ASP Stellar Astronomy and Star Life Cycles 1 — Questions and Answers
Question 1: What is the Hertzsprung-Russell (H-R) diagram used to show?
- The positions of planets in the solar system
- The relationship between stellar luminosity and temperature (Correct answer)
- The orbital velocities of binary stars
- The distribution of galaxies in the universe
Correct answer: The relationship between stellar luminosity and temperature
The H-R diagram plots stellar luminosity versus surface temperature, revealing that stars fall into distinct groups including the main sequence, giants, supergiants, and white dwarfs.
Question 2: What powers a main-sequence star like the Sun?
- Gravitational contraction
- Chemical combustion
- Nuclear fusion of hydrogen into helium (Correct answer)
- Nuclear fission of uranium
Correct answer: Nuclear fusion of hydrogen into helium
Main-sequence stars are powered by nuclear fusion reactions in their cores, converting hydrogen into helium and releasing enormous amounts of energy via E=mc².
Question 3: What stellar remnant is left after a low-mass star like the Sun ends its life?
- Neutron star
- Black hole
- White dwarf (Correct answer)
- Brown dwarf
Correct answer: White dwarf
After exhausting its nuclear fuel and shedding its outer layers as a planetary nebula, a low-mass star leaves behind a dense, hot white dwarf composed mainly of carbon and oxygen.
Question 4: What is a neutron star?
- A star made entirely of hydrogen
- An ultra-dense stellar remnant composed mainly of neutrons (Correct answer)
- A failed star that never ignited fusion
- A star with no detectable magnetic field
Correct answer: An ultra-dense stellar remnant composed mainly of neutrons
A neutron star is an extremely dense stellar remnant formed from the collapsed core of a massive star after a supernova, with densities so extreme that protons and electrons merge into neutrons.
Question 5: What is the Chandrasekhar limit?
- The maximum temperature a star's core can reach
- The maximum mass (~1.4 solar masses) a white dwarf can have before collapsing (Correct answer)
- The minimum mass required for nuclear fusion to begin
- The maximum size of a neutron star
Correct answer: The maximum mass (~1.4 solar masses) a white dwarf can have before collapsing
The Chandrasekhar limit (~1.4 solar masses) is the maximum mass a white dwarf can support against gravitational collapse; exceeding it leads to a Type Ia supernova.
Question 6: What is a stellar parallax used to measure?
- A star's surface temperature
- A star's distance from Earth (Correct answer)
- A star's proper motion
- A star's luminosity class
Correct answer: A star's distance from Earth
Stellar parallax measures the apparent shift in a star's position against background stars as Earth orbits the Sun, allowing astronomers to calculate the star's distance using trigonometry.
ASP Stellar Astronomy and Star Life Cycles 1
What is the Hertzsprung-Russell (H-R) diagram used to show?