Physical Science - Chapter 14: The Universe
Click and drag on elements in order Rank the stars in order of their surface temperatures, with the hottest at the top.
- A blue main sequence star - A yellow main sequence star - An orange giant star - A red giant star
Select all that apply Which of the following are components of the Big Bang theory?
- At the moment of the Big Bang, the energy that would become matter filled the space with light. - The current laws of physics cannot explain the behavior of whatever came before the Big Bang.
Match the regions of a typical star with their descriptions. Instructions
- Core --- The density is 12 times that of lead; nuclear fusion releases energy here. - Radiative zone --- The gas doesn't move much, but photons frequently interact with gas. - Convection zone --- Heated gas rises, expands, and radiates energy, then sinks again. - Surface --- Photons are emitted but not reabsorbed and carry energy outward.
Select all that apply Select all of the following properties that determine a star's apparent brightness.
- Distance of the star - Luminosity of the star
Match the terms related to the celestial sphere to their definitions. Instructions
- North celestial pole ---- The point on the celestial sphere directly above the North Pole of Earth - Celestial equator --- A line on the celestial sphere in the same plane as Earth's equator - Celestial meridian --- A line that runs from north to south, crossing directly overhead and through the celestial poles - Altitude --- How high above the horizon an object is
Click and drag on elements in order Rank the following stars by their life spans, with the shortest living star on top of the list.
- Star 10 times more massive than the sun - Star two times more massive than the sun - star with a 10-billion-year life span - Star with 20-billion-year life span
Select all that apply Select all the true statements about the magnitude system for measuring the brightness of stars.
- The apparent magnitude depends, in part, on the distance to the star. - Brighter objects have smaller magnitude numbers. - Absolute magnitude is based on a star's luminosity.
Select all that apply The mass of a star is important because it determines Blank______.
- the way the star will die - how long a star will live - its location on the H-R diagram
Select all that apply A light-year is Blank______.
-sometimes abbreviated as "ly" -a unit used for measuring large distances -the distance that light travels in one year
Click and drag on elements in order Arrange the steps to show the life cycle of a Sun-like star, with the first at the top of the list.
1. interstellar cloud 2. main-sequence star3. red giant4. planetary nebula5. white dwarf
If the difference in the apparent magnitudes of two stars is 5 (for example, a star with a -1 magnitude and a star with a +4 magnitude), then they differ by a factor of Blank______ in brightness.
100
If the difference in the apparent magnitudes of two stars is 5 (for example, a star with a -1 magnitude and a star with a +4 magnitude), then they differ by a factor of Blank______ in brightness.
100 Reason: Each step in magnitude corresponds to a star being 2.512 times brighter. Five steps is a factor of 2.5125 = 100. TEXBOOK: tODAY, A FIRST-MAGNITUDE STAR IS DEFINED
Match the numerical values to the properties of the Milky Way galaxy.
100 billion 100 billion Drop zone Number of stars correct Toggle Button Unavailable. Number of stars 100,000 100,000 Drop zone Width of the disk, in light-years correct Toggle Button Unavailable. Width of the disk, in light-years 200 million 200 million Drop zone Period of the Sun's orbit in years correct Toggle Button Unavailable. Period of the Sun's orbit in years 30,000 30,000 Drop zone How far the Sun is from the center in light-years correct Toggle Button Unavailable. How far the Sun is from the center in light-years
Match the stars to their typical lifetimes on the main sequence.
15 solar masses ---- About 10 million years 1 solar mass --- About 10 billion years 0.1 solar mass --- About a trillion years
If Sirius has an apparent magnitude of +1 and Jupiter has an apparent magnitude of +2, how many times brighter is Jupiter?
2.51 Reason: Each step in magnitude represents a 2.51 times increase in brightness.
Outside of the Milky Way, the nearest galaxy is Blank______ light-years away.
25,000
When a massive star dies, gravity will overcome all forces between nuclear particles and a black hole will result if the star's core is a minimum of about Blank______ solar masses.
3 Reason: Such a large core is left behind only by very massive stars (perhaps 20 solar masses and up).
Two stars, A and B, have the same apparent brightness. If you know from measuring spectra that star A is 10 times more luminous than B, then you can conclude that Blank______.
A is farther away than B
Select all that apply Select all the events that occur in the late life stages of both high-mass and low-mass stars.
