Download Harpell/Astro 10

Harpell/Astro 10
Quiz 10
1. In essence, most of the extrasolar planets discovered to date have been
found by:
a) Closely examining very high-resolution photographs of other star systems.
b) Observing mini-eclipses of a star as an unseen planet passes in front of it.
c) Identifying spectral lines that look like what we expect to see from a planet rather than a star.
d) Observing a star carefully enough to notice that it is experiencing a gravitational tug caused by
an unseen planet.
2. Why is it so difficult to take pictures of extrasolar planets?
a) No telescope is powerful enough to detect the faint light from a distant planet.
b) Their light is overwhelmed by the light from their star.
c) Telescopes are too busy with other projects.
d) Extrasolar planets give off light at different wavelengths than planets in our solar system.
3. The astrometric technique looks for planets with careful measurements
of a star's _________.
a) brightness
b) velocity towards or away from us
c) position in the sky
d) all of the above
4. Suppose you are using the Doppler technique to look for planets around
another star. What must you do?
a) Compare many spectra of the star taken over a period of many months or years (or at least a
week).
b) Compare the brightness of the star over a period of many months or years.
c) Carefully examine a single spectrum of the star.
d) Compare many spectra of an orbiting planet taken over a period of many months or years.
e) Carefully examine a single spectrum of an orbiting planet.
5. In general, which type of planet would you expect to cause the largest
Doppler shift in the spectrum of its star?
a) a low-mass planet that is far from its star
b) a low-mass planet that is close to its star
c) a massive planet that is close to its star
d) a massive planet that is far from its star
6. Suppose a planet is discovered by the Doppler technique and is then
discovered to have transits. In that case, we can determine all the
following about the planet except ______________.
a) its physical size (radius)
b) its precise mass
c) its density
d) its rotation period e) its orbital period
7. You observe a star very similar to our own Sun in size and mass. This
star moves very slightly back and forth in the sky once every 4 months,
and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting
planet?
a) You do not have enough information to say anything at all about the planet.
b) The planet must be closer to the star than Earth is to the Sun.
c) The planet must be farther from the star than Neptune is from the Sun.
d) The planet must have a mass about the same as the mass of Jupiter.
8. All the following statements about known extrasolar planets are true.
Which one came as a surprise to scientists who expected other solar
systems to be like ours?
a) In some cases, we've found more than one planet orbiting the same star. Some of the planets orbit
their star more closely than Mercury orbits the Sun.
b) Most of the planets orbit stars that are quite nearby compared to the scale of the entire Milky Way
Galaxy.
c) Most of the planets are quite massive - much more like Jupiter than like Earth. (and closer to
their star then Earth is to the sun!)
9. Which of the following is /not/ expected for a "hot Jupiter" that orbits
0.05 AU from its star
a) cloudtop temperatures over 1000 K
b) clouds made of rock dust (weird but seems to be true)
c) density similar to or lower than Jupiter's
d) intense volcanism
10.
Based on everything you have learned about the formation of our solar
system, which of the following statements is probably /not/ true?
a) Planets always tend to orbit their star in the same direction and approximately the same plane.
b) Other planetary systems will have far more numerous asteroids and comets than actual planets.
c) Only a tiny percentage of stars are surrounded by spinning disks of gas during their formation.
d) Other solar systems will also have planets in the two basic categories of terrestrial and jovian.
(there seems to be a gray area beween them…)
11. To date, we've found very few planets orbiting their stars at distances
comparable to the distances of the jovian planets in our solar system.
Why do astronomers think this is the case?
a) No known technique can detect planets at such large distances.
b) Planets at such distances are probably very low in mass.
c) We have not yet been searching for planets at such distances for a long enough time.
d) Planets at such distances are extremely rare.
12. Current evidence suggests that many massive jovian planets orbit at very
close orbital distances to their stars. How do we think these planets
ended up on these close orbits?
a) These planets migrated inward after being born on orbits much farther from their stars.
b) These planets were captured from other solar systems.
c) These planets are jovian in nature and were able to form close to their stars because their solar
nebulas were very cold in temperature.
d) Despite their large masses, these planets are terrestrial in nature and therefore could form in their
inner solar systems.
13. Assuming that our ideas about how "hot Jupiters" ended up on their current orbits are correct, why
didn't our own solar system end up with
any hot Jupiters?
a) Our solar nebula must have stuck around for an unusually long time after the formation of jovian
planets.
b) The existence of Earth and the other terrestrial planets prevented the jovian planets from migrating
inward.
c) Our solar nebula must have been blown into space shortly after the formation of the jovian
planets.
d) Our jovian planets must have migrated outward from inside the orbit of Mercury.
14.
When is the soonest we are likely to have images and spectra of
Earthlike planets around other stars?
a) In just a few years, through the Kepler mission.
b) We already have images and spectra of Earthlike planets around other stars (we don’t really
have images, and it depends on what you call Earthlike—no place like home!)
c) Any day now, thanks to new, large, ground-based telescopes.
d) In a decade or two, through space missions now in the early planning stages.
15.
a)
b)
c)
d)
16.
What Do astronomers conclude from the graph below?
that there is one Jovian planet in an orbit similar to that of the Earth
that there are two or more planets in orbits ranging from about six months to 3 years.
There are three or more planets with orbits ranging from 4 days to 50 years.
That an Earth like planet is transiting its parent star three times per year.
According to the chart below, we should look for life bearing planets:
a) 10 AU from type m (red) stars
b) 5 AU from type G (yesllow) stars
c) .6 AU from type K (orange) stars
d) all of the above.