Sky's Up July - September 2018 | Page 10

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Ophiuchus is full of stunning sights

Although it rides the celestial equator like all of the Zodiac constellations , the often-overlooked Ophiuchus is actually a member of the Hercules family of constellations . Visible from 80 ° north to 80 ° south , Ophiuchus covers a 948 square degree area filled with a plethora of stellar and deep sky offerings that make it a perfect target for a long night of stargazing . Far from the Serpent Bearer ’ s brightest , Barnard ’ s Star is one of its most well known residents . One of the fastest-moving stars in the sky , this red dwarf flare star , which has an apparent magnitude of 9.54 , is the fourth closest known individual star to our Sun . Ophiuchus ’ brightest star is Rasalhague , which has an apparent magnitude of 2.07 . This binary system consists of a white giant star and an orange main sequence dwarf . A few other options include Sabik , a challenging-to-resolve binary of two white dwarfs with an apparent magnitude of 2.43 ; Zeta Ophiuchi , a blue variable star ; Delta Ophiuchi , a red giant that forms a naked eye double with the yellow giant Epsilon Ophiuchi ; Beta Ophiuchi , an orange giant ; Theta Ophiuchi , a multi-star system with a spectroscopic binary ; and 70 Ophiuchi , a binary system with two orange dwarf stars . Although it is a star no longer , Kepler ’ s Supernova remnant is another notable inhabitant of the Ophiuchus Constellation . The supernova was originally observed in 1604 and was the brightest object in the sky besides the Moon for weeks . The constellation ’ s abundance of star offerings can easily fill a night of observing , but Ophiuchus also has a bounty of deep sky beauties that demand their chance in the eyepiece .
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COURTESY OF NASA , JPL-Caltech , WISE Team
Dust clouds and embedded newborn stars glow at infrared wavelengths in this tantalizing falsecolor composition from WISE ( Wide-field Infrared Survey Explorer ) of the Rho Ophiuchi Cloud Complex . This view from WISE spans almost 2 degrees and covers about 14 light-years at the estimated distance of the Rho Ophiuchi cloud .
One of the most striking might be the Dark Horse Nebula , a dark nebula that obscures part of the Milky Way ’ s upper central bulge . Appearing as a silhouette of a horse , this large dark nebula is actually a combination of smaller dark nebulae , including the Pipe Nebula and the Snake Nebula , which has a distinct S-shape . In terms of clusters , some of the standouts are Messier 10 and the less-concentrated Messier 12 , a pair of brilliant globular clusters that lie close to each other and are similarly sized ; Messier 19 , a very dense oblate globular cluster ; IC 4665 , a scattered open cluster with about 30 stars that might be visible to the naked eye under a very dark sky ; and NGC 6633 , an open cluster that is nearly as large as the full Moon and has an apparent magnitude of 4.6 . Other deep sky treasures include NGC 6572 , a planetary nebula that looks like a colored star at low magnification and can appear blue to some and green to others ; the Little Ghost Nebula , a planetary nebula with an apparent magnitude of 12.9 and a distinct ring around the white dwarf at its center ; NGC 6240 , a faint ultraluminous infrared galaxy with two distinct nuclei and an irregular structure ; and the Rho Ophiuchi Cloud Complex , a close star-forming region that is riddled with very young stars .
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