WSU astronomy 135 Final exam Flashcards

Terms Definitions
Interstellar medium
At the end of their lives, stars expel a large amount of their mass...
very hot gasses
stars are made of...
hydrostatic equilibrium
what is it called when stars try to be in equilibrium
the outward pressure equals the inward pressure
what does it mean to be in hydrostatic equilibrium
the inward pressure on a star is due to what?
gas and radiation pressure
The outward pressure on a star is do to what two things?
an explosion
What is an example of something that may happen if a star is attempting to return to equilibrium
When gas heats up it ...
increases the outward pressure
when the gas expands how it does what that allows it to cool down
molecular clouds
Where are stars born?
Collision between two clouds
What three things can trigger the formation of a star
Radiation from a group of bright stars
The shock wave of a supernova explosion
What three events can trigger the compression of a cloud which intern stimulates star formation
the gas is not cool enough
What characteristic of the gas in a molecular cloud that causes the motion of the particles will prevent the contraction and gravity cannot win over gas pressure
Jeans mass
the mass of the material that starts to condense gravitationally must exceed to limiting mass called...>
dense cores
Inside giant molecular clouds, hundreds or thousands of ... exist. Each one of these ... will form a star
Infrared wavelengths are not absorbed by the dust
Why does infrared observations allow us to look inside a molecular cloud
what cores are thousands of times bigger than the solar system?
Temperature and pressure
what two things increase in a cloud as it collapses?
As a cloud is collapsing what is broken apart?
Atoms are ionized
What is the final stage in the formation of a star that causes the molecular cloud to collapse
In the beginning of as stars life when the mass accretes in the central region the newly forming object at the center is known as a ...
Gravitational compression
In the beginning stages of a star what generates the heat that causes the star to glow
More massive stars
Which star forms more rapidly... Less massive or more massive stars
radiation pressure and the stellar wind that has formed
What stops the protostar from building mass
Radiation blows the rest of the mass away
Why do stellar winds and radiation pressure contribute to stopping the mass accumulation of a protostar
Pre-main sequence star
What is the phase after a Protostar when the mass accretion has stopped accumulating?
Less massive stars
What stars are brighter in the Pre-main sequence phase... Less massive or more massive stars
Hydrogen fusion
What occurs in the core of a pre-main sequence star when it reaches ~10 million degrees?
Hydrogen fusion
What is the final step before a main sequence star is born?
Fusion of hydrogen and helium
What is hydrogen fusion? (What is the significants of ~10 million degrees?)
The evolution of stars
What does the equation of hydrostatic equilibrium and the calculations of the change in luminosity of the contracting star allow astrophysicists to model?
Evolutionary tracks
What plot the changing position of a star on the Hertzprung Russell diagram?
Temperature and luminosity change
What do Evolutionary tracks display as the star evolves into and out of the main sequence?
Brown dwarfs
What is created from pre-main sequence star with mass under .08 solar masses that don't have enough mass to ignite Hydrogen fusion?
initial mass and chemical composition
What two things does the evolution on a star rely on?
Determines the amount of hydrogen available for fuel
Why does initial mass matter in the evolution of a star?
How fast the hydrogen is consumed
How is luminosity the evolution of a star effected?
Star's mass over Star's luminosity
Star's lifetime is determined by....
Core pressure and temperature
What two things in the core of a main sequence star are determined by its mass?
Stars of higher mass have higher core temperature and thus more rapid fusion, making those stars more luminous and causes them to have a ... life span. Shorter or Longer?
Stars of lower mass have cooler cores and slower fusion rates, giving them smaller luminosities and .... lifetimes. Shorter or Longer?
Fusion of hydrogen into helium takes longer than the fusion of helium into heavier elements
Why does a star spend the majority of its life in the the main sequence?
What percentage of hydrogen is converted into helium in the main sequence stage?
Seeing the changes in position on the H-R diagram
After hydrogen is depleted in the core, How can we follow the star's evolution?
As the thermonuclear reactions change the chemical composition of the star, the star must ... in the H-R diagram.
Thermonuclear reaction
What reaction in a main sequence star cause the change in the chemical composition of a star?
Core density increases (four H nuclei fuse into one He nucleus) and temperature increases
What two things happen in the core of a star as the hydrogen is converted to helium?
As a star leaves the main sequence the rate of thermonuclear reactions... increases or decrease?
The star brightens
What is caused from the increase in thermonuclear reactions in the star as it leaves the main sequence?
Over the past 4.6 billion years the Sun's luminosity has been steadily.... increasing or decreasing?
