AST Exam 3
In comparison to elliptical galaxies, spiral galaxies: Contain mostly younger stars (but can contain some older ones). Appear more blue. None of the listed choices. Exhibit star formation. All of the listed choices.
All of the listed choices.
In comparison to elliptical galaxies, spiral galaxies:All of the listed choices. Appear more blue. Contain mostly younger stars (but can contain some older ones). None of the listed choices. Exhibit star formation.
All of the listed choices.
In comparison to spiral galaxies, elliptical galaxies: Appear more red. All of the listed options. Exhibit no star formation. Contain mostly older stars. None of the listed options.
All of the listed options
In comparison to spiral galaxies, elliptical galaxies:None of the listed options. Contain mostly older stars. All of the listed options. Exhibit no star formation. Appear more red.
All of the listed options.
A proposed explanation for gamma-ray bursts is:
Hypernovae that can make black holes and bi-polar jets.
A star is on the horizontal branch of the HR diagram. Which statement is true?
It is burning both hydrogen and helium.
In stellar evolution, what is the significance of the temperature 100 million K?
It is the temperature at which helium fusion can begin.
At which stage in a Sun-like star's life is its core the least dense?
Main Sequence
Which of the following is NOT a characteristic of an elliptical galaxy?
Ongoing star formation
Which of the following lists, in the correct order, a possible evolutionary path for a star?
Red Giant, Planetary Nebula, White Dwarf
Mass transfer in binary systems occurs when one giant swells and exceeds its:
Roche Lobe
The Milky Way is often considered to be an intermediately wound, barred spiral, which would be type ________ according to Hubble.
SBb
The radius at which the escape speed from a black hole equals the speed of light is the:
Schwarzschild radius
Which of the following is true regarding planetary nebulae?
Some are spherical, but many are irregularly shaped.
Which galaxies appear mostly blue?
Spiral
Which galaxies appear to have many young stars?
Spiral
Which galaxies are likely to contain both O-spectral type stars as well as M-spectral type stars?
Spiral
Which galaxies contain abundant amounts of gas and dust?
Spiral
What is one of the differences between Cepheids and RR Lyrae variables?
The RR Lyrae stars have much shorter periods than Cepheids.
Isolated main sequence stars as massive as 10 - 12 times the mass of the Sun might manage to avoid going supernova. Why?
They can have strong stellar winds which cause much mass loss.
A recurrent nova could eventually build up to be a:
Type I supernova
What is the nearest huge cluster of galaxies to our Local Group?
Virgo Cluster
Which of these does NOT depend on a close binary system to occur?
a Type II supernova
A hypernova probably creates:
a long-duration gamma ray burst
The greater a galaxy's redshift, the:
farther it is from us.
For elements heavier than iron, energy can only be produced:
fission of heavy elements back toward lighter ones
For a white dwarf to become a nova it is necessary for it to:
have a binary companion.
In the Lighthouse Model:
if the beam sweeps across us, we will detect a pulse of radiation.
When a star's inward gravity and outward pressure are balanced, the star is said to be:
in hydrostatic equilibrium.
Which is the correct description of the Sun's location within the Milky Way?
in the disk and about two-thirds of the galactic radius from the center
The region on the H-R diagram where pulsating variables occur is called the:
instability strip
An iron core cannot support a star because:
iron cannot fuse with other nuclei to produce energy
What can you conclude about a Type I supernova?
it was originally a low mass star
In neutronization of the core, a proton and an electron make a neutron and a(n):
neutrino
An object more massive than the Sun, but roughly the size of a city, is a:
neutron star
A surface explosion on a white dwarf, caused by falling matter from the envelope of its binary companion, creates a:
nova
Compared to a cluster containing O and B type stars, a cluster with only F type and cooler stars will be:
older
Refer to the figure below. What is the name of the path between the points labeled 11 and 12? HR with Stell Evol.png
planetary nebula
Which of these will the Sun probably become in the very distant future?
planetary nebula
Two important properties of young neutron stars are:
rapid rotation and a strong magnetic field
Refer to the figure below. What is the name of the path between the points labeled 8 and 9? HR with Stell Evol.png
red giant branch
Pulsars:
spin very rapidly when they are young.
Most of the new star formation in the Galaxy is found in the:
spiral arms
Black holes are formed by:
supernovae from the most massive stars.
What is one of the differences between Cepheids and RR Lyrae variables?
the RR Lyrae stars have much shorter periods than Cepheids.
What is a planetary nebula?
the ejected envelope of a red giant surrounding a stellar core remnant
Which galaxy would you expect to have many young, bright stars?
the one that looks blue
What observations suggest the mass of the Galaxy goes much farther out than its visible disc?
the rotation curve of the outermost portions of the disc
Density waves may explain:
the spiral arm structure of the Galaxy
During the hydrogen burning shell phase: Correct!
the star grows more luminous.
Neutron stars and black holes are formed by:
type II supernovae
The order of evolutionary stages of a star like the Sun would be main sequence, red giant, planetary nebula, and finally:
white dwarf
Our Sun will not become a nova because this only happens to stars:
with a binary companion
The RR Lyrae stars all have periods of:
0.5 - 1 day
The Chandrasekhar limit is:
1.4 solar masses
What temperature is needed to fuse helium into carbon?
100 million K
The supernova that formed M-1, the Crab Nebula, was observed in:
1054 AD by Chinese and Middle Eastern astronomers.
The minimum mass of the progenitor star required to form a black hole is probably:
25 solar masses
Refer to the figure below. At what numbered point on the graph does the helium flash occur?
9
Which galaxies contain old stars?
Both
A proposed explanation for gamma-ray bursts is:
Coalescence of a neutron star binary.
Which of the following is NOT a characteristic of a spiral galaxy?
Contains little gas and dust
The most elongated of the ellipticals are:
E7
Contains little gas and dust
Elliptical
Which galaxies are likely to contain many M-spectral type stars but no O-spectral type stars?
Elliptical
In this diagram, the galaxy at the left side is a(n)
Elliptical galaxy
Noting the mass of the main sequence turnoff stars in a star cluster allows you to determine its:
age
A star (no matter what its mass) spends most of its life:
as a main sequence star.
Detailed measurements of the disk and central bulge region of our Galaxy suggest our Milky Way is a:
barred spiral galaxy
The eventual fate of our Sun is to:
become a steadily cooling white dwarf.
The heaviest nuclei of all are formed:
by neutron capture during a type II supernova explosion.
