Term
| What is a planetary nebula and what type of star (i.e. low or high mass) produces it? |
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Definition
| a luminous shell of gas that is no longer gravitationally held to the remnant of a LOW MASS STAR |
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Term
| What is a white dwarf? How is it produced? Why is it stable? What type of star produces it? What is the range for white dwarf mass? (i.e. what is the Chandrasekhar limit?) |
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Definition
A. A low mass stellar remnant that has exhausted all its thermonuclear fuel & contracted to a size roughly equal to the size of the Earth
B. After main sequence burns out all its hydrogen & becomes red giant, star collapses into white dwarf
C. Electron degeneracy pressure
D. Main Sequence
E. as high as 1.4 M. (chandra limit) |
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Term
| What are the differences between a Type Ia and a Type II Supernova? (i.e. know how each is produced, what produces them, how the spectra are different, etc.) |
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Definition
Mass of WD in close binary exceeds 1.4 M. leading to explosion of star, no hydrogen lines in spectra.
Type II caused by the collapsing core of a star 8 M. or larger, when they begin fusing heavier & heavier elements until they start forming iron |
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Term
| What is a pulsar? What is a neutron star? How is it produced? What type of star produces it? What is the range for neutron star mass? |
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Definition
A. a pulsating source associated with a rapidly rotating neutron star star w/ an off axis magnetic field
B. remnants of a supernova explosion
C. Neutron star
D. 1.35-2.40 M. |
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Term
| What is a nova and how does it emit energy? |
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Definition
Only occur with WDs in close binary systems
Forms accretion disk as seen in picture
WD gets temporarily brighter
H fusion begins on surface of WD |
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Term
| What is a black hole? How is it produced? What type of star produces it? How do we detect stellar mass black holes? |
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Definition
A. An object whose gravity is so strong that the escape velocity from it exceeds the speed of light
B. When a main sequence more than 25 M. goes supernova and the matter collapses into itself
C. high mass stars above 25 M.
D. X-Ray |
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Term
| What is a singularity? What is the Schwarzschild radius? What is the event horizon? |
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Definition
A. A place of infinite curvature of spacetime in a blackhole, where the laws of physics do not apply
B. The distance from the center to the event horizon in any blackhole
C. The boundary between the black hole and the outside universe |
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Term
| How are intermediate black holes produced and where are they found usually? How are supermassive black holes produced and where are they found? |
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Definition
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Term
| What is an x-ray burster? What are the differences between an x-ray burster and a nova? |
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Definition
A. Neutron star “nova”
B. Helium fusion for XRB, H fusion for nova |
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Term
| What is a gamma ray burst and how do scientists think they are produced? |
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Definition
| A short burst of gamma rays; the source of the burss are outside our galaxy |
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