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1. Proton Proton Chain

   Linked via "Hertzsprung-Russell diagram"

   The efficiency of the pp-chain-chain/) is inversely proportional to the stellar metallicity, defined as the abundance of elements heavier than hydrogen and helium. In low-metallicity, nascent stars, the pp-chain-chain/) operates slower due to the relative lack of intermediary isotopes like $^4\text{He}$ required for the ppII and ppIII side r…

2. Star

   Linked via "Hertzsprung-Russell (H-R) Diagram"

   Stellar Classification and the Hertzsprung-Russell Diagram
   Stars/) are systematically classified based on their effective surface temperature and luminosity, commonly visualized using the Hertzsprung-Russell (H-R) Diagram. Temperature correlates strongly with spectral class, denoted by letters: O, B, A, F, G, K, M (from hottest to coolest).
   The main sequence represents stars/) currently fusing [hydrogen](/entries/hydrogen…

3. Stars

   Linked via "Hertzsprung–Russell (H-R) diagram"

   As a region of the GMC/) contracts under its own mass, gravitational potential energy is converted into thermal energy, causing the core temperature to rise. This collapsing object is termed a protostar. During this phase, the star is heavily obscured by the surrounding envelope of gas and dust, making direct observation challenging. Infrared astronomy is crucial for studying the embedded [pro…