Astronomy Test 4 Flashcards
The three factors that determine internal pressure
Temperature, rotation, and magnetic fields
The 4 regions of star formation
- Cold regions in interstellar space (H1 regions)
- H2 regions
- Dark nebula
- Bok Globules
Lamda(emission of protons) = 21 cm due to the spin flip of the electrons in the hydrogen atom. what regions on the DR diagram does this occur?
H1 regions
Molecular hydrogen only forms in very cold regions but radiates very little. what regions on the DR diagram does this occur?
H2 regions
Small round nebula. What does this describe?
Bok Globules
A cloud of gas collapses by what?
Mutual gravitational attraction
How do gas clouds become dark nebulas?
Inner regions cool and further collapse after gravitational attraction
What happens after a gas cloud becomes a dark nebula
Internal temperatures and pressures rise and fight collapse
Since cooling can never be efficient enough to reduce the internal pressure enough according to current theories “something” causes further collapse. What is it?
Shockwaves
Where do shockwaves come from? (3 things)
Newly formed stars, supernova explosions, and galactic spiral arms
Further collapse of cloud fragments from dark nebula’s become small, round what?
Bok Globules
Globules further collapse and form what?
Proto-stars
After 1000’s of years a proto-star becomes a star and appears on the ______ on the H-R diagram
Birthline
Dust that surrounds a proto-star and absorbs light
Cocoon nebula
Problems with star formation?
How does a single,isolated star not in a spiral galaxy form? And what if there’s no shocks around?
In the death of low mass stars, Helium fuses to ____ at _______K
Carbon, 100,000,000 Kalvin
In the death of low mass stars, as H is depleted in the core, the core collapses and heats up a H shell around the core and begins to burn and envelope expands. What stage is this?
Red Giant
In the death of low mass stars, the core continues to collapse until T= 100,000,000K. Helium burns explosive because of what?
Quantum degeneracy (all He is at the same temperature)
In the death of low mass stars, outer layers are blown off into interstellar space (planetary nebula) and hot, solid cargo core becomes a ______
White dwarf
In the death of high mass stars, what is the onion skin model. (6 layers)
- H to He
- He to Carbon
- C to Magnesium and Neon
- N to Mg and O
- O to silicon
- S to Fe
In the death of high mass stars, as outer layers crash onto the core, the envelope material is blown off and a _______ results.
Supernova
In the death of high mass stars, if core mass is less than 1.4 then the core remnant is a
White dwarf
In the death of high mass stars, if core mass is greater than 1.4 then the core remnant becomes a
Neutron star
In the death of high mass stars, if core mass exceeds about 3, then the core remnant becomes a
Black hole
