TEST2 AST1000 STUDY GUIDE
Chapter 7
In brightness (as seen from Earth), Jupiter is second only to the planet Venus most of
the time.
In the telescope, Jupiter shows the most turbulent atmosphere with changes easily
seen even with amateur telescopes.
The most famous and long lasting storm in the solar system is Jupiter's Red spot spot.
Jupiter is largest and brightest in our skies when seen at Opposition with respect to the
Sun and the Earth
Adams and Leverrier predicted the position of Neptune, which Galle confirmed.
William Herschel discovered the green disk of Uranus as the first telescopic planet.
While Saturn is almost as large as Jupiter, its mass is only about About 1/3that of
Jupiter's.
The oblateness of the jovian disks is caused by their rapid Rotations.
Compared to the terrestrial planets, the Jovians have Smaller average densities.
Of the planets, Saturn is the least dense, and could float on water.
Like Jupiter's, Saturn's rotation is fast and differential, with the Equator rotating
fastest.
Compared with Jupiter and Saturn, Uranus and Neptune have very strange magnetic
field pole directions with respect to their rotation axes.
In general, the wind directions Reverse between adjacent bands in Jupiter's
atmosphere.
Jupiter's bright zones are cloud streams made of Ammonia ice crystals.
Jupiter's darker Bands are complex in color and origin, with complex organic
molecules including carbon, sulfur, and nitrogen.
The Great Dark Spot of Neptune was striking in 1989, but gone by 1995.
Uranus and Neptune are very similar in size, mass, and color.
The most abundant element in Saturn's atmosphere is Hydrogen.
Because it has a higher percentage of Methane, Neptune appears even bluer than
Uranus.
Compared to Jupiter, the element helium is notably less common in Saturn's
atmosphere, perhaps condensing to fall core-ward as rain.
The outer cores of Jupiter and Saturn are made of liquid Hydrogen.
While the rotation axis of Neptune is only tilted 29 degrees, its magnetic field is just
as strange as its twin's is.
Their magnetic fields should originate in the planets' Core, but those of Uranus and
Neptune don't even come close.
Jupiter's magnetic field is produced in its rapidly spinning mantle of liquid Metallic
hydrogen (two words).
Chapter 7 (quiz)
The most abundant element in the sun (at the moment) is hydrogen. True
The density in the solar corona is much higher than in the photosphere. False
Sunspots appear dark because they are much hotter than the surrounding gas in the
photosphere. False
The proton-proton chain reaction releases energy because mass is created in the
process. False
The sun spins on its axis roughly about once a month
Chapter 8
What is thought to cause Io's volcanism? tidal stresses from both Jupiter and Europa
The surface of Europa is most like the earth's Arctic ocean
The weak magnetic fields around Europa and Ganymede were found during flybys of
Galileo
Of the Jovian satellites, which shows the oldest, most cratered surface Callisto
Which of these moons has the densest atmosphere? Titan
For a moon the same density as its planet, the Roche limit lies at approximately 2.5
times the radius of its planet.
The Cassini Division is a gap in Saturn's rings caused by gravitational interaction with
Mimas
What is the meaning of the solar constant? the amount of energy the earth receives per
unit area and unit time
The Sun's average density is almost exactly the same as Jupiter
What two energy transport mechanisms, in order from outside the core to the surface,
is found in the Sun? radiative diffusion, convection
The solar winds blow outward from coronal holes
A loop of gas following the magnetic field lines between sunspots' poles is a
prominence
As the Sun rotates, an individual sunspot can be tracked across its face. From eastern
to western limb, this takes about two weeks
A maximum in solar activity should next occur about 2012
What natural barrier must be overcome for two protons to collide and fuse together?
electrostatic repulsion
In the proton-proton cycle, the helium atom and neutrino have less mass than the
original hydrogen. What happens to the lost mass? it is converted to energy (E = mc2)
(E equals the velocity of light times the mass squared.)
The solution to the solar neutrino problem which won a Nobel Prize in 2002 was 2/3
of the neutrinos decay into a new form in the 8 minutes to Earth
If 2.00 kg of mass is converted to energy, how much energy will be produced? 1.80
1017 J
Chapter 8 (quiz)
If a star has a parallax of 1 arcsecond, how far away is it? 2500parsecs
The closest star to the sun is Proxima Centauri
An O and M star are very hot and much colder respectively
Star clusters are good for studying stellar evolution
The turn off point on the main sequence of a H-R diagram tells us the average age of a
star cluster
Chapter 9
A star has a parallax of .05 arc seconds, its distance is 20 parsecs
If spectroscopic luminosity classification gives us an estimated distance to the faint
star SAO 47552 of about 3300 light years, then its parallax would be only 0.001
arcseconds
The stars Cygni and cygni are in the constellation Cygnus. Which statement can
we claim is true? cygni appears brighter
Two stars both have parallaxes of 0.023 arseconds, but star A has apparent magnitude
2.3, while star B is magnitude 7.3. Which statement is true? Star A is both 100 times
brighter and more luminous than star B
The spectral type of a star is primarily a measure of its Temperature
Which of these stars would be the hottest? B0
What be can said with certainty about a red star and a blue star The blue star is hotter
than the red star.
