Section 3: Stellar Spectroscopy and classification

Question 1

What is the key factor in emission and absorption lines?

Answer 1

Temperature

Question 2

How do high temperatures affect absorption lines?

Answer 2

At high T some elements are ionised and so have no absorption lines

Question 3

Why are He absorption lines found at high T?

Answer 3

He requires very high T to raise electrons from the ground state

Question 4

What are the main factors controlling line strength?

Answer 4

Excitation
Ionisation

Question 5

What is the probability to find an electron in a state?

Answer 5

P=e^-E₁/k_BT

Question 6

What is the Boltzmann equation?

Answer 6

N_B/N_A=g_B/g_A e^{-(E_B-E_A)/k_BT}