Rho Ophiuchi Nebula (IC 4604)
Object Description
The reflection nebula IC 4604 (LBN 1111) belongs together with IC 4603, IC 4605, the Antares nebula vdB 107, Sharpless 2-9 and many dark clouds to a large area of nebula, the Ophiuchus Molecular Cloud. Its centre is about one degree south of the star ρ Ophiuchi, is surrounded by dense dust and is only visible in infrared images. The IC numbers were discovered in 1882 by the American astronomer Edward Barnard, who also recorded the dark clouds B 42, B 44 and B 45. [196, 239, 270, 277]
The Ophiuchus Molecular Cloud, also called Rho Ophiuchus Cloud, is an area with active star formation, which is one of the closest to us at a distance of only about 407 light years. X-ray and infrared observations revealed more than 300 young stars within the large cloud in the centre. The age of these stars is estimated to be only 300,000 years - very young compared to the oldest stars in the universe, which are more than twelve billion years old. [460]
| Designation | IC 4604 |
| Type | RN+* |
| Right Ascension (J2000.0) | 16h 25m 33.0s |
| Declination (J2000.0) | -23° 26' 36" |
| Diameter | 60 × 50 arcmin |
| Metric Distance | 0.120 kpc |
| Dreyer Description | ρ Ophiuchi in eL neb |
| Identification, Remarks | LBN 1112; ESO 517-*N3; CED 131B; Rho Oph nebula |
Finder Chart
The nebula IC 4604 is located in the constellation Ophiuchus (Serpent Bearer) and as the name «Rho Ophiuchi nebula» suggests at the 5 mag star ρ Ophiuchi, around three degrees north of the bright star Antares (α Scorpii) in the constellation Scorpius (Scorpio). The best observation time is January to September.
