The horizontal axis of the H-R diagram represents which property?

The horizontal axis of the H-R diagram represents which property?

• A. Temperature
• B. Luminosity
• C. Mass
• D. Distance

Answer: (A)

Temperature is plotted on the horizontal axis of the H-R diagram, usually shown as surface temperature (often labeled by spectral type). Hotter stars sit on the left, appearing blue, while cooler stars are on the right and appear red. This arrangement contrasts with luminosity, which is on the vertical axis, reflecting how bright a star is from Earth or intrinsically. Understanding that the horizontal axis measures temperature helps explain why stars line up into patterns like the main sequence, giants, and white dwarfs, based on how hot they are relative to how bright they are. Distance isn’t a plotted axis, and mass isn’t directly shown on the diagram, though it influences a star’s temperature and luminosity.

Temperature is plotted on the horizontal axis of the H-R diagram, usually shown as surface temperature (often labeled by spectral type). Hotter stars sit on the left, appearing blue, while cooler stars are on the right and appear red. This arrangement contrasts with luminosity, which is on the vertical axis, reflecting how bright a star is from Earth or intrinsically. Understanding that the horizontal axis measures temperature helps explain why stars line up into patterns like the main sequence, giants, and white dwarfs, based on how hot they are relative to how bright they are. Distance isn’t a plotted axis, and mass isn’t directly shown on the diagram, though it influences a star’s temperature and luminosity.