An Etymological Dictionary of Astronomy and Astrophysics

The simplest molecule formed by the → cyano radical. The CN molecule is of considerable astrophysical importance, since many of its transition lines/bands are observed in various astronomical objects: interstellar medium, comets, various stars such as late-type F and G-dwarfs, and late-type giants. CN was the second interstellar molecule, after → CH (methylidine), to be identified; toward the bright star → Zeta Ophiuchi at ultraviolet wavelengths (A. McKellar, 1940 ASP Conf. Ser. 52, 187).
CN was also one of the earliest molecules to be detected in other galaxies (Henkel et al. 1988, A&A 201L, 23).

See also: → cyano-; → molecule.

The simplest molecule formed by the → cyano radical. The CN molecule is of considerable astrophysical importance, since many of its transition lines/bands are observed in various astronomical objects: interstellar medium, comets, various stars such as late-type F and G-dwarfs, and late-type giants. CN was the second interstellar molecule, after → CH (methylidine), to be identified; toward the bright star → Zeta Ophiuchi at ultraviolet wavelengths (A. McKellar, 1940 ASP Conf. Ser. 52, 187).
CN was also one of the earliest molecules to be detected in other galaxies (Henkel et al. 1988, A&A 201L, 23).

See also: → cyano-; → molecule.

Referring to → carbon, → nitrogen, and → oxygen, as in → CNO cycle
and → CNO star.

See also: → CNO.

Referring to → carbon, → nitrogen, and → oxygen, as in → CNO cycle
and → CNO star.

See also: → CNO.

A series of → nuclear reactions taking place in stars in which → carbon, → nitrogen, and → oxygen are used to transform → hydrogen into → helium. In → massive stars the carbon cycle is the dominant process of energy generation, whereas in → low-mass stars such as the Sun, the → proton-proton chain of reactions converts hydrogen into helium. The carbon cycle starts and ends with carbon-12, which acts as a catalyst in the sequential production of helium from hydrogen; neutrinos and gamma rays are also produced.

See also: → CNO; → cycle.

A series of → nuclear reactions taking place in stars in which → carbon, → nitrogen, and → oxygen are used to transform → hydrogen into → helium. In → massive stars the carbon cycle is the dominant process of energy generation, whereas in → low-mass stars such as the Sun, the → proton-proton chain of reactions converts hydrogen into helium. The carbon cycle starts and ends with carbon-12, which acts as a catalyst in the sequential production of helium from hydrogen; neutrinos and gamma rays are also produced.

See also: → CNO; → cycle.

A late → O-type star or an early → B-type star in whose spectrum the lines of some of the elements → carbon (C), → nitrogen (N),
and → oxygen (O) are present.

See also: → CNO; → star.

A late → O-type star or an early → B-type star in whose spectrum the lines of some of the elements → carbon (C), → nitrogen (N),
and → oxygen (O) are present.

See also: → CNO; → star.