In low mass stars heat is transferred by .... throughout the whole star
hydrogen is eventually cycled throughout the whole star
What is the meaning of convection?
The stars contracts and heats up
In a low mass star, what two things happens when the rate of fusion ceases in the core?
What causes a low mass star to heat up and contracts as once it has ceased the rate of fusion?
White dwarf
The post main sequence of a low mass star which is an ember of helium that cools for eternity
Hydrogen fuses in a shell around the core
In a intermediate mass star when does the stars temperature stop rising in the post main sequence?
In a post main sequence low and intermediate mass star, what does the hydrogen burning shell stop the star from doing?
continues to expand and cool
Because a Intermediate mass star in post main sequence is unable to collapse what happens?
red giant
What do post main sequence intermediate mass stars become after they have increased?
helium flash
What happens if a intermediate mass stars core continues to contract and fuse with a core temperature of 2 M sun?
Triple-alpha reaction
Whats another word for the helium fusion reaction?
Helium fusion
As the core of a Post Main sequence Intermediate mass star what happens when the core temperature reaches 100 million K due to the contracting core?
As the star shrinks it get... hotter or colder?
temperature decreases
luminosity increases
The higher temperature in a intermediate mass star makes the star expand which does two things to the temperature and luminosity?
will contract
What will happen in the core of a red giant once the Helium is depleted (leaving carbon/ and oxygen)?
Planetary nebula
What is created when a red giant becomes unstable and detaches its atmosphere?
white dwarf
What does a red giant die as once it has detached its atmosphere?
How is a high mass star able to have gravity ignite other thermonuclear reactions once helium fusion ends?
red supergiant
What becomes of high mass stars in the post main sequence?
supernove explosion
What is the death of a supergiant when an inert, iron rich core builds up?
The protons and neutron are so tightly bound that no further energy can be extracted
Why can Iron not fuel further thermonuclear reactions in the death of a red supergiant because Iron need energy put into it for a reaction?
Elements heavier than iron
What fuses during a supernova explosion in a red supergiant?
Neutron star
What does the star die as that has a remnant mass of between 1.4 and 3 Msun?
Black hole
What does the star die as that has a remnant mass of between 3 and greater Msun?
Stellar evolution
What is another name for the life cycle and evolution of a star?
10 billion years
How long will a 1Msun star spend in the main sequence (The Sun)?
Forms stars
What happens to the gas expelled into the interstellar medium?
What is a large collection of stars, gas and dust bound together by gravity?
Milky Way
What is the galaxy we live in?
Looked like a flowing ribbon of milk
How did Greeks get the name the Milky Way for our galaxy?
Interstellar medium
What are the dust clouds and other clouds of gas out of which new stars are formed?
200 billion stars
How many stars the milky way contain?
disk shaped
What is the main feature of the MIlky way galaxy?
They contain very few elements heavier than helium
How do we know that the galactic halo and in globular clusters are older?
Which direction do the stars orbit the galactic center?
Who discovered with his telescope that the celestial fluid (The Milky Way) could be resolved into innumerable faint stars?
Who discovered that our galaxy was a disk of stars?
Who discovered Uranus?
Who took the first astrophoto (of the moon)?
21-cm radio radiation
The detection of WHAT advanced the mapping of the milky way?
How is 21-centimeter radiation produced?
What percent of the universe does hydrogen make up?
Not absorbed by the dust
What characteristic allow the 21-cm radiation to go much larger distances than optical wavelengths?
what property do electrons and protons share?
It is observable at radio wavelengths
Why is it important that when protons and electrons spin in opposite directions in a hydrogen molecule they emit a wavelength equal to 21 centimeter?
emission nebulae
What is a cloud of ionized hydrogen atoms that glow because of ultraviolet radiation from very hot stars embedded in them?
Orbits of stars at different distances from the galactic center
what measurements would allow us to to determine the complete distribution of mass in the Milky Way?
Measure the doppler shifts and use geometry
How do astronomers use radio waves at 21 cm to measure the velocities of clouds of atomic hydrogen?
Rotation curve
What is the graph called that Astronomers plot the rotational velocity of stars or gas clouds vs. their distance for the galactic center?
The halo that surround the Milky Way
Where is the most mass located in our galaxy?
10 times the total mass of stars in the disk
The amount of more mass outside the milky way than in?
Dark matter
The mass out side of our solar system that has no radiation?
Its gravitational influence on regular matter
How do we know dark matter exists?
What percentage of other dark matter is in other galaxies?
