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# H-R Diagram

• Hertzspring-Russell diagram
• Plots luminosity on the $y$-axis
• Plots either temperature or spectral type on the $x$-axis
• Main sequence stars represent a relationship between temperature and luminosity that most stars follow
• A band running from upper left (hot, more luminous) to the lower right (cool, less luminous)
• Hotter stars are more luminous than cooler ones
• More massive stars are hotter than less massive ones
• More mass --> more gravity --> greater compression at their core
• Greater compression at the core leads to better energy generation and thus more luminosity and heat
• Can be used to measure the distance of stars