Astronomy Final 2
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Astronomy Final 2
The diagram below illustrates a light source, a gas cloud, and three different lines of sight. Along which line of sight would an observer see an absorption spectrum?
An atom can be excited
b. if it collides with another atom or electron.
c. if it absorbs a photon.
a. are cooler than their surroundings.
Granulation is caused by
b. rising gas below the photosphere
The chromosphere of the sun
a. is hotter than the photosphere.
The centers of granules
a. are hot material rising to the photosphere from below.
We know that giant stars are larger in diameter than the sun because
a. they are more luminous but have about the same temperature.
A recent sunspot maximum occurred in 2001, what is the year of the sunspot maximum that immediately follows the 2001 maximum if the solar cycle continues?
Which of the following types of electromagnetic radiation has the greatest energy?
Which of the following types of electromagnetic radiation has the lowest energy?
e. infrared radiation
When we say that gravitation is universal we mean that
e. it is a property of all matter.
The force due to gravity between two objects depends on
I. the mass of each object.
III. the distance between the two objects.
Radio telescopes have poor resolving power because
c. radio waves have long wavelengths.
The __________ of an object is a measure of the amount of matter it contains. On the other hand __________ is a measure of the gravitational force on an object.
b. mass weight
a. has a greater energy than red light.
The Copernican system was no more accurate than the Ptolemaic system in predicting the positions of the planets because
c. the Copernican system included uniform circular motion.
Which of the following types of electromagnetic radiation has the highest frequency?
Galileo's telescopic discoveries of mountains on the moon and spots on the sun were controversial because they suggested that the sun and moon
b. were not perfect spheres
A(n) __________ is a circle whose center is located on the circumference of another circle.
Which of the following types of electromagnetic radiation has the smallest frequency?
A telescope that suffers from chromatic aberration and has a low light gathering power is most likely
b. a small diameter refracting telescope.
Astronomers build telescopes on tops of mountains because
a. there is less air to dim the light.
b. the seeing is better.
Galileo's observations of the gibbous phase of Venus proved
a. that Venus orbited the sun.
Newton concluded that some force had to act on the moon because
c. a force is needed to pull the moon away from straight-line motion.
__________ has (have) wavelengths that are longer than visible light.
c. Infrared radiation
The __________ of a telescope is a measure of its ability to show fine detail and depends on the diameter of the objective.
d. resolving power
Complete the following diagram clearly showing the following:
The star groupings.
The percentage of stars on each of these groupings.
The name of each of these groupings
Name the layers of our sun starting with the first visible layer and work outward.
Refracting telescopes suffer from __________ aberration.
The first observations of objects in the solar system that orbited neither the sun nor Earth were made by __________.
Uranus' orbital period is 84 years, how far is Uranus from the sun? _____________
Fill in the following table:
: O, B, A. F, G, K, M
: 40,000, 20,000, 10,000, 7,500, 5,500, 4,500, 3,000
: weak, medium, strong, medium, weak, very weak, very weak
: ionized helium, neutral helium, ionized calcium, ionized calcium, ionized calcium, ionized calcium, titanium oxide
Why would parallaxes be easier to observe if Earth were farther from the sun?
What are the current methods used to determine distance?
What evidence do we have that the sunspots are magnetic?
What advantages does a large diameter astronomical telescope have over a telescope of a smaller diameter?
Better light gathering power
Better resolving power
What are Kepler's three laws?
planets move in ellipses with the sun at one foci
planets vectors sweep equal area in equal time
P2 = D3
Describe the differences between the Ptolemaic, Tychonian and Copernican models of the universe.
Ptolemy - geocentric
Tycho - geocentric and heliocentric (the sun revolved about the earth and the other planets revolve about the sun)
Copernicus - heliocentric
How do atmospheric windows limit observations made from Earth's surface?
Only electromagnetic radiation from the Visual and Radio Windows are allowed to penetrate through the Earth's atmosphere.
If Copernicus overthrew the geocentric universe, what did Kepler overthrow?
uniform circular motion
What are Newton's three laws of motion.
an object at rest/motion will stay so unless acted upon by another force
for every action there is an opposite and equal reaction
Why does it not occur in reflecting telescopes?
Chromatic abberations are caused by the bending of light passing through a lens, Reflecting telescopes use a mirror as the primary lens to avoid this problem.
Spiral tracers tend to be old, luminous stars.
The density wave theory explains spurs and branches along the spiral arms.
