ASTR123 Modules 7-8

Which of the following is not a candidate for the identity of dark matter; a. primordial black holes b. weakly interacting elementary particles c. anti-matter d. MACHOs

c. anti-matter

Protons and neutrons are composed of other more elementary particles known as a. neutrinos b. anti-protons and anti-neutrons c. electrons d. quarks e. Higgs bosons

d. quarks

Roughly what percent of the mass and energy contents of the universe is made up of ordinary (atomic) matter? a. 5 percent b. 10 percent c. 50 percent d. 95 percent e. astronomers have no way of estimating this percentage

a. 5 percent

The three observational pillars of cosmology are the expanding universe, big bang nucleosyntheses, and a. the cosmic microwave background b. the age of globular cluster stars c. the rate of Type II supernovae d. the number of primordial black holes e. x-ray emission from black hole accretion disks

a. the cosmic microwave background

Why did Einstein introduce the cosmological constant into the equations of his General Theory of Relativity when describing the universe? a. Einstein did not realize that black holes would exist at the centers of galaxies and pull everything into them b. Einstein's equations required the universe to expand or contract; he could not imagine or accept it doing either one, so he put a factor in to stop it from moving c. Einstein talked to Hubble and learned about Hubble's observations of the expanding universe, which made him so uncomfortable that he decided to change his equations d. Einstein had a hunch that the universe was accelerating (speeding up its expansion) back in 1918 and so introduced the constant into his equations to describe that

b. Einstein's equations required the universe to expand or contract; he could not imagine or accept it doing either one, so he put a factor in to stop it from moving

If the universe consisted only of matter and its density were equal to critical, the universe would a. continue expanding, then slow down and contract, ending in a "big crunch b. continue expanding, eventually slowing down to zero c. continue expanding, eventually speeding up d. continue expanding at a reduced rate e. not expand at all

b. continue expanding, eventually slowing down to zero

When the age of the universe was about 10 seconds, it had cooled sufficiently for neutrons and protons to bind together and form the key nuclear species which allows production of helium to proceed. This key nucleus is called a. hydrogen b. deuterium c. lithium d. a quark e. carbon-6

b. deuterium

Based on the cosmic microwave background (CMB) data, astronomers now conclude that the average density of the universe is a. less than the critical density b. exactly equal to the critical density c. more than the critical density d. essentially equal to zero e. so great that the universe will experience a "Big Crunch" before the Sun becomes a red giant

b. exactly equal to the critical density

Galaxies that we see as they were 11 billion years ago or more, as compared to galaxies today, are generally: a. bluer and smaller b. redder and smaller c. redder and larger d. bluer and larger e. pretty much the same

b. redder and smaller

Recent observations indicate that the universe is expanding faster today than it was a few billion years ago (that, in other words, the expansion of the universe is accelerating.) What kind of observations have led astronomers to this surprising conclusion? a. the measurements of cepheid variables in the galaxies of the Local Group b. the measurement of galaxy distances using Type Ia supernovae c. the discovery of large amounts of dark matter in the halo of the Milky Way d. the measurements of the amount of deuterium in the universe

b. the measurement of galaxy distances using Type Ia supernovae

In the observation of galaxies, astronomers refer to look-back time, which means a. the glory days of astronomy b. the time it took for the observed light form a galaxy to reach us c. the current distance to a galaxy divided by c d. the time required to take a good spectral image of the galay e. Thursdays

b. the time it took for the observed light from a galaxy to reach us

The reason nucleosynthesis stopped when the age of the universe was about 3 minutes was a. because all the elements had been created at that point b. the universe was cooling too fast to produce elements beyond helium c. the universe was cooling too fast to produce elements beyond carbon d. the universe began re-heating, breaking apart any new nuclei e. it didn't stop, but began accelerating

b. the universe was cooling too fast to produce elements beyond helium

The observed cosmic microwave background (CMB) is extremely uniform. What is the significance of the small deviations from uniformity which show up as red or blue regions in the CMB images? a. they are known experimental errors b. they seed the large scale structure we observe today c. they turn into supermassive black holes d. they became the Virgo cluster of galaxies

b. they seed the large scale structure we observe today

Which of the following statements about dark matter is FALSE: a. it is observed to be a major part of the Milky Way b. it is observed to be present in other groups of galaxies c. astronomers have a pretty good idea of what the dark matter is made of d. we can detect its gravity, even though we can't see it e. it may make up even more of the universe that the mater we can see

