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Astro Exam 5

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The dust that extends throughout the disk of the Galaxy only allowed Herschel to see the small part of it that is all around us.
William Herschel thought that the Sun and Earth were roughly at the center of the great group of stars we call the Milky Way. Today we know this is not the case. What was the reason that Herschel did not realize our true position in the Milky Way?
1)expressed a relationship between a Cepheid's luminosity and its period of pulsation
2)used a Cepheid to find the distance to the Andromeda Galaxy
3)stated a simple rule for relating a galaxy's velocity of recession to its distance
4)observed and categorized many other galaxies
Which of the following describe the astronomical work done by Edwin Hubble?
coplanar, circular orbits, population I, relatively high metallicities (~3%), may be low-mass stars, may be high-mass stars
Which of the following describe stars in the disk?
located in the disk, have stars with high metallicities (~3%), younger than a billion years, contain hundreds of stars on average
Which of the following describes open clusters?
open cluster
spiral
Our Milky Way is what type of galaxy?
All RR Lyraes have pretty much the same absolute magnitude
RR Lyrae Stars are useful as distance indicators because
Cepheids obey a period-luminosity relationship
Cepheid variable stars are useful as distance indicators because
halo stars (having lower metallicity) are older
What is the implication of the metallicity difference between the halo and disk stars?
We are in the disk of the Galaxy, about 5/8 of the way from the center
What have we learned from the work of Harlow Shapley and others about the location of the Sun in the Milky Way Galaxy?
Stars in the outskirts of the Milky Way orbit the galaxy at much higher speeds than we would expect if all the mass were concentrated in the disk
How do we know that there is much more mass in the halo of our galaxy than in the disk?
calculate the mass interior to that star's orbit
One can use a data point in the Milky Way Galaxy's rotation curve to ...
The far left of the following graph illustrates ...
the high orbital velocities of stars near the black hole at the center of our galaxy
in the spiral arms
Where does most star formation occur in the Milky Way today?
Approximately how far is it from the white circle to the center of the Milky Way Galaxy?
25,000 light years
Approximately how large is the diameter of the white dot?
10,000 light years
Local Group, Galaxy, Nebula, Star
Which of the following correctly lists objects from largest to smallest?
elliptical
Most of the galaxies that exist in the universe are
spiral
most of the galaxies that we see are
spiral
If a galaxy is seen to have many young and hot stars and fewer old stars it is most likely what kind of galaxy?
elliptical
What kind of galaxy tends to have very little gas and dust?
E5
On a CCD frame an elliptical galaxy has a long axis of 60 pixels and a short axis of 30 pixels. It would best be classified as ...
the one that is farthest away
Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time,which galaxy in the picture is the youngest?
10:08 PM.
Your satellite orbits close to the Sun and detects a solar flare erupting at 10:00 PM, as measured by the satellite�s clock.Your clock is exactly synchronized with the satellite clock. The Sun is located 8 light minutes away from Earth.If you wish to observe this flare from your backyard, you need to look at:
The person that is farther from you is actually the older of the two people.
Imagine that you simultaneously receive the satellite transmission of two pictures of two people that live on planets orbiting two different stars.Each image shows the people at their 21st birthday parties. Consider the following possible interpretations that could be made from your observations.Which do you think is the most plausible interpretation?
5,000
If H0 equals 50 km/sec-Mpc, then a galaxy at a distance of 100 Mpc probablyhas a recessional velocity of ...
The universe does not have a center
According to modern ideas and observations, what can be said about the location of the center of our expanding universe?
The distance between the two stars is unaffected
If our universe is expanding, what are the implications for the separation between two stars within our galaxy?
For an observer in Galaxy B, which of the following rankings lists the speeds (from fastest to slowest) at which Galaxies C, D, and E would be moving away?
D > C > E
Which of the following conclusions can you draw about the expansion of the universe fromthe drawing shown?
All galaxies appear to move away from each other during the expansion of the universe
matter falling toward a supermassive black hole at the center of a galaxy
Today, astronomers find compelling evidence that the energy source of the quasars and active galaxies is ..
far away
All quasars have large redshifts. This implies that they are ...
small
Some quasars demonstrate rapid fluctuations in brightness. This implies that they are ...
can be formed by galaxies as they bend the light from distant quasars
Gravitational lenses ...
the universe is uniformly distributed at large scales
What is meant when we say the universe is homogeneous?
the universe looks the same no matter which direction we look
What is meant when we say the universe is isotropic?
The diagram below illustrates Hubble's Law assuming that H0=65 km/sec-Mpc and shows the observed velocities of several galaxies.What would be the observed velocity of the Milky Way Galaxy as seen from the Alien's galaxy (galaxy C)?
1950 km/sec-Mpc
White-dwarf supernovae are so bright that they can be detected even in very distant galaxies, they are common, White-dwarf supernovae have very similar light curves, which make them easy to distinguish from massive-star supernovae
What makes white-dwarf supernovae good standard candles?
A Type IA supernova peaks with an apparent magnitude of 6.5. How far away is it?
16 Mpc
incredibly dense
According to the Big Bang model, what was the density of the universe like at its inception?
incredibly hot
According to the Big Bang model, what was the temperature of the universe like at its inception?
it got cooler and less dense
According to the Big Bang model, as the universe expanded what happened?
it speeds the expansion up
What tends to be the influence of dark energy on the expansion of the universe?
recombination
What stage refers to the period when electrons could finally stick to a proton without ionizing again straight away?
in the first few minutes of the big bang
Elements with small nuclei (hydrogen through berrylium) were created by nuclear reactions
in the cores of stars
Elements with medium sized nuclei (those from carbon up to iron) were created by nuclear reactions
in supernovae explosions
Elements with massive nuclei (those bigger than iron up to lead) were created by nuclear reactions
globular clusters
What objects did Harlow Shapley use as "signposts" to figure out the extent of the Milky Way Galaxy and the location of its center?
What kind of object is shown in the picture above?
globular cluster
The far right of the following graph illustrates ...
the high orbital velocities of stars near the outer parts of the galaxy due to dark matter
spiral
What kind of galaxy tends to have many young stars and an obvious disk component?
far away
All quasars have large redshifts. This implies that they are ...
incredibly hot
According to the Big Bang model, what was the temperature of the universe like at its inception?
it slows the expansion down
What tends to be the influence of matter on the expansion of the universe?