Spectroscopy

Question 1

What do broad line features on the continuum show?

Answer 1

Speed at which the supernovae is moving.

Question 2

What occurs in the photospheric phase of spectra?

Answer 2

At early times and so high densities the photons can’t easily diffuse out through the ejecta.

Question 3

What occurs in the nebular phase of specta?

Answer 3

At late times and so low densities, energy is deposited in the ejecta and the created photons can immediately leave the ejecta.

Question 4

Why do different elements absorb different wavelengths as ejecta expands?

Answer 4

As the ejecta are expanding with a range of velocities, a photon with a given wavelength will only come into resonance with an atomic transition if the Doppler shift is just right.