They are absorbed by the dust
what characteristic do optical wavelengths have that make them unable to observe the galactic center?
black hole
What is the orbital mass of the center of the galaxy is 4 million solar masses which indicate that the center is a ... ?
Spirals (spiral)
Barred Spirals (part spiral)
Ellipticals (egg)
Lenticulars (UFO)
Irregulars (Spread out)
What are the 5 types of galaxy is this?
gravitationally bound
Majority of galaxies are found within groups or cluster that are ...?
What type of galaxy is more common in huge clusters of galaxies?
Local Group
What group of 40 galaxies does the Milky Way belong to?
Clusters of galaxies are grouped into ...
Huge volumes in the universe between galaxies that are nearly empty of matter
Starburst galaxies
What is created when two galaxies collide causing interstellar clouds to collide and the gas to cool and form stars?
Galactic merger
What happens when two galaxies of approximately the same size collide and then merge?
Galactic cannibalism
What happens when one larger galaxy collides with a much smaller one and the smaller one becomes part of the larger one?
Both galaxies are stripped of their gas and dust
What happens when two galaxies collide violently?
WIMPs (Weakly interacting massive particles)
massive subatomic particles that have no charge, cannot produce photons and rarely interact and exchange energy with other particles.
MACHOs (Massive compact halo objects)
Brown dwarfs, main sequence stars or Jupiter sized objects are all examples of ordinary matter. What is another word for ordinary matter like this?
Active galactic nucleus
What is the name for a galaxy with an extremely bright center?
A small radio component in the center of the galaxy where a supermassive black hole is located
Where do electron come from?
What are the most luminous examples of active galactic nuclei?
what wavelength of the electromagnetic spectrum do Quasars radiate from?
What is the study of the origin, structure, and evolution of the universe?
Cosmological constant
What term described in Einstein's theory of relativity implies that the universe must expand or contract?
The Big bang
The event that marks the beginning of the universe, creating all space, matter, radiation and energy within it was called?
The big bang
The expansion of the universe, the cosmic microwave background radiation, and the amount of hydrogen and helium present in the universe can all be explained by what theory?
The faster it moves away
What is the meaning of Hubble's discovery that the more distant the galaxy, the greater its redshift?
Hubble Law
Law that states the linear relationship between distance and speed.
72 km/s
If Hubble's constant is 72 km/s/Mpc or 22 km/s/Mly and recessional speed is Hubble's constant times distance... How much does the recessional speed increase if you increase the distance by One megaparsec?
22 km/s
If Hubble's constant is 72 km/s/Mpc or 22 km/s/Mly and recessional speed is Hubble's constant times distance... How much does the recessional speed increase if you increase the distance by One megalight-year?
Stretch to longer wavelengths
What effect on the wavelength does the expansion of the universe have on photons?
Doppler redshift
Stretch of an object caused by an object's motion through space
Cosmological redshift
Stretch of an object caused by the expansion of space
They used to be closer together
Based on Hubble's law, what conclusion can we draw about the distance of galaxies in the past?
They used to be closer together
Based on Hubble's law, what conclusion can we draw about the distance of matter in the past?
The age of universe
What significant fact can we find by calculating the velocity of the galaxies moving away from us and finding when they were at one point all together?
Cosmic background radiation (microwave background radiation)
The left over radiation from the Big Bang that cooled as the universe expanded and the cosmological redshift stretched the wavelength radiation is called...
Cosmic background radiation
The tv static on the a channel with no reception is an example of...
It was lumpy (Not perfectly uniform)
What conclusion can we draw from the fact that their were slight temperature variation in the early universe?
The four forces of nature
What is the name given to the Gravitational, Electromagnetic, Strong nuclear, and weak nuclear forces?
The four forces of nature are distinct at low temperatures but ... at high temperatures?
Grand Unified Theory
The theory that suggests that after the elecromagnetic and weak nuclear force have already been merged, at even higher temperatures, the electroweak and the strong nuclear forces also merge into one.
Particle era
The era close to the beginning of time in which the amounts of matter and antimatter were nearly equal?
Antimatter has the same properties as matter except for ...?
Planck Era
What was the era was when gravity separated from the "super force (??)"
The fact that The same microwave background temperature is observed in all directions is called ....?
The sudden expansion of the universe that lasted a brief period shortly after the Big Bang.
Spacetime would curve
According to Einstein's theory of general relativity, if the universe is not flat and the kinetic energy of expansion does not equal the overall gravitational pull of the universe than what happens?
Critical density
The precise density that marks the transition between eternal expansion and eventual contraction?
