4.6

Question 1

Definition of a Nova

Answer 1

Nova = New star, referring to an exploding star.

Question 2

Peak Brightness of a Supernova

Answer 2

Peak brightness is in the range:

M_V ≈ -17^m to -19^m

Question 3

Visibility Duration of a Supernova

Answer 3

A supernova is visible for several weeks.

Question 4

Observation Wavelengths of Supernovae

Answer 4

Supernovae can be observed in many wavelengths.

Question 5

Type I Supernovae

Observational types

Answer 5

No hydrogen lines in the spectrum.

Question 6

Type Ia Supernovae

Answer 6

• Characterized by silicon lines
• Very homogeneous class
• produced by explosions of white dwarfs
• if white dwarfs of identical mass and under identical conditions then supernovae appear identical
• all Type Ia reach same max intrinsic luminosity and after luminosity decreases in same way

Question 7

Type Ib Supernovae

Answer 7

Characterized by strong helium lines.

Question 8

Type Ic Supernovae

Answer 8

Characterized by weak helium lines.

Question 9

Type II Supernovae

Answer 9

Hydrogen lines are present in the spectrum.
- believed to take place in much more massive stars
- core shrinks once run out of nuclear fuels
- shrinking suddenly stops when neutron deceneracy pressure balances gravity
- supernova caused by explosive bouncing off of the envelope surrounding newly formed neutron star core

Question 10

Long Gamma Ray Bursts

are associated with?

Answer 10

Associated with supernovae with relativistic jet.

Question 11

Short Gamma Ray Bursts

Answer 11

Associated with neutron star merger.

Question 12

Core Collapse Supernovae

Answer 12

Includes types II, Ib and Ic

Question 13

Degenerate Star Explosion

of which type is it?

Answer 13

Type Ia - Explosion of CO white dwarf.

Question 14

Neutron Star Merger

what does it cause?

Answer 14

Causes gravitational waves.

Question 15

Energy Generation in Core Collapse Supernovae

Answer 15

Collapse of 1.4 M_☉ iron core to 10 km yields ∼5⋅10⁴⁴ J.

Question 16

Neutrino Emission in Supernovae

Answer 16

About 99% of energy escapes as neutrinos.

Question 17

Supernova Nuclear Reactions

Answer 17

Complex nuclear reactions occur in the expanding shock front.

Question 18

Supernova Lightcurves

+ formula

Answer 18

• variation of supernoca luminosity with time
  Homogeneous fall-off observed:

L(t) ∝ 2^-t/77d
- copious amounts of 56Co produced in Type II and decay responsible for light curve

Question 19

Chemical Evolution of the Universe

Answer 19

Supernova lightcurves yield m(Fe) which is injected into space.
- elements heavier than iron are synthesized in Type II supernovae