Astronomy Final
From which location could you observe all of the stars during the course of a year?
Equator
When we look at a star through dust in the interstellar medium, it looks
Fainter AND redder
True or False: Astronomers now believe that all galaxies start out as irregulars, evolve in their youth into ellipticals, and then become spirals as they mature and reach old age.
False
True or False: Distance and ages to stars are easier to measure than their temperatures.
False
True or False: Every lunar cycle, we get a solar and lunar eclipse.
False
True or False: Most planets in our solar system have similar properties to the Earth
False
True or False: Retrograde motion is when planets move backwards in their orbits for a short period of time.
False
True or False: Stars rise in the West and set in the East.
False
True or False: The apparent and absolute magnitude of a star can never be the same.
False
True or False: We don't have techniques to characterize atmospheres around other exoplanets yet.
False
True or False: We've found the most exoplanets using the astrometric detection technique.
False
We use parallax to find the distances to the distant galaxies in the universe.
False
One difference between open clusters and globular clusters is
Globular clusters only have red stars
Stars move from phase to phase in their evolution as a consequence of
Gravity beating pressure as fuel in their cores runs out
Why don't we use the direct imaging method for more planets
most stars are too far away
How long does it take the Moon to orbit the Earth once?
1 month
If a planet always has the same distance to the Sun throughout its whole orbit, its orbital eccentricity is
0
How long does it take the Earth to orbit the Sun once?
24 hours
Which of these stars helps chemically enrich the ISM with iron?
Dan, a 9MSun B star
What's a problem with the disk instability theory of planet formation?
It doesn't explain how you form terrestrial planets
The North Star (Polaris) does not appear to move throughout the night because
It is positioned directly over the Earth's north pole
How would the orbital period of a planet change if I decreased the semi major axis of itsorbit? Which law tells us this?
It would get shorter, Kepler's 3rd law
What's a big difference between the life cycles of low-mass stars and high mass stars?
Low mass stars can't fuse carbon into anything, high stars can
Which of these describes the life cycle experienced by a low-mass star?
Main sequence, red giant, planetary nebula, white dwarf
What property of the star ultimately determines its lifespan and life cycle?
Mass
You look at four stars with different spectral types. Which one lives for the shortest amount of time?
O stars
What method is normally used to measure distances of stars in the Milky Way
Parallax
Why is there a four minute difference between a solar day and a sidereal day?
The Earth is moving in its orbit around the Sun
the Sun sets in the sky every 24 hours because
The Earth spins around on its axis once every 24 hours
There is a lunar eclipse when
The Moon passes through the Earth's shadow
1 AU is
The average distance between the Earth and the Sun
One strength of the Giant Impact Hypothesis for the Moon's origin is that it naturally explains
The difference in iron between the Moon and the Earth
Which statement below best explains why the James Webb Space Telescope was optimized for infrared viewing in order to study early galaxy formation in the universe?
The earliest galaxies are the most distant, and universal expansion has redshifted their spectra into infrared wavelengths.
A consequence of Earth's Precession is
There will be a new North star in the next few thousands of years
You take the spectral energy distribution (SED) of a star and observe a signal of infrared excess. What can you conclude about that star?
There's a disk of dust and gas around that star
Why do Type Ia supernovae make for good standard candles?
They are roughly always the same luminosity
Why do low mass stars live for so long?
They aren't very luminous
Over time, the ISM has gotten more chemically enriched relative to the early universe thanks to the death of stars.
True
True or False: Astronomers today think that dwarf elliptical galaxies may be the most common kind of galaxy in the universe.
True
True or False: Our class will see different constellations at night between today and six months from now.
True
True or False: Right ascension and declination is similar to latitude and longitude.
True
True or False: The Sun's corona is hotter than its surface, and we're still not entirely sure why.
True
True or False: The density of a planet tells us something about its composition.
True
True or False: White dwarfs are more common than neutron stars and black holes.
True
What's a problem with the transit method of finding exoplanets
We can only look at systems that are edge on
Why do astronomers like studying stellar clusters
We know those stars are about the same distance and age and composition
How does the transit method of discovering exoplanets work?
