| Dark nebula | |
|---|---|
.jpg) | |
| Observation data: J2000.0epoch | |
| Right ascension | 16h 28m 06s[3] |
| Declination | –24° 32.5′[3] |
| Distance | 460ly (140pc)[4] ly |
| Apparent dimensions (V) | 4.5° × 6.5°[5] |
| Constellation | Ophiuchus |
| Designations | Ophiuchus molecular cloud, Integral 691, XSS J16271-2423 |
| See also:Lists of nebulae | |
TheRho Ophiuchi cloud complex is a complex ofinterstellar clouds with differentnebulae, particularly adark nebula which is centered 1° south of thestarρ Ophiuchi, which it among others extends to, of the constellationOphiuchus. At an estimated distance of about140 parsecs, or 460light years, it is one of the closeststar-forming regions to theSolar System.[1][6][7]
This cloud covers an angular area of4.5° × 6.5° on thecelestial 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 (L1712–L1729). These filaments extend up to 10–17.5 parsecs in length and can be as narrow as 0.24 parsecs in width. The large extensions of the complex are also calledDark River clouds[8] (orRho Ophiuchi Streamers) and are identified asBarnard 44 and 45. 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 neighboringSco OB2 association.[5]
Temperatures of the clouds range from 13–22 K, and there is a total of about 3,000 times themass of the Sun in the material. Over half of the mass of the complex is concentrated around the L1688 cloud, and this is the most active star-forming region.[5] There are embeddedinfrared sources within the complex.[9] A total of 425 infrared sources have been detected near the L1688 cloud. These are presumed to beyoung stellar objects, including 16 classified asprotostars, 123T Tauri stars with densecircumstellar disks, and 77 weaker T Tauri stars with thinner disks.[4] The last 2 categories of stars have estimated ages ranging from 100,000 to a million years.[10]
The firstbrown dwarf to be identified in a star-forming region was Rho Oph J162349.8-242601, located in the Rho Ophiuchi cloud.[better source needed][11] One of the older objects at the edge of the primary star-forming region was found to be a circumstellar disk seen nearly edge-on. It spans a diameter of 300AU and contains at least twice themass of Jupiter. The million-year-old star at the center of the disk has a temperature of 3,000 K and is emitting 0.4 times theluminosity of the Sun.[12]
The 2023NASA/ESA/CSAJames Webb Space Telescope image—released on the telescope's first anniversary—shows young stars, roughly the size of the Sun, at the center of circumstellar discs. These represent planetary systems of the future being formed in a "stellar nursery".[1][7] Since the field of view of the photo is very small, at 6.4 arc-minutes, it displays just a tiny region of what appears in most other photographs of the Rho Ophiuchi cloud complex.[13]
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