tophat questions for exam 4
The star Wemadeit shows a stellar parallax angle of 0.3 seconds of arc while the star Waytoofar shows a stellar parallax angle of 0.4 seconds of arc. From this, you can conclude that
Waytoofar is closer to our Sun than Wemadeit
The Earth's motion around the Sun causes
all stars to jump randomly around
The main reason that telescope mirrors can be much larger than lenses is that the mirrors
are lighter because they are thinner
The problem of stars "twinkling" due to atmospheric turbulence
can be corrected by using a guide star
13.5-2 A star with an absolute magnitude of 8.4 and an apparent magnitude of -1.0 would appear in our sky as a star
of dazzling brightness
13.4-3 Which of the following magnitudes corresponds to the brightest star?
-4.2
A star is seen to move by 0.8 seconds of arc between March 1, 1999 and September 1, 1999 and then back to its starting point on March 1, 2000. What is the parallax angle for this star?
0.4 seconds of arc
The star Tau Ceti has moved across the sky by 1922 seconds of arc during the last thousand years, more than a half of a degree of arc. Its proper motion is closest to
1.9265′′/yr
Cruising far from the Sun, we notice that the Sun's apparent brightness has dimmed to 10 watts per square meter. We know that the apparent brightness at a distance of 1au is 1000 watts per square meter. How far from the Sun are we?
10 au
13.4-4 Compared to a magnitude 6 star, a magnitude 1 star would be
100 times as bright
13.5-4 A star is found to have absolute magnitude -1 and apparent magnitude 19. How far away is it?
100,000 parsecs
13.5-3 Suppose that the color and behavior of a star identify it as a type that we know has absolute magnitude --3. If the star's apparent magnitude is found to be 7, how far away is it?
1000 parsecs
13.4-2 A star at a distance of 1000pc should have an apparent brightness equal to its absolute brightness multiplied by
10⁻⁴
The star 61-Cygni is 3.3 parsecs from our Sun. The light from this star in the "serpent holder" constellation has been traveling for approximately
11 years
Suppose that a sound wave has a wavelength of 12 meters and a frequency of 1Hz. What is the speed of sound?
12 m/s
The star epsilon-Eridani shows a heliocentric stellar parallax near 1/3 seconds of arc. The distance from our Sun to epsilon-Eridani is near
3 parsecs
13.5-1 Our own Sun has an absolute visual magnitude of 4.8. A starship that travels 10 parsecs from our Sun and looks back at the Sun will see it as having apparent visual magnitude
4.8
The violet lines in the Hydrogen spectrum are normally seen with wavelengths 410 nm and 434 nm. In the light of a star that is moving toward us, we might expect to see those lines at wavelengths of
400 nm and 424 nm
You hear a 1000Hz tone from a radio that is 20 feet away from you and listen for 5 seconds. How many pressure maxima pass by your ear?
5,000
13.5-6 Of all the things that might go wrong with distances found by using the method that astronmers refer to as the "distance ladder," which of these is the one that an astronomer would say is most likely?
Distant objects are not behaving the same as nearby objects
14.1-2 Which of the following spectral classes corresponds to the second lowest surface temperature (on this list)?
G
14.1-4 Which of the following spectral types corresponds to the star with the lowest surface temperature?
G5
14.1-3 Which of the following spectral types would you expect to look red in color?
M
We see what appears to be a single star. However, when the light from the star is put through a spectrometer, we see two distinct spectra, shifting back and forth. The star is actually
a double-line spectroscopic binary system
A mirror that is supposed to bring light from a star directly overhead to a focus must be shaped like
a shallow bowl with the open part facing up
Suppose that a star has a spectrum that includes red, blue, and violet lines spaced in the pattern of the lines from hydrogen but the red line is has a wavelength of 650 nm instead of the usual 656 nm. From this evidence, you can conclude that the star is
moving toward us
The wavelength of the sound waves that correspond to middle-C is about 4 feet. If you are standing 4 feet away from a piano that is playing that note, then between you and the piano there will usually be
one region of maximum pressure
For a spectroscopic binary star system, we can determine
only a minimum mass for each star
14.1-1 A star that is cooler than most other stars will probably look
red
To see small but bright objects such as the ice caps on Mars, you would need a telescope with large
resolving power
13.5-5 Consider a light source whose absolute magnitude can be deduced from the properties of the light that reaches us from that source. Astronomers often refer to this sort of object as a
standard candle
Think of the `front' of a telescope as the end that light enters. A telescope with Newtonian Focus has the eyepiece
sticking out the side near the front
To calculate the velocity of a wave, you need to know
the distance traveled by a wave crest and the time taken
A converging lens will send light rays that are parallel to the axis through
the focal point of the lens
For an eclipsing spectroscopic binary star system, we can determine
the masses and diameters of both stars in the system
For a visual binary star system, we can determine
the masses of both stars in the system