Which of these pairs of binaries would appear most similar in color telescopically?
M1V and K9V
In general, what can be said about type O and B stars compared to type K and M stars
They are hotter and younger
The stars with masses comparable to our Sun's, but sizes like the earth are white
dwarfs
In the H-R diagram, what are the two most important (common) types of data plotted
spectral classes (and/or temperature) and absolute magnitude (and/or luminosity)
On the H-R diagram, our Sun lies about the middle
On the H-R diagram, red supergiants like Betelguese lie at the top right
Compared to the size of the Sun, stars of all types range from approximately 0.01 to
1,000 solar radii
Binary stars separated enough to be resolved in a telescope are called visual binaries
If we know the average separation and period of revolution for a binary system, we
can then determine the total mass of the system
What information can be gained from the light curves of eclipsing binaries their
relative sizes and period of orbit
Interstellar gas is composed mainly of 90% hydrogen, 9% helium
Which statement about the dark nebulae is true? They can be penetrated only with
longer wavelengths such as radio and infrared
Due to absorption of shorter wavelengths by interstellar dust clouds, distant stars
behind the clouds appear redder
Emission nebulae like M42 occur only near stars that emit large amounts of ultraviolet
radiation
What is the primary visible color of an emission nebula? red due to ionized hydrogen
atoms
What two things are needed to create an emission nebulae hot stars and interstellar
gas, particularly hydrogen
What information does 21 cm radiation provide about the gas clouds? Hydropgen
The average temperature of the typical dark dust cloud is about 100 K
When an electron in H changes its spin from the same to the opposite direction as the
proton, it a radio wave photon
On a H-R diagram, a protostar would be above and to the right of the main sequence
The single most important determinant of the temperature, density, radius, luminosity,
and pace of evolution of a protostar is its mass
How long does it take an M class star to reach the main sequence, compared to a solar
type star about twenty times longer
Which is characteristic of globular star clusters? old age and hundreds of thousands of
stars, only about 30 ly wide
Chapter 10
Compared to a cluster containing type O and B stars, a cluster with only type F and
cooler stars will be older
In a fairly young star cluster, if the most massive stars are swelling up into giants, the
least massive stars are continuing to shine as stable main sequence stars
Noting the turnoff mass in a star cluster allows you to determine its age
Which is used observationally to determine the age of a star cluster the luminosity of
the main sequence turn off point
What is the typical age for a globular cluster associated with our Milky Way? 10 to 12
billion years
The brightest stars in a young open cluster will be massive blue stars at the top left on
the HR diagram
A recurrent nova could eventually build up to a type I supernova
What can you conclude about a Type I supernova? It was originally a low mass star
Which of these does not depend on a close binary system to occur? a type II
supernova
The Chandrasekhar Limit is the upper mass limit for a white dwarf
Type II supernovae occur when their cores start making iron
The heaviest nuclei of all are formed in the core collapse that sets the stage for a type
II supernovae
Which of the following best describes the evolutionary track of the most massive stars
on a H-R diagram? horizontal right
As a 4 to 10 solar mass star leaves the main sequence on its way to becoming a red
supergiant, its luminosity remains roughly constant
A 20 solar mass star will stay on the main sequence for 10 million years, yet its iron
core can exist for only a day
In a neutron star, the core is made of compressed neutrons in contact with each other
Important properties of young neutron stars are extremely rapid rotation and a strong
magnetic field
An object more massive than the Sun, but roughly the size of a city, is a neutron star
The mass range for neutron stars is 1.4 to 3 solar masses
Most pulsars are observed only as radio sources
Who discovered the first four pulsars Jocelyn Bell
Many of the millisecond pulsars lie in globular clusters
X-ray bursters occur in binary systems, containing a red giant and a neutron star
A proposed explanation for gammaray bursters is red giant and a neutron star
In a hypernova, a very energetic supernova creates a black hole
The densely packed neutrons of a neutron star cannot balance the inward pull of
gravity if the total mass is greater than Schwartzschild's limit of 3 solar masses
What explanation does general relativity provide for gravity? Gravity is the result of
curved spacetime
As a spaceship's velocity gets closer to the speed of light its length will decrease and
its clock will run more slowly
As a spaceship nears an event horizon, a clock on the spaceship will be observed to
run slowly
If light from a distant star passes close to a massive body, the light beam will bend
towards the star due to gravity
What is Cygnus X-1? the leading candidate for an observable black hole binary
system
The largest known black holes lie in the centers of the most massive galaxies
A method for identifying a black hole is to look for their effects on nearby
companions