Astronomy Module 13
Which of the following pairs of main sequence stars have different endpoints for their lives as stars?
10 and 5 solar mass stars
Which of the following foods does not describe a possible way to die from a Black Hole?
Chicken Wings
Rank the following stages of evolution or events in the life of a solar mass star like the Sun from earliest to latest.
Earliest protostar main sequence red giant helium flash horizontal branch AGB star planetary nebula white dwarf Latest
Which statement accurately describes a neutron star?
It is an object that results from the death of a massive star.
Why have we not observed the end of the life cycle for the smallest mass stars?
None have come to the end of their life cycle.
Sort the following characteristics by whether they describe novas, Type Ia supernovas, or Type II supernovas.
Nova: powered by surface fusion periodic flares in brightness Type Ia Supernova: used as standard candles powered by fusion throughout the star come from the 1.4 Msun white dwarfs Type II Supernova: powered by gravity release the heaviest elements happen when massive stars
Set up the Interactive to run a simulation for a 1-solar-mass star and a 0.1-solar-mass star. Then "Start Playback." The simulation could take a few minutes to run. As it is running, notice that the two bars on the left-hand side advance upward, showing elapsed time. The time steps get larger as the simulation advances. When the bars are roughly halfway to the top, the stars have reached the main sequence. Identify the properties of the 0.1-solar-mass star versus the 1-solar-mass star.
Property of... 0.1-Solar-Mass Star: redder has longer main-sequence lifetime 1-Solar-Mass Star: hotter evolves more quickly varies in temperature more as it evolves Both Stars: changes luminosity as it evolves changes temperature as it evolves
Rank the following white dwarfs by their radius, from smallest to largest, using the information provided and the chart above. Do not include in your ranking any white dwarfs that cannot physically exist.
Smallest: white dwarf with 0.005 Rsun white dwarf with 1 Msun white dwarf with 0.01 Rsun white dwarf with 0.1 Msun Largest Not included: white dwarf with 1.6 Msun
What happens when a massive star's core becomes iron?
The star can no longer support itself against gravity.
Why does a red giant fuse hydrogen more rapidly than a main sequence star of the same mass?
The star's interior heats up.
Which of the following statements about white dwarfs is true?
They first appear at the center of a planetary nebula.
Label the places on the HR diagram where one would find the different phases of stellar evolution for a solar-mass star.
Top Middle: Planetary nebula Top Right: asymptotic giant branch Top Farthest-Right: helium flash Middle: horizontal branch Right Middle: red giant branch Lower Middle: main sequence Bottom Left: white dwarf
Label the Messier objects by the type of object to the left of the label.
Top Right: globular cluster Middle Left: star-forming nebula Middle Right: planetary nebula Bottom Left: spiral galaxy
A pulsar is also
a neutron star.
Which of the following is closest in radius to a neutron star?
a small city
What kind of remnant will a 100 MSun star leave?
black hole
Which of the following sets of measurements CANNOT be used to determine a main sequence star's eventual fate?
color and composition
A star is determined to be burning helium into carbon in a shell above its core. What mass star can it be?
either intermediate-mass or massive
A star is on the horizontal branch of the HR diagram. Which of the following describes nuclear fusion within the star?
helium to carbon in the core; hydrogen to helium in the first shell
Which of the following accurately describes changes to a star when it first moves off the main sequence of the HR diagram?
increased radius and decreased surface temperature
High-mass stars are able to reach the high temperatures needed to fuse carbon into heavier elements, which they do after the helium in their cores has been exhausted. After the carbon is used up, the core collapses and becomes hot enough to fuse the next heaviest element, and so forth. At the same time, concentric shells surrounding the core burn successively lighter elements in layers reminiscent of the layers of an onion, as shown in this figure. Think about how you would expect the temperatures in the star to vary between each of the layers shown, and use this to sort the following elements in order of increasing temperature at which they burn in a nuclear fusion reaction.
lowest temperature H He C Ne O S highest temperature
Which of the following determines the rate at which a star generates energy in its core?
mass
An isolated star's eventual fate is ultimately determined by its:
mass.
A star is 10 billion years old. What final form may it take when it dies?
only a white dwarf
Which of the following phases lasts for the shortest time as a massive star evolves?
silicon burning
Uranium in the Universe is produced in:
supernova explosions.
In order from most to least common, what are the possible remnants of stars that run out of fuel for fusion?
white dwarf, neutron star, black hole
The Sun will end its life as a:
white dwarf.
What supports a white dwarf star against gravity?
electron degeneracy pressure
Which force or process is primarily responsible for creating a black hole?
gravity
