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a double-line spectroscopic binary system.
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
the distance traveled by a wave crest and the time taken.
To calculate the velocity of a wave, you need to know
resolving power.
To see small but bright objects such as the ice caps on Mars, you would need a telescope with large
The focal point
A converging lens will send light rays that are parallel to the axis through
a shallow bowl with the open part facing up.
A mirror that is supposed to bring light from a star directly overhead to a focus must be shaped like
10⁻⁴.
A star at a distance of 1000pc should have an apparent brightness equal to its absolute brightness multiplied by
100,000 parsecs.
A star is found to have absolute magnitude -1 and apparent magnitude 19. How far away is it?
0.4 seconds of arc.
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?
Of dazzling brightness
A star with an absolute magnitude of 8.4 and an apparent magnitude of -1.0 would appear in our sky as a star
100 times as bright.
Compared to a magnitude 6 star, a magnitude 1 star would be
Standard Candle
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
10 au
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?
only a minimum mass for each star.
For a spectroscopic binary star system, we can determine
the masses of both stars in the system.
For a visual binary star system, we can determine
the masses and diameters of both stars in the system.
For an eclipsing spectroscopic binary star system, we can determine
Distant objects are not behaving the same as nearby objects.
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?
4.8
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
12 m/s
Suppose that a sound wave has a wavelength of 12 meters and a frequency of 1Hz. What is the speed of sound?
moving toward us.
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
1000 parsecs.
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?
nearby stars to shift back and forth once a year.
The Earth's motion around the Sun causes
are lighter because they are thinner.
The main reason that telescope mirrors can be much larger than lenses is that the mirrors
can be corrected by using a guide star.
The problem of stars "twinkling" due to atmospheric turbulence
11 years.
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
1.9265′′/yr.
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
Waytoofar is closer to our Sun than Wemadeit.
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
3 parsecs.
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
400 nm and 424 nm
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
one region of maximum pressure.
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
sticking out the side near the front.
Think of the `front' of a telescope as the end that light enters. A telescope with Newtonian Focus has the eyepiece
Whichever is the lowest
Which of the following magnitudes corresponds to the brightest star?
5000.
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?
