ISM Flashcards
1
Q
gas can cool
A
2
Q
density high enough,
A
3
Q
any diffuse gas hard to cool below 10^4 K
A
4
Q
hydrogen only has one ion
A
one peak
5
Q
cooling curve per element
A
6
Q
below 10^4
A
fine structure lines and molecules dominate cooling
7
Q
cooling below 10^4 K
A
only possible if H_2 (molecular) is present
8
Q
beyond 10^4 K
A
Ly-alpha comes into play, increase gas density helps total cooling
9
Q
10^4-6K
A
K-shell and L-shell dominate
10
Q
10^6-7K
A
Iron lines dominate
11
Q
> 10^7K
A
free-free interaction helps cool down, thermal bremmstrahlung
12
Q
cooling rate depends on density
A
13
Q
NII is right next to H-alpha
A
14
Q
He II, 1640
A
he balmer line, 54 eV
