HR Diagram - EcchiRs

Japanese: HR 図 - えっちあーるず

...However, stars with low mass go through a period of giant or subgiant starhood before the main sequence, and T Tauri stars are one of these. Most stars are main sequence stars, and are so named because they are distributed in a row on the Hertzsprung-Russell diagram (HR diagram) described below. Main sequence stars, like the Sun, are stars that generate energy in their centers through thermonuclear reactions that convert hydrogen into helium. ...

From [Star Cluster]

…Because the stars in a cluster are at roughly the same distance, their absolute luminosities can be directly compared with one another with high accuracy. The Hertzsprung-Russell diagram (HR diagram) allows us to trace the evolution of the stars, determine their masses, and give us a clue to the age of the cluster. The HR diagram is a plot of the surface temperature, color, or spectral type of the stars on the horizontal axis, and the absolute luminosity of the stars on the vertical axis. …

From the Hertzsprung-Russell diagram

...A chart with the spectral type of stars on the horizontal axis and the absolute magnitude of stars on the vertical axis. It is also called the HR chart for short. E. Hertzsprung created a chart in 1911 showing the color index of stars in the Pleiades and Hyades clusters on the horizontal axis and the apparent magnitude on the vertical axis, and in 1913 HN Russell created a chart with the absolute magnitude based on the parallax of several dozen stars, which had only just been obtained at that time, on the vertical axis.

*Some of the terminology that refers to the "HR diagram" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…ただし，質量のあまり大きくない星ではこの主系列前の巨星または亜巨星の時期があり，おうし座T型星はこれに相当する。恒星の大部分は主系列星であり，後出のヘルツシュプルング=ラッセル図(HR図)上に列をなして分布するのでこの名がある。主系列星は太陽と同じく中心部で水素をヘリウムに転換する熱核反応によってエネルギーを供給している恒星である。…

【星団】より

…星団の恒星はほぼ同じ距離にあるので，恒星の絶対光度を直接相互に高い精度で比較できる。　ヘルツシュプルング=ラッセル図(HR図)は恒星の進化のようすをあとづけて個々の恒星の質量を知り，星団の年齢を知るための手がかりを与えてくれる。HR図とは，横軸に恒星の表面温度または色またはスペクトル型をとり，縦軸に恒星の絶対光度をとった図である。…