An Etymological Dictionary of Astronomy and Astrophysics
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The point on the → Hertzsprung-Russell diagram of a star cluster at which stars begin to leave the → main sequence and move toward the → red giant branch. The main-sequence turnoff is a measure of age. In general, the older a star cluster, the fainter the main-sequence turnoff. Same as → turnoff point.

→ main sequence; → turnoff.

1) A small road that branches off from a larger one, or a place where one diverges from a former course.
2) An act of turning off.

→ turn; → off.

Rahgašt, from rah, variant râh "path, way," → Milky Way, + gašt, → turn.

Same as → main-sequence turnoff.

→ turnoff; → point.

A star that has ended → hydrogen burning in its core but is still burning hydrogen in a shell that surrounds the core, just before evolving into a → red giant.

→ turnoff; → star.