stellarevolution

stellarevolution - Life of the Sun (1 solar mass star) 1....

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Unformatted text preview: Life of the Sun (1 solar mass star) 1. Protostar 2. Main sequence star A region of ISM collapses due to gravity and forms a Due to extreme conditions in the core of the forming sun protostaI. Due to the collapse, the gas heats. Heated gas (15 million K core temp) H fiises to He. The star exerts a slight outward pressure. becomes a stable main sequence star when the force from fusion’s energy pushing outwards from the core equals the force of gravity inwards. 4””! \ / 2’5; * 2 1” E w 3. End of main sequence lifetime 4. Red Giant Production of He due to H fusion slows as H runs out in The increase in internal temperature allows a H-burning the core. Thus, less energy is produced so there is less shell to form around the old He core. The energy outward force to support the star against the force of produced in the shell exerts a greater force outwards than gravity inwards. This causes the sun to contract and the the force of gravity inwards. Thus the sun expands internal temperature to increase. significantly until the forces are equal again. \I 7 Life of the Sun (1 solar mass star) 5. Death — Planetary nebula 6. Death — White dwarf Over time, the core temp can reach greater than 100 Meanwhile, gravity forces the inner regions of the sun million K, which allows He to fuse to C in the core as to collapse. The collapsed core no longer has fusion well as a shell later on, This He-burning shell exerts occurring within Instead, the tightly-packed atoms such a great outward force that the outer layers of the exert a force due to the repulsion of their elections. This sun are pushed away. The ejected material is called a outward pressure, called “electron pressure”, supports “planetary nebula”. the white dwarf against the internal force of gravity. The stable white dwarf gradually cools. Stellar Evolution Lightweight stars Nebula to _) main sequence _.) red giant ._.> planetary __) white dwarf protostar (10 billion yrs for nebula 1 solar mass star) Heavyweight stars Nebula to _) main sequence _) supergiant —) type II —) Neutron star protostar (10 million yrs supernova (>3 solar masses) for l5 solar mass star) __> Black hole (>3 solar masses) ...
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This note was uploaded on 05/18/2008 for the course ASTR 101 taught by Professor Deming during the Spring '07 term at Maryland.

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stellarevolution - Life of the Sun (1 solar mass star) 1....

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