Lesson 1.2 Understanding the Hertzsprung-Russell DiagramVersión en línea Explore the Hertzsprung-Russell Diagram and its significance in stellar classification. por Eric D Norman 1 Introduction to the Hertzsprung-Russell Diagram The Hertzsprung-Russell Diagram, often abbreviated as H-R Diagram, is a pivotal tool in astronomy used to classify stars based on their luminosity, color, and temperature. 2 Axes of the H-R Diagram The H-R Diagram features two axes:X-axis: Represents the temperature of stars, typically measured in Kelvin, decreasing from left to right.Y-axis: Represents the luminosity of stars, often expressed in terms of the Sun's luminosity. 3 Main Regions of the H-R Diagram The H-R Diagram is divided into several key regions:Main Sequence: Diagonal band where most stars, including the Sun, reside.Giants: Located above the main sequence, these stars are larger and more luminous.Supergiants: Extremely bright and massive stars found at the top of the diagram.White Dwarfs: Small, dense remnants of stars located in the lower left corner. 4 Stellar Evolution and the H-R Diagram The H-R Diagram illustrates the life cycle of stars. As stars evolve, they move across the diagram:Stars begin on the main sequence.They expand into giants or supergiants as they exhaust their nuclear fuel.Eventually, they may shed their outer layers, becoming white dwarfs. 5 Color and Temperature Correlation There is a direct correlation between a star's color and its temperature:Blue Stars: Hotter, with temperatures exceeding 30,000 K.Yellow Stars: Moderate temperatures, like our Sun, around 5,800 K.Red Stars: Cooler, with temperatures below 3,500 K. 6 Categories of Stars Main Sequence StarsNuclear Fusion OccursProduction of helium from fusion of hydrogenRed GiantsHydrogen runs out and Helium fusion beginsWhen iron is produced, it shed its core and becomes a planetary nebulaRed SupergiantsWhen hydrogen runs out and iron produced the star goes SupernovaSupernovaSupernovas are found at the top right left corner of the HR diagram (Super bright and Super hot)Supernovas lead to the production of heavy metals
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