Astronomy Test 2 (chapter 12,
What is the upper limit to the mass of a white dwarf?
1.4 solar masses
How many helium nuclei fuse together when making carbon?
3
come
A icy leftover planetesimal orbiting the Sun is
What characteristic distinguishes a meteorite from a terrestrial rock?
A meteorite usually has a high metal content, Meteorites contain rare elements, such as iridium, that terrestrial rocks do not, A meteorite is usually covered with a dark crust from burning in Earth's atmosphere, Meteorites have different isotope ratios of particular elements when compared to terrestrial rocks.
aestroid
A rocky leftover planetesimal orbiting the Sun is
can occur only in a binary system, and all such events are thought to have about the same luminosity.
A(n) white dwarf supernova
Why do asteroids and comets differ in composition?
Asteroids formed inside the frost line, while comets formed outside.
How can we determine the reflectivity of an asteroid?
By comparing its brightness in visible light to its brightness in infrared light.
most distant of the galielean moons: entire surface appears heavily crateres and ancient
Callisto
Which of the following best describes the internal layering of Jupiter, from the center outward?
Core of rock, metal, and hydrogen compounds; thick layer of metallic hydrogen; layer of liquid hydrogen; layer of gaseous hydrogen; and cloud layer.
When we see a meteor shower, it means that _________.
Earth is crossing the orbit of a comet
An icy object that orbits in the Kuiper belt and is more massive than Pluto
Eris
one of the galielean moons: covered in ice and some impact craters, riged surface suggest an ocean below
Europa
When a star exhausts its core fusion fuel so that the core begins to contract, which of the following can stop the contraction?
Fusion of another element. and Degeneracy pressure.
One of the galielean moons: largest moon in solar system heavily cratered terrain mixed with smooth
Ganymede
Why isn't there a planet where the asteroid belt is located?
Gravitational tugs from Jupiter prevented material from collecting together to form a planet.
It has the lowest mass per nuclear particle.
In what way is iron unique among the elements?
What is interstellar reddening?
Interstellar dust absorbs more blue light than red light, making stars appear redder than their true color.
All the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io?
Io orbits Jupiter on an elliptical orbit as a result of orbital resonances with other satellites.
What do we mean by the event horizon of a black hole?
It is the point beyond which neither light nor anything else can escape.
What is Pluto's moon Charon thought to have in common with our own Moon?
It probably formed as a result of a giant impact.
approximately 10 Earth-mass corestrong atmospheric winds and storms orbited by rings of ice and rock magnetic field stronger than Earth's
Jovian Planets
one of the galielean moons: volcanoes currently erupting,
Lo
dust particles entering Earth's atmosphere at high speed visible in the sky as a bright streak of light for only a few seconds
METOERS
Which of the following objects are probably not located in the same region of the solar system in which they originally formed?
Oort cloud comets
Which of the following is a real piece of evidence pointing to geological activity on Pluto?
Surface regions that suggest glacial movement of frozen ices of nitrogen and methane.
Suppose that a white dwarf is gaining mass through accretion in a binary system. What happens if the mass someday reaches the 1.4 solar mass limit?
The white dwarf will explode completely as a white dwarf supernova.
Why do astronomers believe that Triton is a captured moon?
Triton orbits Neptune in a direction opposite that of Neptune's rotation.
The two jovian planets that contain the highest proportions of hydrogen compounds are ___________.
Uranus and Neptune
Its density would increase, but its diameter would barely change.
What would happen to Jupiter if we could somehow double its mass?
The three layers represent clouds made of gases that condense at different temperatures.
Why does Jupiter have three distinct layers of clouds?
What kind of gas cloud is most likely to give birth to stars?
a cold, dense gas cloud
What is a meteorite?
a fragment of an asteroid from the solar system that has fallen to Earth's surface
What is the Cassini division of Saturn's rings?
a large gap, visible from Earth
A rock found on Earth that crashed down from space is called ______.
a meteorite
The fact that most moons always show the same face to their planet is
a natural consequence of tidal forces acting on the moons.
The number of comets in the Oort cloud is probably about
a trillion.
What kind of star is most likely to become a white-dwarf supernova?
a white dwarf star with a red giant binary companion
A(n)___________ consists of hot, swirling gas captured by a white dwarf (or neutron star or black hole) from a binary companion star.
accretion disk
Where are the Trojan asteroids located?
along Jupiter's orbit, 60° ahead of and behind Jupiter
What is the basic definition of a black hole?
any object from which the escape velocity exceeds the speed of light
The asteroid belt is located ______.
between the orbits of Mars and Jupiter
A ____ is a "star" so small in mass that its core never gets hot enough to sustain nuclear fusion reactions.
brown dwarf
How do astronomers think Jupiter generates its internal heat?
by contracting, changing gravitational potential energy into thermal energy
Halley's comet is named after the English scientist Edmund Halley because he
calculated its orbit and predicted that it would return in 1758.
