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What are the cold dense globules found within some H II regions?

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H II region Centre of the Orion Nebula (M42). Astronomers have identified some 700 young stars in this 2.5-light-year-wide area. They have also detected over 150 protoplanetary disks, or proplyds, which are believed to be embryonic solar systems that will eventually form planets. These stars and proplyds generate most of the nebula's light. This picture is a mosaic combining 45 images taken by the Hubble Space Telescope.

Within some H II regions, astronomers observe small, cold, and dense neutral globules embedded inside the visible plasma. These globules have a temperature of approximately 100 K and a density of about 10,000 atoms per cubic centimeter, which allows them to maintain a pressure comparable to the surrounding warm and hot materials within the nebula.1

These structures are often identified as Bok globules, which are small, dark clouds of interstellar gas and dust. Astronomers, including Bart J. Bok, have suggested that these globules represent condensed clouds of material that are in the process of contracting to form new stars.2