← AST 309N Test 2 Test
5 Written Questions
5 Matching Questions
- Type Ia
- Neutron Star
- Jet-induced explosions
- 2nd way a core collapse of the outer layers of a star may occur
- Type Ic Supernovae
- a no hydrogen, little or no helium early on, O, Mg, Ca later. Occur in spiral arms, never in
elliptical galaxies. Massive star core collapse
- b Supercomputer computations show that sufficiently powerful jets can blow up a star.
The jets plow up and down along one axis creating a "breadstick" shape and driving bow shocks. The bow
shocks propagate away from the jets toward the equator where they collide. The result of this collision is to blow
much of the star out along the equator in a torus or "bagel" shape. The final configuration is far from spherical,
but has jets in one direction and a torus expanding at right angles to the jet.
- c mass of Sun, but size of a small city. Huge density, surface gravity. Maximum mass of about 2
- d Delayed mechanism: Neutrinos stirred out by the boiling neutron star deposit heat behind the standing
shock and reinvigorate it. Not clear this is sufficient
- e must generate explosion in old (1 to 10 billion years) stellar system. Most plausible mechanism mass
transfer onto white dwarf.
5 Multiple Choice Questions
- Most massive star of close pair evolves first, fills its Roche lobe and some of its mass begins to
leak through inner Lagrangian point to the companion star
- spherical. They may be "breadstick"
shaped or "bagel" shaped or some combination of elongation and flattening.
- similar to Type Ia, but dimmer at maximum brightness.
- about 100 times more energy than needed to create an
explosion, but most of that energy is carried off by neutrinos.
- Prompt mechanism: The neutron star rebounds, driving a shock wave into the outer parts of the star.
The bounce shock occurs, but is insufficient to cause an explosion
5 True/False Questions
Inner Lagrangian Point → the outer parts of disks typically have temperatures comparable to the Sun and shine with
optical light. Middle parts are hotter and glow in ultraviolet light. This is appropriate for white dwarfs. The
innermost parts can be hot enough to emit X-rays. This is appropriate to neutron stars and black holes.
Type Ib Supernovae → no hydrogen, but observe helium early on, O, Mg, Ca later. Occur in spiral arms, never in
elliptical galaxies. Massive star core collapse.
Algol Paradox → must generate explosion in old (1 to 10 billion years) stellar system. Most plausible mechanism mass
transfer onto white dwarf.
Final evolution of cataclysmic variables → system consisting of a white dwarf receiving mass via an accretion disk from a
companion, frequently a small mass main sequence star.
What halts the collapse and allows the neutron star to form? → Repulsive nuclear force between highly compressed neutrons and neutron quantum pressure