The energy that drives the expansion of a star into a subgiant or red giant comes from
carbon fusion
Processed meteorites with low metal content probably are
chunks of a larger asteroid that was shattered by a collision.
A ____ consists of two stars that orbit each other every few days
close binary
jupiters three layers of clouds include
clouds of ammonium hydrosulfide clouds of ammonium clouds of water
Comets with extremely elliptical orbits, like comets Hyakutake and Hale-Bopp,
come from the Oort cloud.
Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they
contain a noticeable fraction of pure metallic flakes.
A "star" with a mass below 0.08 solar mass has its gravitational contracted halted by _____ .
degeneracy pressure
As a protostar shrinks in size, its central temperature rises along with its
degeneracy pressure
1. The radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of
electron degeneracy pressure.
A comet entering the inner solar system from afar will __________.
form a coma and some time later form a tail
The collapse of a protostar with less than 0.08 times the mass of the Sun is halted by
gravitational equilibrium
The basic requirement for a cloud to collapse to form a star is that __________.
gravity must be strong enough to overpower the cloud's internal pressure
a long-lived, high-pressure storm on Jupiter
great red spot
When it dies, a high-mass star explodes as a
helium fusion
The final stage of core fusion in a low-mass star is
high-mass stars
A star that is expanding (into a subgiant and then a giant) has a(n)
hydrogen shell fusion.
If you wanted to observe stars behind a molecular cloud, in what wavelength of light would you most likely observe?
infared
When do comets generally begin to form a tail?
inside of Jupiter's orbit
Star-forming clouds appear dark in visible-light photos because the light of stars behind them is absorbed by __________.
interstellar dust
Mass can be lost through a _____ of material ejected along a protostar's axis of rotation.
jet
composed mostly of hydrogen and helium
jupiter and saturn
interior is mostly liquid or metallic hydrogen
jupiter and saturn
Which of the following is most unlikely to be found on Titan?
lakes of liquid water in the warmer equatorial regions
saturns rings are composed of
little particles of ice and rock
When it dies, a low-mass star expels a
low mass star
Stars with mass greater than about 8 solar masses are considered
main sequence star
occurs when fusion creates iron in the core of a star.
massive star supernova
The Sun formed, probably along with other stars, within a large ____
molecular cloud
A 10-solar-mass main-sequence star will produce which of the following remnants?
neutron star
Stars that are fusing hydrogen in their cores are
neutron star
What is the most abundant gas in Titan's atmosphere?
nitrogen
occurs when hydrogen fusion ignites on the surface of a white dwarf in a binary system.
nova
The Schwarzschild radius of a black hole depends on ________.
only the mass of the black hole
Gaps in the asteroid belt (often called Kirkwood gaps) are caused by ______.
orbital resonances with Jupiter
A typical shooting star in a meteor shower is caused by a ________ entering Earth's atmosphere.
pea-size particle from a comet
the expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star
planetary nebula
charon
plutos largest moon
Which of the following sequences correctly describes the stages of life for a low-mass star?
protostar, main-sequence, red giant, white dwarf
Planets may form within the ____ that surrounds a forming star.
protostellar disk
Most of the gas remaining from the process of star formation is swept into interstellar space by a ____
protostellar wind
Most meteorites are
rocky and primitive.
Degenearcy pressure arises when ________.
subatomic particles are packed as tightly as the laws of quantum mechanics allow
Stars with masses less than about two solar masses are considered
supernova
When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called _____.
the coma
The interstellar clouds called molecular clouds are _______.
the cool clouds in which stars form
nucleus
the frozen portion of a comet
When you see the bright flash of a meteor, what are you actually seeing?
the glow from a pea-size particle and the surrounding air as the particle burns up in our atmosphere
What part of a comet points most directly away from the Sun?
the plasma tail
A star is born when it comes into ________________, in which the energy released by fusion matches the energy it radiates into space.
thermal pressure
As a protostar's internal temperature increases, its growing ___ helps slow its contraction due to gravity.
thermal pressure
Scientists have detected lakes of liquid methane and ethane on the surface of
titan
blue color because of methane
uranus and neptune
composed mostly of hydrogen compounds
uranus and neptune
When does a star become a main-sequence star?
when the rate of hydrogen fusion within the star's core is high enough to maintain gravitational equilibrium
A white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the
white dwarf limit (1.4 solar masses).
