Due Date: Mar. 17, 2008
Instructions: Print and complete the following homework assignment. Make sure you write your name on the paper.
Name: ________________________________________
Circle whether each statement is True or False (1 pt each).
The color of a star tells us its temperature. True False
The apparent magnitude of a star tells us the star's luminosity. True False
Listed from hottest to coldest, the spectral types are O, B, A, F, G, K, and M. True False
In a spectroscopic binary system we can tell the velocity of one of the stars by looking the doppler shift of its spectral lines. True False
The Sun is classified as a G2 II star. True False
Stars spend most of their lifetimes on the Main Sequence. True False
We can determine the age of a star cluster by looking at it main-sequence turnoff point. True False
Astronomers consider all elements heavier than hydrogen to be metals. True False
Astronomers use infrared light to see through star-forming clouds. True False
A typical star-forming cloud has enough mass to form many stars. True False
All protostars fuse hydrogen. True False
Brown dwarfs are white dwarfs that have cooled. True False
Most stars are roughly the same mass as the Sun. True False
All of the elements were created in the Big Bang. True False
Helium fusion creates carbon. True False
Carbon stars are on the main sequence. True False
Planets form from planetary nebulae. True False
High-mass stars fuse hydrogen via the p-p chain. True False
Supergiants can fuse neon to produce energy. True False
A nova might leave behind a neutron star. True False
All neutron stars are pulsars. True False
Fill in the blanks (2 pts each).
The total amount of power that a star emits into space is called _____________.
A _________________ binary is a pair of stars that we can see distinctly (with a telescope) as the stars orbit each other.
The horizontal axis of an H-R diagram indicates the stars____________________ .
_____________________ is a star's most fundamental property.
Most stars form in __________________ .
The two types of clusters are ___________________ clusters and globular clusters.
Apparent brightness follows an inverse _______________ law with respect to distance.
Stars form from __________________ clouds.
The final stage in the birth of a star is ___________________ fusion.
The minimum mass of a star is approximately-_______________ MSun.
The maximum mass of a star is approximately _______________ MSun.
After depleting all of the hydrogen in its core a star will produce energy via hydrogen __________________ burning.
Two silicon nuclei can fuse together to form an ________________________ nucleus.
A proton and an electron can combine to form a _______________ and a neutrino.
Elements heavier than iron were formed by _________________________ .
When a white dwarf fuses helium it becomes a ________________.
X-Ray Binaries are close binaries that contain accreting _______________ stars.
Calculate (attach a separate sheet for the answers in this section) each of the following. Show all of your work. Note that you must explicitly write the correct units for each problem. (10 pts each).
The minimum mass of a star-forming cloud that has a particle density of 10,000,000 particles per cubic meter, and a temperature of 10 K.
The temperature of a white dwarf that has a radius of 6,000 km and a luminosity of 0.1 LSun.
The density of a neutron star with a radius of 10 km and a mass that is twice that of the Sun.
The minimum and maximum apparent brightness of an eclipsing binary system consisting of one star with an apparent brightness of A and a second star with an apparent brightness of B.
How would the brightness of a nova 20 ly away compare to the brightness of the Sun?
The Crab Nebula was formed by supernova approximately 1,000 years ago. The nebula is 40 ly across. Assuming that the gas in the outermost parts of the nebula have been moving at a constant velocity for past 1,000 years, what is the velocity of the gas (express your answer in meters per second)?