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WorksheetsStellar & Galactic Astronomy
Total questions: 126
Worksheet time: 1hrs 3mins
In which type of galaxy are type II supernovae most likely to occur?
Spirals
Ellipticals
In which type of galaxy are type Ia supernovae most likely to occur?
Spirals
Ellipticals
Type Ia spectrum vs type II. What differences can you tell?
Type Ia lacks hydrogen lines, while Type II shows strong hydrogen lines.
Type Ia shows strong hydrogen lines, while Type II lacks them.
Both Type Ia and Type II lack hydrogen lines.
Type II shows no spectral lines at all.
According to the color-coded box: Blue is new, Red is dead, Blue is hot, Red is not. What does 'Red is dead' mean in the context of stellar astronomy?
Red stars are old and have exhausted their fuel.
Red stars are newly formed and very hot.
Red stars are in the process of becoming blue stars.
Red stars are the youngest and most active stars.
What type of supernova does not have any hydrogen lines and is mainly made of carbon when it died?
Type Ia
Type II
Type Ib
Type Ic
Which of the following is NOT a pro of the Supernova Method?
Extremely luminous -> measures extremely large distances
Type Ia are relatively simple to model and measure
Type Ia can be used for spirals and ellipticals
Random, can’t predict when one will go off
List one con of the Supernova Method for measuring distances in astronomy.
Random, can’t predict when one will go off OR Need a light curve, worse measurement if whole thing isn’t observed OR Don’t last long (~few weeks - months), hard to observe quick events
Supernovae are always visible in the night sky
Supernovae provide the most accurate distance measurements without any limitations
Supernovae can only be observed with the naked eye
Who were the two scientists involved in the Great Debate about the scale of the Milky Way and Universe?
Edwin Hubble and Albert Einstein
Harlow Shapley and Herber Curtis
Carl Sagan and Vera Rubin
Isaac Newton and Galileo Galilei
According to Shapley’s Argument, the Milky Way is the entire universe.
True
False
According to Curtis’ Argument, spiral nebulae are 'island universes'.
True
False
In 1924, who observed Cepheids in Andromeda and used Leavitt’s Law to measure Andromeda’s distance?
Hubble
Einstein
Shapley
Eddington
What is the current measurement of the distance to Andromeda?
2.3 Mly
0.5 Mly
10 Mly
100 kly
Redshift occurs as something emitting light moves away, causing the wavelength to stretch out. What color does this correspond to?
Redder color
Bluer color
Green color
Yellow color
Blueshift occurs as something emitting light moves toward you, causing the wavelength to compress. What color does this correspond to?
Bluer color
Redder color
Greenish color
Yellowish color
According to the color key, what does blue represent?
Blue is new
Blue is dead
Blue is hot
Blue is not
What does the expansion of the universe mean?
The universe is expanding.
The universe is shrinking.
The universe is staying the same size.
The universe is spinning faster.
What do spectra of farther galaxies reveal about the emission/absorption lines?
The emission/absorption lines are redshifted.
The emission/absorption lines are blueshifted.
The emission/absorption lines disappear completely.
The emission/absorption lines become broader but do not shift.
Each line is shifted to a longer wavelength. What does the amount of shift determine?
The amount of shift determines its velocity.
The amount of shift determines its temperature.
The amount of shift determines its brightness.
The amount of shift determines its size.
What is the slope of the line in the redshift-distance relationship?
The expansion rate of the universe, H₀.
The mass of the universe, M₀.
The age of the universe, t₀.
The temperature of the universe, T₀.
What is Hubble's Law formula for velocity?
V = H₀D
V = D/H₀
V = H₀/V
V = D × V
What is the current value of H₀?
~70 km/s/Mpc
~10 km/s/Mpc
~300 km/s/Mpc
~1500 km/s/Mpc
If H₀ = 70 km/s/Mpc and a galaxy's velocity is 1400 km/s, how far is the galaxy?
20 Mpc
10 Mpc
50 Mpc
100 Mpc
The rate of expansion is observed to be the same everywhere.
True
False
The Universe is like the surface of an expanding balloon. What does this analogy imply about the universe's center or edge?
