globule

n.
A small spherical mass, especially a small drop of liquid.

[French, from Latin globulus, diminutive of globus, sphere.]

A small, opaque nebula seen in silhouette against a rich star field or a bright nebula. Globules were first cataloged in the 1920s. In 1947, B. J. Bok called attention to their potential significance for star formation, and since then they have been commonly known as Bok globules. A globule is a region of the interstellar medium containing a high density of interstellar grains that obscure the more distant background stars and cause the region to appear as a dark nebula in optical photographs. Only relatively nearby globules can be identified, because if there are many stars in front of the nebula the contrast with the background is too weak. See also Nebula.

The material contained in interstellar grains represents only a small fraction (about 1%) of the total mass of a globule; most of its mass is in gaseous form. The grains play a key role in shielding the nebular gas from the surrounding starlight, thus creating an environment in which molecules can survive and interact. Radio astronomers have been able to detect carbon monoxide (CO) emission lines in dark nebulae, and in the densest cores of nebulae heavier molecules have been identified. Dark nebulae are now commonly called molecular clouds; the most abundant molecule is molecular hydrogen, but it is difficult to detect directly. See also Interstellar matter; Molecular cloud; Radio astronomy.

A typical (molecular core) globule has a diameter of 0.1 parsec (1 parsec = 1.9 × 10¹³ mi or 3.1 × 10¹³ km) and mass four times that of the Sun; larger, more massive globules are also known. The kinetic temperature in a globule is low; it is estimated to be about 10 K (−442°F).

Calculations predict that in the absence of internal support a typical globule undergoes gravitational collapse in less than a million years to produce one or more protostars. Some but not all globules have given birth to protostars, and these probably represent the youngest stars of the Milky Way. See also Protostar; Stellar evolution.

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noun

A quantity of liquid falling or resting in a spherical mass: driblet, drop, droplet. See dry/wet.

A small spherical mass; a little globe or pellet, as of medicine. See also morgagnian globule.

• g. leukocyte — mononuclear cell with large eosinophilic cytoplasmic granules found in the intestinal epithelium.

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Dansk (Danish)
n. - dråbe, perle, lille kugle

Nederlands (Dutch)
druppel, pil

Français (French)
n. - gouttelette (de)

Deutsch (German)
n. - Tröpfchen, Kügelchen

Ελληνική (Greek)
n. - σταγονίδιο, σφαιρίδιο, (βιολ.) αιμοσφαίριο

Italiano (Italian)
globulo

Português (Portuguese)
n. - glóbulo (m)

Русский (Russian)
шаровидная частица, красный кровяной шарик, пилюля

Español (Spanish)
n. - glóbulo, gota

Svenska (Swedish)
n. - klot, droppe, pärla

中文（简体）(Chinese (Simplified))
小球, 小滴, 水珠, 药丸

中文（繁體）(Chinese (Traditional))
n. - 小球, 小滴, 水珠, 藥丸

한국어 (Korean)
n. - 작은 구 모양

日本語 (Japanese)
n. - 小球体, 小滴, 溶滴, 粒

العربيه (Arabic)
‏(الاسم) كريه : كرة صغيرة‏

עברית (Hebrew)
n. - ‮כדורית, נטף, טיפה, גלולה‬

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