Star Formation

M16, Eagle Nebula Fig. 18.9

In Fig (b)

Green: HII

Blue: OII

Red: SI

Stages of Stellar Evolution

Fig. 19.6

Describe the stages (1-7) and lifetime of stellar evolution

Brief Summary of Stages of Stellar Evolution

Stage 1: interstellar cloud

Stage 2: Collapsing Fragment

Stage 3: Fragmentation Ceases

Stage 4: Protostar

Stage 5: Protostellar evolution

Stage 6: Newborn star

Stage 7: Main sequence star

Brief Summary of Properties of the Stages of Stellar Evolution

Table 19.1

Competing Forces in Collapses

Gravity causes collapse

Rotation, magnetism, and heat/radiation resist collapse

Fig. Chapter cover figure

Bok's globules

HR Diagram and Protostellar Evolution

Fig. 19.7

Stage 3-4: Kelvin-Helmholtz contraction phase

Hayashi Track occurs from stages 4-6

Stage 4-5: T-Tauri phase, often violent outbursts

M20: Evidence of Contraction

Fig. 18.20 and 19.9

Evidence of Stellar Formation

Fig. 19.11a disks in Orion region and Fig. 19.13a HH30, bipolar jet and protostellar disk

Shocks and Stellar Formation

Fig. 19.15

Shocks from emission nebula cause denser regions to further contract, cause 2^nd generation stars

Shocks move faster in less dense regions

Open and Globular Clusters

Name the type of stars represented in each HR diagram

Which cluster is younger and why? Fig. 19.18 and 19.19

Open and Globular Clusters

Open Cluster (Fig. 19.18) and Globular Cluster (Fig 19.19)

Summary: Star Formation

How do heat, rotation, and magnetism compete with gravity in cloud collapse

Phases of star formation: sequence leading to our Sun's formation

Mass, time, shocks

Evolutionary track of protostar on HR diagram

Observational evidence for star formation theory: cloud fragments, T Tauri protostars, HH objects, brown dwarfs

Zero age main sequence

Star clusters (open, associations, and globular): formation of, ages, locations, and types of stars