We measure how bright a star looks with time and see it get slightly fainter periodically
How do astronomers interpret the signal from pulsars
We're observing collimated radio emission coming from their rapidly spinning poles
Which type of radiation has the most energetic photons?
X-rays
Which of the following statements about the different types (shapes) of galaxies is correct? (a) collisions and mergers between galaxies can sometimes change a galaxy's type (shape) (b) 90% of all galaxies are spirals (including our Milky Way); the other two types are very unusual (c) all galaxies start out as ellipticals, but some later evolve to be spirals and irregulars (d) whatever type a galaxy is at its birth, that's what it will be for all time (e) what type we see a galaxy to be just depends on the angle at which we happen to see it; all galaxies look roughly the same in shape
a
What happens in a type Ia supernova?
a white dwarf explodes as a consequence of funneling mass from its companion
If you take a spectrum of the Sun, you get:
an absorption spectrum
The disks of spiral galaxies have a blue hue because they
are still undergoing star formation
Where do stars always circle the zenith (and never rise and set)?
at the North Pole
what seems to have played a role in water being on Mercury and the Moon
comets and asteroids
Which of the following is NOT a characteristic of a spiral galaxy? (a) it has quite a bit of gas and dust in it (b) the bright stars in it can be seen organized into distinct spiral arms (c) most of its material is in the shape of a flattened disk (d) when we take spectra of its stars, they have far less of the heavier elements than the Sun (e) it has young stars and bright emission nebulae
d
Which of these are NOT true about protostars? (a) Protostars are still gaining mass in a process called accretion (b) Protostars have powerful jets shooting from their poles (c) Protostars have disks of dust and gas surrounding them (d) We try to observe protostars in the visible versus the infrared (e) All of these are true
d
General relativity tells us that: (a) Mass causes distortions in spacetime (b) Gravity can operate differently than what Newtonian physics predicts (c) Time moves slower near objects with a lot of mass (d) Black holes should emit gravitational waves, which we can detect (e) All of these
e
What are some problems w/ the standard candle approach of estimating astrophysical distances? (a) Errors between the methods accumulate with each new method (b) We aren't able to get distances outside of the galaxy with this approach (c) We aren't sure if standard candles are really universally standard objects (d) Pulsating giant stars don't make for good standard candles (e) A and C
e
What factors can affect the habitability zone of an exoplanet? (a) The host star and other planets (b) The presence of an atmosphere on the exoplanet (c) The tilt of the exoplanet (d) Tides (e) All of these
e
if you see a red star in the sky, you can conclude (a) It must be old (b) It is going to live for a long time (c) It isn't a very massive star (d) All of these (e) We need more information before concluding any of the above
e
Which type of galaxy is observed to contain mostly older stars?
elliptical
The Sun is powered by
fusion in its core
As you go out from the center of the Sun to its outermost regions the temperature
gets colder then hotter again
The Milky Way
has a supermassive black hole in its center
What can we learn about from conducting spectroscopy?
how hot something is, how quickly it's moving towards or away from us, what elements a gas cloud is made of, and the orbital period of a star
When stars are on the main sequence, they fuse what element in their cores?
hydrogen into helium
To make the gravitational attraction weaker between two objects, I could
increase the distance between them
What do the flat rotation curves of the Milky Way tell us?
it argues for the existence of dark matter
The Earth's atmosphere is protected from the Solar wind because
of the Earth's magnetic field
Our observations of "Hot" jupiters is evidence in support of
planet migration
Which type of radiation has the longest wavelength
radio waves
The type of galaxy that sometimes has a distinct bar of stars running across the central region is
spiral
In which type of galaxy are you likely to observe a significant amount of star formation?
spiral and irregular
How do astronomers currently think the amount of detectable (observable) matter in the universe compares to the amount of dark matter and dark energy?
the amount of detectable matter is far less than the amount of dark matter & energy
How bright a star looks in the sky depends on what?
the distance and the luminosity of the star
Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the
the fast it is moving away from us
Of the following types of radiation, which travels the fastest?
they all travel at the same speed
Circumpolar stars have this special quality:
they never rise or set