The rate of expansion is increasing
What does the 1998 observation that supernova were dimmer than expected (farther than expected) imply?
Heat death
Once the galaxy has expanded for a infinite amount of years everything will be so spread out that galaxies will be exhausted, star formation will cease and all objects will reach the same temperature resulting in what is called a ....?
14 billion
age of the universe? Hubble constant?
Three shortcomings of the big bang theory
Why the universe is isotropic, How structure arose in the universe, and why the geometry of the universe is approximately flat are all what?
the past few decades
Old exam 1: When did scientific thinking begin?
predicts new observations
Old exam 1: The best test of a scientific theory is how well it....?
The distance that light travels in one year
Old exam 1: One light year is?
Old exam 1: If the figure is pointing away from the Celestial sphere which direction is he pointing?
90 degrees
Old exam 1: A long thin cloud that stretched from your zenith to the western horizon would have an angular size of...
Old exam 1: Imagine that you see the crescent moon in the western sky and it is right next to a bright star. If you go out the next day in the evening in which direction would the moon have moved with respect to that star?
It will be smaller
Old exam 1: Ever since the Moon formed it has been receding from Earth. What does this mean about it angular size in the future?
Old exam 1: If you were on the Moon looking at the Earth during a total solar eclipse, the phase of Earth would be...?
Waxing Gibbous
Old exam 1: Full moon will be on Friday feb 18. What is the phase of the moon today? (Test taken on the 14th)
Warmer than florida
Old exam 1: If the Earth's axis were tilted 90 degrees what would happen to the arctic circle in the summer?
Sun would never shine
Old exam 1: If you live on the equator the what characteristics would the sun have more than 23.5 degrees away from your zenith?
Old exam 1: If it were possible to always have the same number of daylight hours throughout the year, but the earth's axis were still tilted 23.5 would we still have seasons?
Old exam 1: When it is fall in the northern hemisphere what season is it in the southern hemisphere?
Fall and winter (excluding the fall equinox)
Old exam 1: During which time(s) of the year does the Sun rise south of east?
January 1992
Old exam 1: One of the longest total solar eclipses happened on July 11, 1991. The solar eclipse that followed was annular; it was also one of the longest. When did the annular eclipse occur?
Their orbits are smaller than Earth's orbit, so they're never opposite the Sun
Old exam 1: Mercery and Venus are never seen at midnight because...?
The Moon's rotational and orbital periods are equal
Old exam 1: We see the same face of the Moon because?
retrograde motion
Old exam 1: A reversal in the apparent direction of motion of a planet against the background stars?
The wavelength of a wave
Old exam 1: The distance between two adjacent peaks of the wave?
**** NO
Old exam 1: Do gamma rays travel faster than radio because they carry more energy?
Old exam 1: The speed of light is ... of wavelength? dependent or independent
Old exam 1: The energy of a wave ... if the frequency of the wave increases? increases or decreases
Old exam 1: Infrared light has a ... wavelength than visible light? Longer or shorter
Old exam 1: X-rays are ... energetic than ultraviolet light? More or less
Old exam 1: What is the name of a light particle?
reflects visible light
Old exam 1: We can see the moon in the sky because it...?
Old exam 1: If a line in a spectral curve is steadily rising and dips to 0 Energy outputs per second for Blue and Orange it means that Blue and Orange have been...? absorbed or not absorbed
2 hertz
Old exam 1: Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. This means that the leaf has a frequency of...?
absorption line spectrum
Old exam 1: When white light passes through a cool cloud of gas we see..?
Ionized helium
Old exam 1: The loss of an electron from a neutral helium atom results in...?
Upper to lower
Old exam 1: When an atom absorbs a photon containing energy, any of the following can happen except an electron moving from a(n) ... energy to a(n) ... one. Upper to lower or Lower to Upper?
Its is forbidden
Old exam 1: In those stupid line figure things that show the stupid arrows going up or down levels can one of the stupid arrows go a partial line? Why or why not?
the energy structure of the atoms of that element is unique
Old exam 1: Why do atoms of different elements have different spectral line structures from each other?
towards earth
Old exam 1: Which direction does a star need to be moving (relative to earth) to create a blue shift?
towards us
Old exam 1: from laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers. The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can you conclude? Is the star is moving away or towards us...?
visible light and radio waves
Old exam 1: Which two wavelengths regions of the electromagnetic spectrum entirely penetrate Earth's atmosphere and reach the surface?
Nuclear fusion
Old exam 2: A star's life is a struggle between ... wanting to crush it, and ... wanting to expand it?
Old exam 2: Which stellar parameter can be best determined by observations of binary stars?
