1. Stellar Stages

3. can be seen from Doppler shift as it contracts

4. cloud can break up and continue contraction takes about 1 mil years

5. stars rarely occur in isolation as they increase in size, the radiation can not easily escape and they heat up internally pressure also increases as a result

7. Stage: 2 and 3 contracting fragments temp is only slightly lower than that of the parent cloud. Due to energy still constantly being radiated by the cloud (not reabsorbed) as the cloud reaches a sphere roughly the size of the solar system, then it reaches stage 3 the inner regions become opaque to radiation so it gets absorbed. temp reaches about 10000 k. the dense opaque region is considered a protostar. mass continues to increase because the pressure from the protostar is not strong enough to equal out gravity photospheres/ surface is evident

8. Stage: 4 protostar as it evolves, its density increases as it shrinks and its temp increases about 100,000 yrs and with a center around 1000000 k needs 10^7 k to ignite proton-p[proton reaction about the size of mercury’s orbit, high luminosity not from burning, but from gravitational contraction

9. Protostar

10. Stage 5: protostar evolution still contracting, no equilibrium being reached. heat from internal pressure is high but much gets too surface and is radiated away 10x solar value. 4000 k surface, and 5milk k core all gas is ionized called t-tauri phase, its characterized by higher disturbance, bipolar flow with two large jets of matter further along in this stage, the slower evolution occurs

11. stage 6 & 7: New star 10 mil years to get there, 1 mil km across, 10 mil k core h+h-> He for stage 6, there is a dust cocoon that is eventually dispersed by stage 7. this absorbs radiation and re-emits it core contracts, heats up to 15 mil k surface 6000 k then hits main sequence.

12. New star formation