(planets created during the disk phase remove the disk, leaving a main sequences star & planets. ). Final stage of stars life depends on mass[mass determines lum., temp, and lifespan]- Red dwarf, sun-like stars, massive stars. Fate o f Red Dwarf -H fuses to He in core, convection mixes the He throughout and converts all H to He. Fate of Sun-life star-> H in core will run out, causing fusion to stop, core heats up, gravity > pressure, fusion ignites shell around core, lum. ^, outer layers of star expand & cool, pressure > gravity, becomes red giant/white dwarf(carbon/oxygen ash). Fate of massive star -> from main seq. to red supergiant to blue supergiant (He fuses to C in core) Brown Dwarf-> failed stars, common, still have thermal energy. Main Sequence Stars-> Fused H into He in their cores, called H burning. 90% of its life in this phase, remaining in this phase as long as the H lasts. Low mass stars - lower pressure, lower temp, slower fusion, lower luminosity. High mass stars- higher pressure, higher temp, rapid fusion, higher luminosity. Scorched Earth -> sun will increase lum. By 10% over next 1-2 billion years, oceans will evaporate away, water destroyed by solar UV light, kill atmosphere, vaporize earth’s crust. Planetary Nebula-> nothing to do with planets, just looks round and looks like one, it is a UV radiation from the hot core ionizes the cast off layers. White dwarf - has high density.
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