Capella

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Capella is the brightest star in the constellation Auriga, the sixth brightest in the night sky and the third brightest in the northern celestial hemisphere, after Arcturus and Vega. Its name is derived from the diminutive of the Latin capra “goat”, hence “little goat”. Capella also bears the Bayer designation Alpha Aurigae (often abbreviated to α Aurigae, α Aur or Alpha Aur). Although it appears to be a single star to the naked eye, it is actually a star system of four stars in two binary pairs. The first pair consists of two bright, large type-G giant stars, both with a radius around 10 times that of the Sun and two and a half times its mass, in close orbit around each other. Designated Capella Aa and Capella Ab, these two stars are thought to be cooling and expanding on their way to becoming red giants. The second pair, around 10,000 astronomical units from the first, consists of two faint, small and relatively cool red dwarfs. They are designated Capella H and Capella L. The stars labelled Capella C through to G and I through to K are actually unrelated stars in the same visual field. The Capella system is relatively close, at only 42.2 light-years (12.9 pc) from Earth.

Imaging cameras: Canon EOS 6D (unmodified)
Mounts: Benro B4 ballhead, Benro C2580T
Guiding telescopes or lenses: Sigma 105mm f/2.8 EX DG OS HSM macro
Software: Adobe Lightroom 5, Adobe Photoshop CS2, Hugin Team Hugin 2013
Accessories: AstroTrac TT 320
Resolution: 2000×854
Dates: Oct. 16, 2014
Frames: 20×120″
Integration: 0.7 hours
Avg. Moon age: 22.32 days
Avg. Moon phase: 48.17%
RA center: 80.029 degrees
DEC center: 47.317 degrees
Pixel scale: 20.666 arcsec/pixel
Orientation: -46.603 degrees
Field radius: 6.243 degrees

Аuthor: Ville Miettinen, 25.10.2014

Astrophotography of the day of SPONLI