A second red giant is formed. The radius and color change. Hydrogen or other elements fuse in shells around the core.
Match the stars with their approximate surface temperatures.
A yellow star --- 5,000 K A blue star --- 30,000 K A red star --- 2,500 K A white star --- 7,500 K
Our most well-supported view of how our universe formed describes the expansion and formation of matter and energy from a point so small and dense that modern physics cannot explain its behavior; it is known as the Blank______ theory.
Big Bang
Variable stars that are used to determine distance are known as __________ variable.
Blank 1: Cepheids or Cepheid
The measurement of the brightness that a star appears to have in the night sky is its _____________ magnitude.
Blank 1: apparent
The arrows in the figure indicate stars that are primarily part of the of this spiral galaxy.
Blank 1: disk, disc, galactic disk, or galactic disc
The vast majority of energy emitted from a star originally comes from ___________ being converted into _________ and releasing energy in the process. When the star begins to collapse this reeaction continues in the shell of the core.
Blank 1: hydrogen Blank 2: helium
The total light output of an object is known as its ___________.
Blank 1: luminosity
Most stars on the H-R diagram are found along the diagonal purple line, which is known as the _______________ _________________.
Blank 1: main Blank 2: sequence
The blown-off outer layers of a dying low-mass star form a(n) ________ nebula.
Blank 1: planetary
The Sun is currently about halfway through its time on the main sequence. When it moves off the main sequence, first it will become a(n)_______ giant and then a(n) _________ dwarf.
Blank 1: red Blank 2: white
Our galaxy is categorized as a _____________ galaxy, whereas most galaxies in the universe are elliptical.
Blank 1: spiral
When a massive star dies, it explodes as a(n) _________. The explosion may leave behind a dense stellar remnant called a(n) ________ star, or the core may collapse completely into a black hole.
Blank 1: supernova Blank 2: neutron
Using Wien's law, the maximum wavelength of light most intensely emitted by a star is inversely proportional to the star's __________.
Blank 1: temperature
The horizontal axis (across the bottom) for an HR diagram is labeled as ____________ type.
Blank 1: temperature, spectra, or spectral
The nearest star to Earth is about four light-years away. This means that if a giant flare erupted from that star today, we would see the effect Blank______.
FOUR YEARS FROM NOW
Match the main sequence star with the approximate lifetime on the main sequence.
G-type stars (such as the Sun) -- 10 billion years O-type stars --- 10 million years B-type stars --- 100 million years K-type stars --- 100 billion years
Match the terms related to galaxies to their definitions.
Galaxy matches Choice A collection of 100 billion gravitationally bound stars, gas, and dust Globular cluster matches Choice A collection of up to 1 million gravitationally bound stars Solar system matches Choice A star and the objects gravitationally bound to it Universe matches Choice Everything known to exist: all of space and all the galaxies within it
Match the parts of a spiral galaxy to their descriptions.
Halo matches Choice A large spherical area containing globular clusters and dark matter Disk matches Choice A flat, rotating collection of stars, gas, and dust a 100,000 light-years in diameter Nucleus matches Choice The core of a galaxy, where a huge black hole is often found Spiral arm matches Choice A locally dense strip of stars and gas in the disk
Match the elements to where they are or were created.
Helium matches Choice Stars and the Big Bang Carbon, calcium, silicon, and iron matches Choice The cores of massive stars when they are red giants Gold, silver, and uranium matches Choice In material compressed and heated in supernova explosions
Select all that apply Select all that are types of galaxies.
Irregular correct Elliptical correct Spiral
Click and drag on elements in order Based on the spectral classification of stars rank the following stars' temperatures from hottest to coolest, placing the hottest star on top of the list.
O B A F G K
Click and drag on elements in order Sequence the formation of a Sun-like star from the first phase to the last phase, starting with the first phase on top of the list. Instructions Choice 1 of 4. Protostar toggle button Protostar Choice 2 of 4. Main sequence star toggle button Main sequence star Choice 3 of 4. Red giant star toggle button Red giant star Choice 4 of 4. White dwarf toggle button White dwarf
Protostar Main Sequence star Red giant star white dwarf
The arrow on the figure indicates which layer of the Sun?
Radiation zone
If the blueish star Regulus is many times hotter than the reddish star Aldebaran, how can the two stars have the same luminosity?
