Solutions Manual – Stars and Stellar
Processes by Mike Guidry (All 22
Chapters)
How is dust formed? - answer-Dust forms mostly in giant stars through shocks that push gas
outwards, leading to the recombination of electrons into atoms, then molecules, and finally
dust grains.
Can we get distances from non-cluster stars? - answer-Yes, but they aren't as useful due to
unresolved binaries, uncertainty about main sequence status, and difficulties in accounting for
dust/reddening.
Why do we use clusters for measurements? - answer-Clusters have a fixed age and distance,
allowing for accurate measurements of apparent brightness and a reliable luminosity/flux
relation.
How does dust affect the CMD? - answer-Dust moves the CMD down and to the right,
mimicking an older age.
What is the erroneous age for identical star clusters aged 1 Gyr? - answer-To find the erroneous
age, compare luminosities with the apparent luminosity formula and work backwards.
How does the M/L ratio depend on star cluster age? - answer-Older star clusters have a larger
M/L ratio due to the loss of high luminosity, high mass stars, while younger clusters retain their
luminous stars.
1
, Where are stars and star clusters that formed before the galaxy? - answer-They are located in
the halo.
How is a spiral galaxy formed? - answer-A spiral galaxy forms when gas, dust, and young stars
fall into a rotating disk, creating a disk of ordered motions and a halo of disordered motion.
How would two stars of different temperatures and masses look on CMD? - answer-For
luminosities, use the M/L relationship; hotter stars are to the left on the CMD.
Why is the sky blue? - answer-The sky appears blue due to the scattering of blue light, which
has a shorter wavelength.
Why look at infrared vs optical? - answer-Infrared is preferred because dust is less important in
infrared than in visible wavelengths.
How does the metallicity difference between disk and halo fit into the origin story? - answer-
Gas in galaxies comes from the Big Bang and is recycled through stars, with solar abundances
primarily consisting of hydrogen and helium.
What is the life cycle of a star? - answer-Stellar evolution is largely determined by mass, with
significant phases including gravitational collapse, protostar formation, main sequence, and
post-main sequence evolution.
What happens during the protostar phase? - answer-The central temperature rises, and
hydrogen fusion begins at around 10⁷ K, lasting about 50 Myr for the Sun.
What occurs during the main sequence phase? - answer-Hydrogen fusion occurs, converting
0.7% of mass into energy, and the star reaches hydrostatic equilibrium.
2
Processes by Mike Guidry (All 22
Chapters)
How is dust formed? - answer-Dust forms mostly in giant stars through shocks that push gas
outwards, leading to the recombination of electrons into atoms, then molecules, and finally
dust grains.
Can we get distances from non-cluster stars? - answer-Yes, but they aren't as useful due to
unresolved binaries, uncertainty about main sequence status, and difficulties in accounting for
dust/reddening.
Why do we use clusters for measurements? - answer-Clusters have a fixed age and distance,
allowing for accurate measurements of apparent brightness and a reliable luminosity/flux
relation.
How does dust affect the CMD? - answer-Dust moves the CMD down and to the right,
mimicking an older age.
What is the erroneous age for identical star clusters aged 1 Gyr? - answer-To find the erroneous
age, compare luminosities with the apparent luminosity formula and work backwards.
How does the M/L ratio depend on star cluster age? - answer-Older star clusters have a larger
M/L ratio due to the loss of high luminosity, high mass stars, while younger clusters retain their
luminous stars.
1
, Where are stars and star clusters that formed before the galaxy? - answer-They are located in
the halo.
How is a spiral galaxy formed? - answer-A spiral galaxy forms when gas, dust, and young stars
fall into a rotating disk, creating a disk of ordered motions and a halo of disordered motion.
How would two stars of different temperatures and masses look on CMD? - answer-For
luminosities, use the M/L relationship; hotter stars are to the left on the CMD.
Why is the sky blue? - answer-The sky appears blue due to the scattering of blue light, which
has a shorter wavelength.
Why look at infrared vs optical? - answer-Infrared is preferred because dust is less important in
infrared than in visible wavelengths.
How does the metallicity difference between disk and halo fit into the origin story? - answer-
Gas in galaxies comes from the Big Bang and is recycled through stars, with solar abundances
primarily consisting of hydrogen and helium.
What is the life cycle of a star? - answer-Stellar evolution is largely determined by mass, with
significant phases including gravitational collapse, protostar formation, main sequence, and
post-main sequence evolution.
What happens during the protostar phase? - answer-The central temperature rises, and
hydrogen fusion begins at around 10⁷ K, lasting about 50 Myr for the Sun.
What occurs during the main sequence phase? - answer-Hydrogen fusion occurs, converting
0.7% of mass into energy, and the star reaches hydrostatic equilibrium.
2