The disk of the galaxy is older than the halo.
The rapid rotation in the outer disk suggests that our galaxy is more massive than previously thought.
The center of our galaxy shows signs of past eruptions.
Shapley found the distance to the center of the galaxy by studying the distance to open clusters.
Neutron stars have densities roughly the same as that of the atomic nucleus.
Theory predicts that neutron stars may not exceed 3 solar masses.
Pulsars could not be pulsating stars because the pulses are too short.
Many pulsars have periods that are gradually increasing as the spinning neutron stars lose energy.
The event horizon marks the boundary within which the density is roughly the same as that of the atomic nucleus.
We expect neutron stars to spin rapidly because they conserve angular momentum.
If the accretion disk around a black hole emits X rays outside the event horizon, the X rays can escape.
When two galaxies collide, they pass through each other and their stars almost never collide.
Cepheid variable stars are more luminous than the sun.
When a large galaxy collides with a small galaxy, the smaller galaxy may be pulled apart by tidal forces.
Elliptical galaxies contain more gas, dust and young stars than do Sa galaxies.
Some large clusters of galaxies do not appear to contain enough mass to hold themselves together.
Double-lobed radio galaxies appear to be emitting jets of gas and radiation.
The rapid fluctuations of quasars show that the objects must be very small.
The look-back time is numerically equal to the distance to a galaxy in light-years.
Some quasars have fuzz around them that produces spectra similar to normal galaxies.
Until recently, most astronomers thought elliptical galaxies were shaped like oblate spheroids.
The rotation curve method can be applied only to pairs of galaxies orbiting each other.
The Milky Way galaxy is not a radio galaxy, it emits no radio radiation.
Quasar red shifts are usually larger than the red shifts of the visible galaxies.
Stars swell into giants when hydrogen is exhausted in their centers.
Helium fusion does not begin until the star has entered the giant region of the H-R diagram.
The sun makes most of its energy by the CNO cycle.
The thermal motions of the atoms in a gas cloud can make it collapse to form a protostar.
No known white dwarf has a mass greater than the Chandrasekhar limit.
The helium flash is the cause of some supernovae.
Even in degenerate matter, pressure depends on temperature.
Because more massive stars have more gravitational energy, they can fuse heavier nuclear fuels.
Hydrostatic equilibrium refers to the balance between weight and pressure.
A nova destroys the star and leaves behind a white dwarf.
Type II supernovae are believed to occur when the cores of a massive stars collapse.
A Type II supernova produces a planetary nebula.
The dust in the interstellar medium can make distant stars look redder than they really are.
The sun has a core in which energy travels outward primarily by radiation.
Giant and supergiant stars are rare because that stage of stellar evolution is short.
Stars less massive than 0.4 solar mass never become giant stars.
Once a star ejects a planetary nebula, it becomes a white dwarf.
Ninety percent of all stars fuse helium to form carbon and lie on the main sequence.
Young star clusters have bluer turn-off points than old clusters.
Planetary nebulae are sites of planet formation.
The sun will eventually become a supernova.
The center of our galaxy lies in the direction of the constellation of
Which of the following is not a characteristic of the stars of the disk component of our galaxy?
b.randomly inclined orbits
Radio maps of the spiral arms of our galaxy
e.map the location of dense neutral hydrogen clouds.
The nuclear bulge of our galaxy
c.contains stars primarily associated with the spherical component of our galaxy.
The orbits of population I stars
I.are confined to disk of the galaxy.
III.are nearly circular.
Good spiral tracers are all
The first stars to form in our galaxy
b.had highly elliptical orbits.
The chemical abundance of population I stars
b.indicates that the material they formed from had been enriched with material from supernovae.
Although neutron stars are very hot, they are not easy to locate because
e.they have small surface areas.
An isolated black hole in space would be difficult to detect because
d.very little matter would be falling into it.
The event horizon
c. has a radius equal to the Schwarzschild radius.
None of the pulsars emit pulses of visible light because
e. A few pulsars do emit visible light pulses.
The density of a _________ is greater than the density of a _________.
d. pulsar white dwarf
The search for black holes involves searching for
b. x-ray binaries where the compact companion has a mass in excess of 3 M.
As material flows into a black hole
a. the material will experience time dilation.
b. the material will become hotter.
The first pulsar was discovered by _________ in November of 1967.
a. Jocelyn Bell
The density of a neutron star is
c. about the same as an atomic nucleus.