Red stars have to be larger to have the same luminosity.
Click and drag on elements in order Rank order the following objects based on their apparent magnitude, with the brightest-appearing object on top of the list.
SUN FULL MOON VENUS SIRIUS PLUTO
Our galaxy is categorized as a ____________ galaxy, whereas most galaxies in the universe are elliptical.
Spiral
Using the diagram, match the category of star types to the star(s) described.
Sun -- Main sequence Sirius B -- White dwarf Aldebaran -- Red giant Antares -- Red supergiant
Match the terms related to the death of a massive star to their definitions. Instructions
Supernova Supernova Drop zone An explosion of a massive star correct Toggle Button Unavailable. An explosion of a massive star Black hole Black hole Drop zone A singularity: a point in space-time so massive that it warps space so that light cannot escape correct Toggle Button Unavailable. A singularity: a point in space-time so massive that it warps space so that light cannot escape Neutron star Neutron star Drop zone A superdense remnant of a massive star's core about the size of a city correct Toggle Button Unavailable. A superdense remnant of a massive star's core about the size of a city Pulsar Pulsar Drop zone A strongly magnetized, rapidly spinning neutron star correct Toggle Button Unavailable. A strongly magnetized, rapidly spinning neutron star
Click and drag on elements in order Place the Sun's layers in order with the outermost layer on top of the list and the innermost at the bottom. Instructions Choice 1 of 4. Surface toggle button Surface Choice 2 of 4. Convective zone toggle button Convective zone Choice 3 of 4. Radiative zone toggle button Radiative zone Choice 4 of 4. Core toggle button Core
Surface Convective Zone Radiative Zone Core
You observe two stars that are known to be identical. One is three times farther away from you than the other. How do their luminosities compare?
The luminosities are the same. Reason: Luminosity measures how much light a star emits, and these two stars are identical. The more distant one will look fainter but only because it is farther away.
Red giant stars burn helium into carbon in the core and hydrogen into helium outside it. This produces more luminosity than when the star was on the main sequence, but the surface is cooler. Why is this?
The star expands. Spreading the radiation over the larger surface means the surface can be cooler. correct Reason: The whole star produces more light than before (so it is very bright), but each part of the surface is not as hot.
What is Wien's displacement law?
The temperature of a gas, including stars, is inversely proportional to the peak wavelength it produces.
What is a star's luminosity?
The total amount of energy radiated into space each second from the surface of the star.
If only elements lighter than iron can undergo fusion efficiently in stellar cores, where do heavier elements such as gold or plutonium come from?
They are produced in blast waves of supernovas. Reason: The energy of the extremely violent explosion can create elements through fusion reactions that require energy to be input rather than release it.
True or false: A white dwarf is the final stage of existence for most stars.
True
True or false: A white dwarf is the final stage of existence for most stars.
Truecorrect Reason: The white dwarf is the last stage in the lifetime of a medium- or low-mass star.
Click and drag on elements in order Rank the objects so that each contains all the objects below it.
Universe Galaxy Solar system stars
The most massive stars are found on which part of the main sequence band in H-R diagram?
Upper-left corner
Which of the following is not a possible end-state phase of a high-mass star?
White dwarf Reason: A white dwarf is a possible end-state phase for a low-mass star.
Which of the following is not a possible end-state phase of a high-mass star?
White dwarf Reason: A white dwarf is a possible end-state phase for a low-mass star.
Compared to the range of other sized stars in our galaxy, the Sun has Blank______.
about average size, mass, and lifetime Reason: The Sun is a pretty typical star.
When considering our galaxy, the Sun and solar system planets are located Blank______.
about halfway out from the center
In terms of its mass, the Sun is a(n) Blank______ star.
average Reason: The Sun is a very typical star. Most stars are about the mass of the Sun or smaller.
The different shapes of galaxies (irregular, elliptical, spiral) are believed to Blank______.
be the result of the way the galaxies formed Reason: Mergers and interactions between galaxies can cause them to change type.
The different shapes of galaxies (irregular, elliptical, spiral) are believed to Blank______.
be the result of the way the galaxies formed correct Reason: Mergers and interactions between galaxies can cause them to change type.
