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Models. A stellar evolutionary model is a mathematical model that can be used to compute the evolutionary phases of a star from its formation until it becomes a remnant. The mass and chemical composition of the star are used as the inputs, and the luminosity and surface temperature are the only constraints.
The collapsing clump compresses and heats up. The collapsing clump begins to rotate and flatten out into a disc. The disc continues to rotate faster, draw more gas and dust inward, and heat up. After about a million years or so, a small, hot (1500 degrees Kelvin), dense core forms in the disc's center called a protostar.
Apr 11, 2022 · The first step in the process of creating stars is the formation of dense cores within a clump of gas and dust (Figure 21.1.7 21.1. 7 (a)). It is generally thought that all the material for the star comes from the core, the larger structure surrounding the forming star.
Small, relatively cold, low-mass red dwarfs fuse hydrogen slowly and will remain on the main sequence for hundreds of billions of years or longer, whereas massive, hot supergiants will leave the main sequence after just a few million years. A mid-sized star like the Sun will remain on the main sequence for about 10 billion years.
- Clues from Our Past
- Looking to Our Future
- Building Our Knowledge of How Stars and Planets Begin
In cosmic phenomena, we see echoes of our distant past. Massive clouds of gas and dust condense into centralized protostars, that in turn emit powerful solar wind and bursts of radiation. A newborn star emerges from its molecular cloud nursery. Material left over from the star’s formation collapses into protoplanets. Each of these observations—now ...
Stars follow different paths as they age, determined by their mass, with the most massive burning their fuel exponentially faster. Smaller stars, like our Sun, live long lives. As they start to run out of hydrogen fuel in their core, they expand and turn red, becoming red giants. The byproducts of fusion collect in the core and, if the star is mass...
Our current understanding of how, when, and where stars and planets form and evolve is advanced through theory and observation. Data from current and next-generation telescopes will inform new computational models for stellar and planetary life cycles. These models are refined and may yield new theoretical discoveries which are in turn tested again...
When the star’s central temperature becomes high enough (about 12 million K) to fuse hydrogen into helium, we say that the star has reached the main sequence (a concept introduced in The Stars: A Celestial Census). It is now a full-fledged star, more or less in equilibrium, and its rate of change slows dramatically.
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Apr 11, 2022 · Eventually, as stars age, they evolve away from the main sequence to become red giants or supergiants. The core of a red giant is contracting, but the outer layers are expanding as a result of hydrogen fusion in a shell outside the core. The star gets larger, redder, and more luminous as it expands and cools.
