Altair


Altair. Steve Johns 2013 Cleveland, Ohio USA

Altair. Steve Johns 2013 Cleveland, Ohio USA

I always wondered why Altair looks different in my images.

It seems every time I capture an image of Altair, it shows a horizontal spike of light on each side of it. All other stars both dim and bright do not manifest this anomaly. I decided to research the issue. I found some clues at SolStation.com. I have learned that this star has a very fast rotational axis spin. “Altair has one of the fastest known rotational speeds — 210 kilometers per second (131 miles per second)– and so completes at least one rotation in about 10.4 hours. By comparison, the rotational speed of Sol is only 25.4 days at its equator. As a result of the rapid spinning, the star probably has the shape of a flattened ellipsoid, where the equatorial diameter was estimated to be 14 percent greater than the polar diameter in 2001” (Solstation, 2013).

Add to the rotation spin the gas nebulae and the dust that has been detected surrounding it, and the flattening of the sphere from rapid spinning. As Solstation explains: “…dust has been detected around this young star (Kuchner et al, 1998 — in pdf). According to Holweger et al (1999), this dust disk may have developed after most of the surrounding nebulae of gas has been absorbed or expelled as a shell of gas from the developing star before it reached the main sequence”…As a result of the rapid spinning, the star probably has the shape of a flattened ellipsoid, where the equatorial diameter was estimated to be 14 percent greater than the polar diameter in 2001“(Solstation, 2013).

– Hence the anomaly of the image.

Altair

Altair

Reference:

Solstation.com (2013). Retrieved from http://solstation.com/stars/altair.htm

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