The Constellation Reticulum
Posted by Brian Ventrudo
Just south of the lone star Achernar, and nearly halfway between Achernar and brilliant Canopus, lies the small but distinctive southern constellation Reticulum. This star group rises over just northeast of the Large Magellanic Cloud in the mid-evening hours during southern spring, and holds a lovely double star easily observed in binoculars.
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Despite its diminutive size, the quadrilateral of Reticulum stands out quite nicely in this star-poor part of the sky, and there is a lovely field of isolated stars just east of alpha (α) Reticuli.
With binoculars, linger over the stars of this small constellation and look for the differences in colour. There are orange stars here mostly, with one or two red and blue stars. The colour of stars reveals their surface temperature. Red stars are cool, perhaps 3,500 K to 4,000 K. Orange stars a little warmer, yellow warmer still, and white and blue stars are hottest, with temperatures of 10,000 K to 20,000 K depending on their mass. It is an astonishing feat that with a keen eye and a pair of binoculars, you are able to discern the temperature of a burning ball of gas dozens or hundreds of light years away!
The constellation Reticulum between the stars Achernar and Canopus. The wide double star zeta Reticulii is marked in red. Click image to enlarge.
Reticulum has a lovely double star for binoculars. It is zeta (ζ) Reticuli, located on the western end of the constellation. The pair is not separable without optics, but binoculars show a pair of golden yellow stars about 1/10 degree apart. Astronomers have determined that each component of zeta (ζ) Reticuli is very much like our Sun. The pair lies some 40 light years from Earth.
Recticulum was created in the 1750′s by Nicolas Lacaille, who named more than a dozen new constellations in the southern skies, most of them after scientific instruments. A reticulum, or reticle, is a grid or pattern in an optical instrument used to measure size and position.
