ASP Stellar Astronomy and Star Life Cycles 2 — Questions and Answers
Question 1: What is a pulsar?
- A variable star that pulses thermally
- A rapidly rotating neutron star emitting beams of electromagnetic radiation (Correct answer)
- A type of binary star system
- A star in the final stage before going supernova
Correct answer: A rapidly rotating neutron star emitting beams of electromagnetic radiation
A pulsar is a highly magnetized, rapidly rotating neutron star that emits beams of electromagnetic radiation from its magnetic poles, detected as regular pulses when the beam sweeps past Earth.
Question 2: What stellar spectral class is the Sun?
- A
- F
- G (Correct answer)
- K
Correct answer: G
The Sun is a G-type (G2V) main-sequence star, characterized by a surface temperature around 5,500°C and a yellow-white color.
Question 3: What is the CNO cycle in stellar physics?
- Carbon-Nitrogen-Oxygen fusion cycle used by massive stars to fuse hydrogen (Correct answer)
- A process of carbon, nitrogen, and oxygen absorption in stellar atmospheres
- The cycle of stellar wind carrying these elements into space
- The cooling cycle of post-main-sequence stars
Correct answer: Carbon-Nitrogen-Oxygen fusion cycle used by massive stars to fuse hydrogen
The CNO (Carbon-Nitrogen-Oxygen) cycle is a series of nuclear reactions in which carbon, nitrogen, and oxygen act as catalysts to fuse hydrogen into helium, dominant in stars more massive than the Sun.
Question 4: What is the event horizon of a black hole?
- The disk of material spiraling into the black hole
- The boundary beyond which nothing can escape the black hole's gravity (Correct answer)
- The region of intense radiation surrounding a black hole
- The point of infinite density at the black hole's center
Correct answer: The boundary beyond which nothing can escape the black hole's gravity
The event horizon is the spherical boundary around a black hole at the Schwarzschild radius, inside which the escape velocity exceeds the speed of light and nothing—including light—can escape.
Question 5: What type of supernova results from the thermonuclear explosion of a white dwarf?
- Type II
- Type Ib
- Type Ia (Correct answer)
- Type Ic
Correct answer: Type Ia
Type Ia supernovae occur when a white dwarf accretes enough mass from a binary companion to exceed the Chandrasekhar limit, triggering a thermonuclear explosion that destroys the entire star.
Question 6: What is a brown dwarf?
- A star that has burned out
- A substellar object too massive to be a planet but too small to sustain hydrogen fusion (Correct answer)
- A type of neutron star
- A red giant that has cooled
Correct answer: A substellar object too massive to be a planet but too small to sustain hydrogen fusion
Brown dwarfs are substellar objects with masses between about 13 and 80 Jupiter masses—too massive to be planets but lacking sufficient mass to sustain hydrogen fusion like true stars.
ASP Stellar Astronomy and Star Life Cycles 2
What is a pulsar?