Old exam 2: In addition, if the binary system is eclipsing, this other stellar parameter can be determined for both stars?
they would generate so much power that they would blow away a great amount of their mass
Old exam 2: No stars have been found with masses greater than about 120 times the mass of our Sun because..
Examining the patterns of the absorption lines from various neutral and ionized atoms in a stellar spectrum. These patterns are related to the temperature of the star
Old exam 2: Spectral classification of stars in the lettered categories OBAFGKM is carried out by..?
main sequence stage
Old exam 2: When a star is fusing hydrogen into helium in the core?
radial velocity
Old exam 2: The H-R diagram is a very useful tool in astronomy because by plotting hte luminosity vs. the temperature of hundreds of stars, other stellar properties can be inferred. Which property cannot be inferred from the diagram?
radial velocity
main sequence lifetime
evolutionary stage
Its initial mass
Old exam 2: Which property determines the evolutionary of a star?
Star y
Old exam 2: If star x has a luminosity of 10,000 and a temperature of 5,000K and star y has a luminosity of .001 and a temperature of 5,000K which one is larger
2 arcseconds
Old exam 2: From a distance of 1 parsec, the angular size of Earth's orbit is...?
Rigil Kentaurus
Old exam 2: Parallax angles are given in arcseconds for the 5 brightest stars. Which star is closest to us?
Sirius: 0.379
Canopus: 0.010
Rigil Kentaurus: 0.742
Arcturus: 0.054
Vega: 0.129
100 parsecs
Old exam 2: The distance of Canopus in parsecs is...? (.010")
Old exam 2: From the blackbody curve of the star, using the wavelength that corresponds to the maximum intensity you can determine the ... of a star?
Old exam 2: From the spectral lines you can determine the .... of a star?
Old exam 2: The star's ... is the total amount of light that the star radiates each second?
Nothing because the mass at the center remains unchanged
Old exam 2: If the Sun could be instantaneously replaced by a white dwarf with mass equal to the mass of the sun, what would happen to the orbits of the planets?
Enif is cooler than the Sun
Old exam 2: The spectral type of the star Enif is K2, while that of the Sun is G2. Which conclusion can be drawn from this information?
73% Hydrogen, 25% helium, 2% other elements
Old exam 2: The composition of almost all stars, but mass, is approximately?
White dwarf?
Old exam 2: The remains of a star that no longer produces energy by nuclear fusion?
Huge, cool dust and gas clouds
Old exam 2: New stars are formed by...?
Old exam 2: The MORE massive stars have SHORTER lifetimes than less massive stars because the higher temperatures in the cores of more massive stars ... the rate of thermonuclear reactions... Increase or decrease?
Red giant, planetary nebula, white dwarf
Old exam 2: After the Sun leaves the main sequence, it will follow this evolutionary path?
4.6 billion years
Old exam 2: The sun has been in its main sequence for...?
When the hydrogen fuel in its core is used up
Old exam 2: When does a star leave the main sequence?
Very dim and very hot
Old exam 2: Which of the following corresponds to the position of a white dwarf on the H-R diagram?
Old exam 2: Who measured the circumference of the earth in 3rd century BC by noticing that on the summer solstice, a vertical stick cast no shadow on Syene. But at the same time, a vertical stick in Alexandria indicated that the Sun is 7 degrees from the zenith?
They are at their minimum distance form Earth
Old exam 2: What did Ptolemy's model predict about the distance to Mars, Jupiter and Saturn when in retrograde motion?
Copernicus' model predicted planetary positions much more accurately
Old exam 2: Out of copernicus's model and Ptolemaic, which predicted more accurately?
Phases of Venus
Old exam 2: Which of Galileo's observations was in direct contradiction to the Ptolemaic system?
36 times the present value
Old exam 2: The universal law of gravitation is an inverse square law. This means that if Earth were 1/6 its current distance from the Sun, the force between them would be...?
Old exam 2: earth orbit is what shape...?
Tycho Brahe
Old exam 2: Which asshole measured planetary positions very accurately, which Kepler later used to find the shapes of planetary orbit?
faster near perihelion
Old exam 2: Kepler's 2nd law says that "a line joining a planet and the Sun sweeps out equal areas in equal times." This means that a planet moves...?
fastest orbit
Old exam 2: From Keplar's third law, the satellite with the lowest orbit has the...?
it doesn't
Old exam 2: Keplar's third law relates the orbital period of a planet around the Sun with the semimajor axis of its orbit. According to this law how does a planet's mass affect its orbital period?
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