Tuesday, 25 August 2020

Astrognome 100 Great Stars No. 11 Altair

 

Altair

Altair is the brightest star in one of the most prominent constellations, Aquila the Eagle. It is one of the few groups which may be said to give at least a vague impression of the object it is meant to represent. If you have sufficient imagination one can imagine the picture of an eagle in flight. The name Altair comes from the Arabic ‘Flying Eagle’


Mythologically it represented an eagle which was sent from Olympus to collect the shepherd boy Ganymede, who was destined to become the cup bearer of the gods in succession to Hebe who had tripped and fell during a very solemn ceremony.

Altair makes up a large triangle with the stars Vega in Lyra and Deneb in Cygnus. These three stars form what astronomers refer to as the ‘Summer Triangle’.


Altair has a magnitude of 0.7, making it the 12th brightest star in the sky, and has is a spectral type of A7 star which means that it is hotter than the Sun. Altair lies at a distance of 17 light years. It is the closest of the summer triangle stars.

Altair is interesting because it spins very quickly, at its the equator Altair is rotating with a speed of 286 km per second which is a significant way to a speed of 400 km per second which is the sped at which astronomers would expect the star to break apart. Altair spins so fast that it is not spherical in shape but flattened at the poles due to the high rotation speed.


Altair does have a companion star however there is no real connection between the two, this is an optical double not a binary system.


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