm Bessel released his own accurately determined parallax for 61 Cygni in 1838. For this reason, we consider Alpha Centauri as the second star to have its distance measured.
Alpha Centauri A is the principal member or primary of the binary system, being slightly larger and more luminous than our Sun. It is a solar-like main sequence star with a similar yellowish-white colour, whose stellar classification is spectral type G2 V. From the determined mutual orbital parameters, Alpha Cen A is about 10% more massive than our Sun, with a radius about 23% larger.
Alpha Centauri B is the companion star or secondary, slightly smaller and less luminous than our Sun. This main sequence star is of spectral type of K1 V, making it more an orangish-yellow color than the whiter primary star. Alpha Cen B is about 90% the mass of the Sun and 14% smaller in radius. Although it has a lower luminosity than component A, star B’s spectrum emits higher energies in X-rays. The light curve of B varies on a short time scale and there has been at least one observed flare.
Together, the bright visible components of the binary star system are called Alpha Centauri AB (Alpha Cen AB). This “AB” designation denotes the apparent gravitational centre of the main binary system relative to other companion star(s) in any multiple star system. “AB-C” refers to the orbit of Proxima around the central binary, being the distance between the centre of gravity and the outlying companion. Some older references use the confusing and now discontinued designation of A×B. Since the distance between the Sun and ? Cen AB does not differ significantly from either star, gravitationally this binary system is considered as if it were one object.
Alpha Centauri C, also known as Proxima Centauri, is of spectral class M5Ve or M5VIe, suggesting this is either a small main sequence star (Type V) or sub-dwarf (VI) with emission lines, whose B-V colour index is +1.81. Its mass is about 0.12 M. R.T.A. Innes from South Africa in 1915 discovered Proxima Centauri by blinking photographic plates taken at different times during a dedicated proper motion survey. This showed the large proper motion and parallax of the star was similar in both size and direction to those of ? Centauri AB, suggesting immediately it was part of the system and slightly closer to us than ? Centauri AB. Lying 4.22 light-years away, Proxima Centauri is the nearest star to the Sun. All current derived distances for the three stars are presently from the parallaxes obtained from the Hipparcos star catalog (HIP).
As always, you can visit the remote telescope by clicking on the IYA “LIVE Remote Cam” Logo to your right. We’ll be broadcasting whenever skies are clear and dark in Central Victoria! Enjoy….
Information Courtesy of Wikipedia