Adara (Epsilon Canis Majoris) -- Double Star in Canis Major
Adara – Our Brightest Star in Tens-of-Millions of Years
Adara blazed in the night sky (magnitude -3.99) 4.7 million years ago. No other non-exploding
star has shined that bright since then, or will for at least, another 5 million years into our future.
Even today it is the brightest extreme-ultraviolet light source in the sky.
Adara (Epsilon Canis Majoris) is currently the 22nd brightest star in the night sky. It is the 2nd
brightest star in Canis Major (Sirius is the brightest); even though Adara’s Greek Letter
Designation suggests otherwise. It is a young star only 22.5 million years old and about 14
times the size of our sun. The name “Adara” is a derivative of the Arabic word for “Virgins”.
Adara is also a double star that tests one’s telescope optics. Adara's companion star is
separated by 7.0 arcseconds from Adara and thus one would think that it would be an easy split
in a telescope – which is just not the case. The problem is twofold. First, Adara shines 250x
brighter than its companion star, smothering its companion with excess light. Good, clean
optics that limit light scatter inside the telescope is a must. The second issue is that Adara,
from Central Maryland, is low in the southern sky which increases the amount of atmosphere the
star’s light must pass through and therefore, further scatters the bright light from Adara.
If everything is right with the universe, Adara can be split. On February 25th it split nicely in the
155mm refractor at 182x from my house – but the night before, on February 24th the companion
stayed hidden at the same magnification.