Die ARA CONSTELLATION - Mythen, Fakten und Standort

The 9th luminous, binary star system in all the heavens. Achernar is a well-known sight to observers in the Southern Hemisphere. It shines as brightly as the brightest stars with a magnitude of 0.45.

The two stars, Achernar A (seven times the mass of the sun) and Achernar B (the smaller one), rotate about 6.7 the earth-sun’s distances. Achernar is sometimes not sighted by Northern Hemisphere observers, despite its position in the top 10 stars in the sky, perhaps because it is invisible above 32 degrees north latitude.

Geschichte und Mythologie von Achernar

The name Achernar is derived from an Arabic phrase meaning ‘the end of the river’, however the star’s official name is Alpha Ariadne. The star we now know as Theta Eridani, or Acamar got the name Achernar in the early classical times. At that time, Acamar was the brightest star of the constellation visible from Greece.

The former Achernar became Acamar and the brightest star father became Achernar after the voyagers discovered it.

Ursprünglich wurde Achernar nicht als Teil des Sternbilds betrachtet. Seine Lage ist:

  • Rektaszension: 1 Stunde 37 Minuten 42,9 Sekunden

  • Deklination: -57 Grad 14 Minuten 12 Sekunden

Die Wissenschaft von Achernar

Much hotter and brighter than the sun, it is a B3V star, denoting that it belongs to the list of “normal” stars known as the “main sequence”. It is nearly 1100 times as bright, visually, as our neighborhood star. It produces more energy in the non-visible ultraviolet (UV) wavelengths. It pumps out some 3,000 to as much as 5,000 times the solar energy level.

It’s brighter, hotter (and bluer) than the sun. Its mass is 6-8 times and average diameter nearly 8-10 times respectively that of our sun.

Die abgeflachte Form des Achernar

While our sun spins on its axis once about every 25 days, Achernar’s rotation lasts up to two more days, or approximately 15 times quicker than our sun. This fast rotation of Achernar results in an odd, flattened shape.

Die Kraft der Drehung flacht den Stern beträchtlich ab, wobei sich sein Äquator um etwa 50 Prozent stärker ausbeult als seine Pole. Die Form wurde erstmals 2003 von der Europäischen Südsternwarte mit einem sehr großen Teleskop entdeckt. Bei näherer Betrachtung sieht Achernar eher wie ein blaues M&M aus, während unsere Sonne eher wie ein orangefarbenes aussehen würde.

The flattening actually causes the star’s poles to be hotter than the equator, making an exact surface temperature for this star hard to determine.

Wie kann man Achernar sehen?

To see Achernar well, you must be even further south – around 25 degrees N. latitude. On most nights of the year, this star cannot be seen easily anywhere near North America. But around October 20 it circumnavigates the southern horizon around midnight. Then as the month’s days pass, Achernar can be seen around in November at 10 p.m., 8 p.m. in December and just after the sunset in January.

But with a dark sky and far enough to South, you can see Achernar easily. After all, this star is very bright!