There is no center or edge, and every dot sees all other dots moving away.
There is a fixed center at the middle of the balloon.
The edge of the balloon represents the edge of the universe.
The analogy implies the universe is flat and has boundaries.
What is the Cosmological Principle?
On a large enough scale, the Universe is the same regardless of the location. On large scales, matter is evenly distributed without a center or edge.
The Universe is expanding at an accelerating rate due to dark energy.
The Universe has a definite center and edge where matter is concentrated.
The laws of physics change depending on the location in the Universe.
What is Lookback Time?
The time between detected light and when it was originally emitted by the source.
The time it takes for a star to form from a nebula.
The time required for a planet to orbit its star once.
The time it takes for light to travel from the Sun to the Earth.
What is the Observable Universe?
All photons which have had time to travel to us — all we’re ever able to observe.
All galaxies that exist in the entire universe.
Only the stars visible to the naked eye from Earth.
The region of space containing only our solar system.
What is Hubble Flow?
The amount of a galaxy’s velocity solely caused by the Universe’s expansion.
The gravitational pull between galaxies.
The rotation speed of a galaxy around its center.
The movement of stars within a galaxy.
Hubble Flow gets stronger (more velocity from expansion) at further distances.
True
False
According to the color key, what does 'Blue is hot' mean?
Blue is hot.
Blue is cold.
Blue is neutral.
Blue is warm.
What does 'Blue is new' mean in the context of stellar astronomy?
Blue stars are older
Blue stars are newly formed
Blue stars are dead
Blue stars are not hot
What does 'Red is dead' mean in the context of stellar astronomy?
Red stars are newly formed
Red stars are dead
Red stars are hot
Red stars are not dead
Blue is _____
hot
cold
sweet
loud
Red is _____.
not (hot)
cold
blue
soft
In the nearby Universe, Hubble Flow isn’t as strong. A nearby galaxy’s velocity is influenced more by gravity. Galaxies move within clusters due to local interactions, and the cluster itself has its own motion (local flow). What is the term for the amount of a galaxy’s velocity caused by local gravitational interaction?
Hubble Velocity
Peculiar Velocity
Cosmic Microwave Background
Recessional Velocity
For nearby galaxies, the velocity (V) is given by the equation V = H₀D ± Vₚₑc. What does Vₚₑc represent?
The amount of a galaxy’s velocity caused by local gravitational interaction (Peculiar Velocity).
The total mass of the galaxy.
The distance from the galaxy to Earth.
The rate of star formation in the galaxy.
Most measurements of H₀ come from using the best results from the distance ladder.
True
False
The Planck satellite predicts H₀ = ____ km/s/Mpc.
67.4
73.2
70.0
65.0
Supermassive Black holes (SMBHs) are black holes with masses approximately how many times the mass of the Sun?
10^6 – 109 times the mass of the Sun
102 – 104 times the mass of the Sun
1010 – 1012 times the mass of the Sun
10^3 – 10^5 times the mass of the Sun
SMBHs are (roughly) broken into two types. 1) ________: a SMBH with matter orbiting around it, but not falling into it 2) ________: a SMBH with matter orbiting around it and falling into it
Quiescent 2) Active
Dormant 2) Energetic
Passive 2) Accreting
Silent 2) Consuming
Which galaxy's center was observed using orbits of stars to prove the existence of a SMBH (Sagittarius A*) with a mass of 4,000,000 times the Sun’s mass?
Milky Way
Andromeda
Triangulum
Whirlpool
Which Nobel Prize did the discovery of Sagittarius A* win in 2020?
Nobel Prize in Physics
Nobel Prize in Chemistry
Nobel Prize in Literature
Nobel Peace Prize
What do we observe for active and quiescent SMBHs to study their properties?
Disks of gas or groups of stars orbiting close to the black hole
Jets of water flowing from the black hole
Rings of planets forming around the black hole
Clouds of dust far away from the black hole
What does more shifting in the spectroscopy of gas or stars near a SMBH indicate?
More massive SMBH
Lower temperature of the gas
Presence of planetary rings
Less luminous stars
The image of Messier 87’s SMBH taken by the Event Horizon Telescope (EHT) in 2019 is important because:
It is the only real image of a black hole we have
It was taken by a single telescope
It shows the accretion disk in infrared
It was taken in 2020
What is an accretion disk?
