noun
Hertzsprung-Russell diagram; HR diagram
Rare, technical term in astronomy. The abbreviation HR図 (HRず) is more common.
See also: ＨＲ図
天文学の教科書でヘルツシュプルングラッセル図を見たことがありますか。
Have you ever seen a Hertzsprung-Russell diagram in an astronomy textbook?
Common abbreviation for the same diagram; much more frequently used than the full term.
From the names of astronomers Ejnar Hertzsprung and Henry Norris Russell, plus 図 (diagram).