An Etymological Dictionary of Astronomy and Astrophysics

A feature in a stellar spectrum showing strong hydrogen and helium emission lines with absorption lines on their blueward wing. This line profile indicates a strong outflow of matter from a star. → inverse P Cygni line profile.

See also: After → P Cygni star.

A feature in a stellar spectrum showing strong hydrogen and helium emission lines with absorption lines on their blueward wing. This line profile indicates a strong outflow of matter from a star. → inverse P Cygni line profile.

See also: After → P Cygni star.

1. A variable star in the constellation → Cygnus, and one of the most luminous stars in the Milky Way Galaxy. It is a → Luminous Blue Variable (LBV)
   star of → spectral type B2 Ia located about 7000 light-years away. It was unknown until the 17th century, when it suddenly brightened to third magnitude. It briefly disappeared and returned, and today has a magnitude of about 4.8.
   

2. A member of a class of high-luminosity, early-type stars, in which spectral lines have a characteristic → P Cygni profile.

See also: P, letter of alphabet; Cygni, pertaining to → Cygnus; → star.

1. A variable star in the constellation → Cygnus, and one of the most luminous stars in the Milky Way Galaxy. It is a → Luminous Blue Variable (LBV)
   star of → spectral type B2 Ia located about 7000 light-years away. It was unknown until the 17th century, when it suddenly brightened to third magnitude. It briefly disappeared and returned, and today has a magnitude of about 4.8.
   

2. A member of a class of high-luminosity, early-type stars, in which spectral lines have a characteristic → P Cygni profile.

See also: P, letter of alphabet; Cygni, pertaining to → Cygnus; → star.

Acoustic waves trapped inside stars, which act as a resonating cavity, exhibiting millions of oscillation modes or standing waves. Same as → pressure mode. P-mode oscillations in the Sun have frequencies in the 0.2-5.5 mHz range. They are particularly intense in the 2-4 mHz range, where they are often referred to as solar “5-minute oscillations.”
See also → pulsation mode.

See also: P, referring to pressure; → mode.

Acoustic waves trapped inside stars, which act as a resonating cavity, exhibiting millions of oscillation modes or standing waves. Same as → pressure mode. P-mode oscillations in the Sun have frequencies in the 0.2-5.5 mHz range. They are particularly intense in the 2-4 mHz range, where they are often referred to as solar “5-minute oscillations.”
See also → pulsation mode.

See also: P, referring to pressure; → mode.

Same as → parity symmetry.

See also: → parity; → symmetry.

Same as → parity symmetry.

See also: → parity; → symmetry.

→ compressional wave.

See also: P, referring to → pressure; → wave.

→ compressional wave.

See also: P, referring to → pressure; → wave.