c. astronomers have a pretty good idea of what the dark matter is made of

According to the Cosmological Principle, the universe a. has no beginning and no end b. cannot be understood by the use of scientific observations alone c. is isotropic and homogeneous over large d. consists only of galaxies that are exactly like the Milky way e. has all the galaxies arranged in groups about the size of our Local Group

c. is isotropic and homogeneous over large distances

The "horizon problem" is illustrated by what observation of the cosmic microwave background (CMB)? a. that the microwaves should not have been able to reach us b. that the size of the universe represented by the CMB seems to extend beyond the visible horizon c. that the temperature of disconnected regions is almost exactly the same d. that large scale structure doesn't seem to be implied from the CMB e. that the CMB is analogous to a black hole horizon

c. that the temperature of disconnected regions is almost exactly the same

How do astronomers currently think the amount of detectable (observable) matter in the universe compares to the amount of dark matter? a. the amount of detectable matter is about equal to the amount of dark matter b. the amount of detectable matter is far greater than the amount of dark mater c. the amount of detectable matter is about 1/5th the amount of dark matter d. the amount of detectable matter is about 1% the amount of dark matter

c. the amount of detectable matter is about 1/5th the amount of dark matter

An astronomer is observing a distant galaxy at loopback time of 11 BY which looks blue. Which of the following can she conclude from this observation? a. the galaxy must be moving toward us (must have a blue shift) b. the galaxy must be extremely large (probably a giant elliptical) c. the galaxy must have a lot of star formation going on at the same time we are seeing it d. the galaxy must be rotating very slowly or not at all e. the galaxy must contain only older stars (those that formed billions of years ago)

c. the galaxy must have a lot of star formation going on at the same time we are seeing it

With enormous effort, a team of astronomers manages to collect enough light from a galaxy, far, far away [*] to produce a spectrum. That spectrum has lines from the elements carbon, silicon, and sulfur. This tells the team that a. the galaxy must be closer to us that 1 billion years b. the galaxy must contain a quasar c. the galaxy must have had an entire generation of stars that was born, lived, and died d. the galaxy must be a massive elliptical galaxy *footnote: 'far, far away' is a bit vague. I would replace with 'with loopback time 11 billion years' for example.

c. the galaxy must have had an entire generation of stars that was born, lived, and died

Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is a. 4.6 billion years b. about 100 billion years c. roughly 2 million years d. about 13.8 billion years e. the age of the universe is infinite; there was no beginning

d. about 13.8 billion years

Where in space did the expansion of the universe begin? a. at the center of the Milky Way Galaxy; that's why all the other galaxies are moving away from us b. near the center of the Virgo Supercluster of Galaxies c. at a point so far away that only our largest telescopes can show us glimpses of it d. everywhere at once e. nowhere at all; new observations show that the universe is not expanding after all

d. everywhere at once

Measurements of the cosmic microwave background provide strong evidence that the overall geometry of space is a. trapezoidal b. spherical, or positive curvature c. hyperbolic, or negative curvature d. flat, or zero curvature e. circular

d. flat, or zero curvature

Which of the following does NOT happen when two galaxies collide? a. large interstellar gas clouds collide b. the rate of star formation increases c. the shape of the galaxy is often changed d. many of the stars in one galaxy collide with the stars in the other e. a smaller galaxy may wind up inside a larger one

d. many of the stars in one galaxy collide with the stars in the other

Which of the following did NOT happen during the first few minutes after the Big Bang? a. temperatures throughout the universe were hotter than the cores of stars are today b. two or three of the simplest elements fused together c. energy was converted to matter d. some very massive early stars formed e. matter and antimatter collided and turned into energy

d. some very massive early stars formed

The model of the universe that involves an enormous increase of size during a very short time in the early universe is called: a. the flat universe model b. the oscillating universe model c. the primeval atom model d. the inflationary universe model e. the cosmic burp model

d. the inflationary universe model

Which of the following does not represent evidence for dark matter? a. the rotation curves of stars moving around galaxies b. the large scale structure of galaxies and galaxy clusters c. analyzing the mass of gravitational lenses d. the rate of cosmic ray showers e. merging galaxy clusters such as the "bullet cluster"

d. the rate of cosmic ray showers

What happened when the age of the universe was 380,000 years which allows us to observe the cosmic microwave background? a. ancient civilizations developed microwave ovens b. the formation of the first stars c. the formation of the first galaxies d. the universe cooled sufficiently to allow neutral hydrogen to form e. the universe cooled sufficiently to allow deuterium to form

d. the universe cooled sufficiently to allow neutral hydrogen to form