Surface Temperatures – Astronomy Quiz 5
The key terms of Astronomy Quiz include, Cepheid Variable, Surface Temperatures.
According to Henrietta Swan Leavitt, the Cepheid variable stars obeyed a beautiful relationship that allowed them to be used as “Standard Candles”. Which of the following qualitatively describes that relationship?
The longer the period, the larger the luminosity.
The hottest main sequence stars also have the greatest masses. Why do the greatest mass stars also have the highest surface temperatures?
The greater the mass of the star, the greater the pressure and temperature at the core, resulting in a greater fusion rate. The greater fusion rate releases more energy which results in hotter surface temperature.
Which kind of interstellar medium is primarily ionized and emits Ha radiation?
H II regions.
What is the net result of the CNO cycle?
Four hydrogen nuclei are transformed into one helium nucleus, two neutrinos, two positrons and energy(including photons).
Which type of star is the most common type of star in the Milky Way (and probably in the Universe)?
M class stars
What happens when a neutron decays outside the nucleus? Which particles do we see emerge from the decay process?
It forms a pair of particles; one proton and one electron.
The last solar maximum (maximum sunspot activity) occurred in 2014. When would you expect the next solar maximum to occur?
2025
James Kaler studied symbiotic binary star systems that consisted of a red giant and a white dwarf star. These systems would light up periodically (but not a regular time intervals) with a flash of light called a Nova. What caused the Nova to occur?
The white dwarf recieves matter from the outer layer of the red giant. When the matter hits the white dwarf surface it fuses and releases energy very quickly in a Nova.
Which of the following statements correctly describes the “free-fall” time for a developing protostar? (
Small mass protostars have very long free-fall times because the force of gravity is weaker.
Large mass protostars have short free-fall times because the force of gravity is stronger.
The free-fall time is the period when gravity is pulling the cloud of gas together but there is not yet a large radiation pressure to slow and stop the process.
A star with a mass of 100Msun is predicted to live on the main sequence for
100 thousand years
Which of the following stellar properties increases as you follow the main sequence from the right side to left sideof the HR diagram?
All
How does the metallicity of a young star compare to that if a much older star found in the same region of the galaxy?
the young star will have a higher metallicity than the older star, indicating it has been enriched by stars that lived before it.
An astronomer observes a globular cluster of stars and constructs an HR diagram like the figure below. What can they learn by identifying the spectral class of the region marked “X”?
the age of the cluster.
The sun is a large incandescent (which means that it shines with light from the heat) ball of mostly hydrogen and helium _______________.
plasma
Interstellar reddening occurs when the light of a star passes through a dust cloud. The dust absorbs some of the shorter wavelength light, making the star look
redder and dimmer
The diagram below shows our sun at some point in its life. What do we call the sun at the stage shown?
red giant.
Although astronomers do not understand everything about jets that are emitted from protostellar disks, the fact that there are two of them and that they are aligned with the axis of rotation tells us they are related to
the magnetic field generated by the dynamo effect in the accretion disk.
According to Henrietta Swan Leavitt, the Cepheid variable stars obeyed a beautiful relationship that allowed them to be used as “Standard Candles”. Which of the following qualitatively describes that relationship?
The longer the period, the larger the luminosity.
The hottest main sequence stars also have the greatest masses. Why do the greatest mass stars also have the highest surface temperatures?
The greater the mass of the star, the greater the pressure and temperature at the core, resulting in a greater fusion rate. The greater fusion rate releases more energy which results in hotter surface temperature.
Which kind of interstellar medium is primarily ionized and emits Ha radiation?
H II regions.
What is the net result of the CNO cycle?
Four hydrogen nuclei are transformed into one helium nucleus, two neutrinos, two positrons and energy(including photons).
Which type of star is the most common type of star in the Milky Way (and probably in the Universe)?
M class stars
What happens when a neutron decays outside the nucleus? Which particles do we see emerge from the decay process?
It forms a pair of particles; one proton and one electron.
The last solar maximum (maximum sunspot activity) occurred in 2014. When would you expect the next solar maximum to occur?
2025
James Kaler studied symbiotic binary star systems that consisted of a red giant and a white dwarf star. These systems would light up periodically (but not a regular time intervals) with a flash of light called a Nova. What caused the Nova to occur?
The white dwarf recieves matter from the outer layer of the red giant. When the matter hits the white dwarf surface it fuses and releases energy very quickly in a Nova.
Which of the following statements correctly describes the “free-fall” time for a developing protostar? (
Small mass protostars have very long free-fall times because the force of gravity is weaker.
Large mass protostars have short free-fall times because the force of gravity is stronger.
The free-fall time is the period when gravity is pulling the cloud of gas together but there is not yet a large radiation pressure to slow and stop the process.
A star with a mass of 100Msun is predicted to live on the main sequence for
100 thousand years
Which of the following stellar properties increases as you follow the main sequence from the right side to left sideof the HR diagram?
All
How does the metallicity of a young star compare to that if a much older star found in the same region of the galaxy?
the young star will have a higher metallicity than the older star, indicating it has been enriched by stars that lived before it.
An astronomer observes a globular cluster of stars and constructs an HR diagram like the figure below. What can they learn by identifying the spectral class of the region marked “X”?
the age of the cluster.
The sun is a large incandescent (which means that it shines with light from the heat) ball of mostly hydrogen and helium _______________.
plasma
Interstellar reddening occurs when the light of a star passes through a dust cloud. The dust absorbs some of the shorter wavelength light, making the star look
redder and dimmer
The diagram below shows our sun at some point in its life. What do we call the sun at the stage shown?
red giant.
Although astronomers do not understand everything about jets that are emitted from protostellar disks, the fact that there are two of them and that they are aligned with the axis of rotation tells us they are related to
the magnetic field generated by the dynamo effect in the accretion disk.