Post by glactus on Feb 17, 2008 7:03:46 GMT
Ophiuchus, the snake charmer, is the thirteenth of the twelve constellations of the Zodiac. It is the forgotten constellation, perhaps, for the Sun actually spends more time before the stars of Ophiuchus (19 days) than it does in neighboring Scorpius (6 days). It has eight Messier objects, mostly globular clusters. But Ophiuchus, not so well known as neighboring Scorpius or Sagittarius of the Zodiac constellations, has much to draw your attention during summer evenings.
Notable stars:
Barnard's star
More famous than any of these is Barnard's Star, which lies just under six light years from Earth, and is one of the Sun's closest neighbours. It is a very small and faint red star of the type known as subdwarfs, so that despite being so nearby, it is invisible to the naked eye. Magnitude is 9.55 and distance from earth is 5.99 light years
Alpha Ophiuchi
The brightest star, alpha Ophiuchi, is better known as Rasalhague, meaning "Head of the Snake Charmer". This is a rather close star, at 54 light years away, and a celestial neighbour of Ras Algethi (alpha Herculis), which lies to the WNW five degrees. Magnitude of alpha Ophiuchi is 2.08
Rio Ophiuchi a and Rio Ophiuchi b
Rho Ophiuchi. A pair of two very blue stars. Both are at the end of their main sequence phase and will soon start to expand to red giants. a's magnitude is 5.0 and b's in 5.9. Distance from earth is 395 light years.
70 Ophiuchi a and 70 Ophiuchi b
This pair are located about 16.6 light-years away in the north - eastern part of the constellation. Both are main sequence orange red dwarfs. a with a magnitude of 4.22, and b with a magnitude of 5.9
Notable objects:
Kepler's remnant
The explosion of the star that created the Kepler remnant blasted the stellar remains into space, heating the gases to millions of degrees and generating highly energized particles. Copious X-ray light, like that shining from many supernova remnants, was produced. The presence of large amounts of iron and the absence of a detectable neutron star points toward a so-called Type Ia supernova thermonuclear explosion. Magnitude is - 2.5 and distance from Earth is 13,000 light years.
NGC 6240
The extraordinarily bright galaxy NGC 6240 is roughly 400 million light years away from earth and is a prime example of the collision and subsequent merging of two galaxies causing "fireworks" as new stars are created. Over the next few hundred million years, the two black holes in NGC 6240, which are roughly 3000 light years apart, will drift toward each other and eventually merge to form an even larger, supermassive black hole. Magnitude is 12.8.
NGC 6369
This pretty planetary nebula, cataloged as NGC 6369, was discovered by 18th century astronomer William Herschel as he used a telescope to explore the constellation Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the popular moniker of Little Ghost Nebula. The nebula's main ring structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. Magnitude is 12.9 and distance from earth is 2,000 light years.
Messier M 10
M10 was discovered by Charles Messier and added to his catalogue in 1764, describing it as a nebula without stars in the belt of Ophiuchus. This nebula is beautiful and round;and is easily visible in binoculars or small telescopes, but to resolve individual stars needs a telescope of at least 100mm or 4- inch aperture. Magnitudeis 6.6 and distance from Earth is 14,300 light years.
Kepler's remnant
credits:
Ophiuchus map: Wikipedia
en.wikipedia.org/wiki/Ophiuchus
Sun map: wingmakers
home.xtra.co.nz/hosts/Wingmakers/Ophiuchus.html
image: Kepler's remnant: NASA/CXC/NCSU/S.Reynolds et al. www.eastbayastro.org/articles/lore/ophiuchus.htm
image: NGC 6240: Chandra
chandra.harvard.edu/photo/2007/kepler/index.html
image: NGC 6369:
antwrp.gsfc.nasa.gov/apod/ap021108.html
image: Messier M 10:
www.aldebaran.cz/astrofyzika/orientace/constellations/Oph.html