An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) A Hydroxyl radical formed by abstraction of a hydrogen atom from water.
2) An OH group within a molecule.

From → hydro- + ox(y)- a combining form meaning "sharp, acute, pointed, acid," used in the formation of compound words, from Gk, oxys "sharp, keen, acid" + -yl a suffix used in the names of chemical radicals, from Fr. -yle, from Gk. hyle "matter, substance."

Emission or absorption lines on an electromagnetic spectrum generated by hydroxyl, → OH molecules. At present, four principal lines are known in the radio domain at frequencies of 1612, 1665, 1667, and 1720 MHz, or wavelengths of approximately 18 centimeters.

→ OH; → line.

A → maser phenomenon created by → OH molecules with characteristic → OH lines. OH masers are detected toward a variety of astronomical environments, including massive star formation regions and evolved late-type stars.

→ OH; → maser.

An astronomical source emitting microwave radiation characteristic of the hydroxyl OH molecule, especially one showing a maser effect. OH sources are found in molecular clouds in interstellar medium and in the cool envelopes of evolved stars.

OH, chemical compound hydroxyl; → source.

An evolved Mira-type star which is associated with strong OH maser and strong infrared (IR) emission from the surrounding shell of warm gas and dust.

→ OH; → infrared; → star.