Bok globule

A Bok globule is a small, dense cloud of cold gas and dust seen as a dark silhouette against a brighter background. Some collapse under gravity to form stars.

Gravitational collapse: The inward contraction of matter under its own gravity when opposing forces cannot maintain equilibrium. A globule can contract when gravity overcomes pressure and other forms of support.
Bart Bok: A Dutch-American astronomer known for research on the Milky Way and small dark nebulae. Bok drew attention to these compact dark clouds and their possible role in star formation.
Star formation: The process by which dense regions of interstellar gas and dust collapse to form stars. Globules offer relatively compact sites for studying this process.
Bok globule CB 17: A dark globule in the constellation Cassiopeia that contains evidence of low-mass star formation. CB 17 provides a named case for comparing globule structure and embedded activity.
Magnetic support: The resistance to gravitational collapse provided by magnetic fields in a cloud. Magnetic fields may delay or redirect collapse inside a dense globule.
Jeans instability: The condition in which a gas cloud becomes gravitationally unstable below a critical temperature or above a critical mass or density. It describes when a cold, dense globule can fragment or begin collapsing.
Globule: A small, rounded concentration of material distinct from its surroundings. The astronomical name describes the object's compact, rounded appearance.
Infrared astronomy: The study of astronomical objects using infrared radiation. Infrared observations can reveal warm embedded sources hidden by a globule's dust.
Lynds Dark Nebula 183: A large, cold, starless dark cloud in the constellation Serpens. L183 is more extended than a typical Bok globule and illustrates a different scale of dark cloud.
Turbulence: Irregular, chaotic motion in a fluid across a range of spatial scales. Internal turbulent motions can support a globule or promote dense substructure.

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