Select all that apply Stars that are found on the main sequence can be characterized as Blank______.
being in the "normal" phase of their lives being in the longest phase of their lives being the most common type of star in our galaxy
A red giant star Blank______.
can be 100 times larger (in radius) than the Sun
The arrow on the diagram of the celestial sphere indicates the Blank______.
celestial North Pole
When fusion is unable to supply further energy in a massive star, the core Blank______.
collapses, and the outer layers collapse onto it Reason: The collapsed star then rebounds outward in a supernova explosion
When fusion is unable to supply further energy in a massive star, the core Blank______.
collapses, and the outer layers collapse onto it correct Reason: The collapsed star then rebounds outward in a supernova explosion.
White dwarfs are all of the following except Blank______.
cool at the surface
The arrows in the figure indicate stars that are primarily part of the of this spiral galaxy.
disk
The brightest planets observed in the night sky without a telescope Blank______.
do not twinkle Reason: The stars seem to twinkle because density differences in the atmosphere refract the point of starlight one way, then the other, as the air moves. A planet does not seem to twinkle because it appears as a tiny disk of light rather than a point source, so refraction from moving air of different densities does not affect the image as much.
The nearest star to Earth is about four light-years away. This means that if a giant flare erupted from that star today, we would see the effect Blank______.
four years from now Reason: It will take four years for the light from the flare to travel a distance of four light-years, since light can travel a distance of one light-year in one year.
The continued existence of a star in any phase of its evolution is a balance between the inward pressure from Blank______ and the outward pressure of Blank______.
gravity; expansion Reason: Gravity acts to collapse a star. The gas of the star is heated by the energy from fusion in the core, creating outward pressure to oppose the force of gravity.
When a star is stable, at each layer inside the star, the inward pull of gravity from the material above Blank______.
is balanced by the outward pressure of hot gas inside that layer
A nebula becomes a protostar when it Blank______.
is dense enough to sustain nuclear reactions
The microwave background radiation studied by the COBE and WMAP missions supports the Big Bang theory because Blank______.
it implies that the early universe was very uniform, hot, and dense Reason: The radiation fills space and would have had a much higher temperature when it was emitted if we adjust for the cooling from the expansion of the universe.
The factor that has the greatest effect on a main sequence star's lifetime and evolution is its Blank______.
mass
The factor that has the greatest effect on a main sequence star's lifetime and evolution is its Blank______.
mass Reason: The mass determines a star's rate of fuel consumption.
Compared to the Sun, a blue main sequence star will have Blank______.
more mass, perhaps 10 times more Reason: Blue main sequence stars are the most massive.
Compared to the Sun, a blue main sequence star will have Blank______.
more mass, perhaps 10 times more correct Reason: Blue main sequence stars are the most massive.
The largest diameter stars are the Blank______.
red supergiants
Compared to the Sun's 10-billion-year life span, a star that has 10 times the Sun's mass will have a life span that is Blank______.
significantly shorter Reason: A more massive star has a larger core but must support its extra mass against gravity. That requires more power and results in a shorter lifetime. A 10-solar-mass star will last about 30 million years; very massive stars only last a few million years.
The property of a star that most directly affects its color is the star's Blank______.
surface temperature Reason: Wien's law tells us that there is a direct relationship between the temperature of a dense, glowing object (a blackbody) and the peak wavelength (color) of its radiation.
The stellar spectral classification scheme, O B A F G K M, is based on differences in stellar spectra caused primarily by differences in the Blank______ of stars.
temperature
A star becomes a red giant when it exhausts the useful hydrogen in the core. Hydrogen is fused in a shell around the core because Blank______.
the core collapses a bit once fusion isn't efficient, heats, and new material moves in from outside correct Reason: The core and the layers around it collapse a bit. Then, shell fusion around the core and helium fusion in the core restabilize the star.
A planetary nebula is all of the following except Blank______.
the remains of a planet
A planetary nebula is all of the following except Blank______.
the remains of a planet correct Reason: They were discovered in the early days of telescopes and looked somewhat like planets; hence, the misleading name.
The idea that the universe is expanding means that Blank______.
the volume of space is expanding, and it carries the galaxies in the universe along with it
Black holes are called black holes because Blank______.
their gravity warps space so strongly that even light cannot escape them
Stars in the night sky appear to twinkle because Blank______.
their light is refracted by a series of moving pockets of air in the atmosphere
Cepheid variable stars are useful in astronomy because Blank______.
their period allows us to measure distances
