Barnard 68

Barnard 68 is a molecular cloud, dark absorption nebula or Bok globule within our own galaxy. Because of its opacity, its interior is extremely cold, its temperature being about 16 K (−257 °C). Its mass is about two astronomical masses and it measures about half a light-year across.

Characteristics

For more information about Dark Clouds, see Dark cloud.

Careful measurements of the degree of obscuration resulted in a finely sampled and accurate mapping of the dust distribution inside the cloud. If not disrupted by external forces, the stability of dust clouds is a fine balance between outward pressure caused by the heat or pressure of the cloud's contents, and inward gravitational forces generated by the same particles. This causes the cloud to wobble or oscillate in a manner not unlike that of a large soap bubble or a water-filled balloon which is jiggled. In order for the cloud to become a star, gravity must gain the upper hand long enough to cause the collapse of the cloud and reach a temperature and density where fusion can be sustained. When this happens, the much smaller size of the star's envelope signals a new balance between greatly increased gravity and radiation pressure.

Barnard 68's well-defined edges and other features show that it is on the verge of gravitational collapse within the next 100,000 years or so, and is on its way to becoming a star.