Rho Ophiuchi cloud complex

The Rho Ophiuchi cloud complex is a nearby grouping of molecular clouds in Ophiuchus where dense gas and dust form stars. Its dark nebulae, embedded protostars, and young stellar objects make it a well-studied early stage of star formation.

Molecular cloud: A cold, dense interstellar cloud composed mainly of molecular hydrogen, where stars can form. The complex is a nearby example of this broader kind of star-forming structure.
Lynds 1688: A dense molecular cloud in the Rho Ophiuchi complex containing active star formation. It is the complex's best-known core and a rich site of embedded young stars.
Interstellar medium: The gas, dust, and energetic particles occupying the space between stars in a galaxy. The complex is a dense, structured part of this material between stars.
Star formation: The process by which dense regions of interstellar gas and dust collapse to produce stars. The complex offers a nearby setting for studying this process across multiple stages.
Ophiuchus (constellation): A constellation on the celestial equator, located between Scorpius and Serpens. The complex lies in this constellation's direction on the sky.
Jeans instability: The gravitational instability by which a gas cloud collapses when its mass exceeds a threshold set by pressure and gravity. It describes how dense regions within the complex can begin gravitational collapse.
Lynds 1689: A molecular cloud in the Rho Ophiuchi region with dense gas and star-forming activity. It provides a neighboring cloud environment within the same complex.
Molecular hydrogen: The diatomic molecule H₂, the most abundant molecule in cold interstellar clouds. It dominates the cloud mass, although it is difficult to observe directly.
Initial mass function: The distribution of stellar masses at birth in a population of newly formed stars. Census of young objects in the complex can constrain the masses produced by a cloud.
Pipe Nebula: A large dark nebula in Ophiuchus formed by dense interstellar dust obscuring background stars. It is another prominent dark-cloud structure in the same broad region of the sky.

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Reflection nebulaBroader topic: Its varied regions show reflection nebulosity alongside obscuring dust.