Dark Nebulae: Rho Ophiuchi Cloud Complex, Bok Globule, Barnard 68, List of Dark Nebulae, Coalsack Nebula, Horsehead Nebula, Cone Nebula

Chapters: Rho Ophiuchi Cloud Complex, Bok Globule, Barnard 68, List of Dark Nebulae, Coalsack Nebula, Horsehead Nebula, Cone Nebula, Thackeray's Globules, Dark Horse, Pipe Nebula, Snake Nebula, Dark Doodad Nebula, Barnard 147, Lynds 1616. Source: Wikipedia. Pages: 47. Not illustrated. Free updates online. Purchase includes a free trial membership in the publisher's book club where you can select from more than a million books without charge. Excerpt: The Rho Ophiuchi cloud complex is a dark nebula of gas and dust that is located 1° south of the star Ophiuchi of the constellation Ophiuchus. At an estimated distance of , this cloud is one of the closest star-forming regions to the Solar System. This cloud covers an angular area of on the celestial sphere. It consists of two major regions of dense gas and dust. The first contains a star-forming cloud (L1688) and two filaments (L1709 and L1755), while the second has a star-forming region (L1689) and a filament (L1712L1729). These filaments extend up to 1017.5 parsecs in length and can be as narrow as 0.24 parsecs in width. Some of the structures within the complex appear to be the result of a shock front passing through the clouds from the direction of the neighboring Sco OB2 association. Temperatures of the clouds range from 1322 K, and there is a total of about 3,000 times the mass of the Sun in material. Over half of the mass of the complex is concentrated around the L1688 cloud, and this is the most active star-forming region. There are embedded infrared sources within the complex. A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to be young stellar objects, including 16 classified as protostars, 123 T Tauri stars with dense circumstellar disks, and 77 weaker T Tauri stars with thinner disks. The last two categories of stars have estimated ages ranging from 100,000 to a million years. The first brown dwarf to be identified in a st...More: http://booksllc.net/?id=24813575