Disk of material being eaten by a SMBH
A ring of stars orbiting a planet
A belt of asteroids between Mars and Jupiter
A layer of gas surrounding Earth's atmosphere
What is a jet in the context of SMBHs?
Outflowing, superheated material from the accretion disk moving near the speed of light
A region of low density surrounding the black hole
A type of star orbiting the black hole
A cloud of cold gas falling into the black hole
For the two different AGN spectra shown, what do you notice?
The two AGN spectra have different emission lines and continuum shapes.
Both AGN spectra are identical in every feature.
The AGN spectra show no emission lines at all.
Both AGN spectra have the same continuum but different emission lines.
What does the AGN Unified Model state about AGNs?
AGNs have different designs
AGNs all have the same design, just viewed from different angles
AGNs are only visible in infrared
AGNs do not have emission lines
What is the region of thick clouds and dust that surrounds the equator of the AGN called?
Broad Line Region (BLR)
Torus
Narrow Line Region (NLR)
Seyfert
The ___ is a region of clouds close to the SMBH whose emission lines are broadened (redshift + blueshift) from extremely fast rotation.
Broad Line Region (BLR)
Narrow Line Region (NLR)
Accretion Disk
Event Horizon
Which region of clouds is further from the SMBH and has emission lines not affected by rotation?
Broad Line Region (BLR)
Torus
Narrow Line Region (NLR)
Quasar
Seyfert 1 AGN shows which type of emission lines?
Only narrow emission lines
Only broad emission lines
Both broad and narrow emission lines
No emission lines
Seyfert 2 AGN only displays narrow emission lines because the BLR is blocked by the torus.
True
False
What does SMBH stand for in astronomy?
Supermassive Black Hole
Solar Magnetic Binary Halo
Stellar Mass Binary Helix
Sub-Molecular Black Hole
What is the purpose of reverberation mapping in SMBH mass measurements?
To measure the temperature of the AGN
To measure the rotation of the BLR from broadened spectra
To measure the size of the torus
To measure the brightness of the quasar
Quasar is a quasi-stellar object and a high-z version of AGNs.
True
False
Blazar is a quasar with its jet aimed nearly exactly toward the observer (us).
True
False
Recent studies show that black holes correlate with their entire galaxy's stellar mass.
True
False
The early universe was extremely hot and dense. As it expanded, it cooled down drastically until reaching approximately ___ Kelvin (~ -450 Fahrenheit) today.
2 Kelvin
273 Kelvin
100 Kelvin
0 Kelvin
Which of the 4 fundamental forces keeps you from sinking through the Earth?
Strong force
Weak force
Electromagnetism
Gravity
The strong force holds _______ together.
atomic nuclei
electrons and protons
molecules
planets
The weak force is responsible for ________, i.e. neutrons decaying into protons, electrons decaying into neutrinos.
decay
fusion
fission
ionization
Electromagnetism is the interaction between ________ particles (repulsion or attraction).
charged
neutral
magnetic
atomic
Gravity is the attraction force due to ________, or the bending of spacetime due to mass.
mass
energy
temperature
pressure
Which of the following is NOT one of the four fundamental forces of the universe?
Strong force
Weak force
Electromagnetism
Friction
Gravity
The photons released at the start of the Atoms Era is what we detected as the ________ (CMB).
Cosmic Microwave Background
Cosmic Radio Burst
Gamma Ray Flash
Solar Wind Background
Expansion of the Universe has redshifted those λs to microwave, hence cosmic ________ background.
MICROWAVE
INFRARED
ULTRAVIOLET
RADIO
We have directly detected the leftover radiation from the Big Bang, known as the ________.
CMB (Cosmic Microwave Background)
Solar Wind
Gamma Ray Burst
Aurora Borealis
According to the Big Bang Theory, what percentage of the Universe consists of Hydrogen (H)?
~75%
~25%
~50%
~90%
According to the Big Bang Theory, what percentage of the Universe consists of Helium (He)?
~25%
~50%
~10%
~75%
The Big Bang Theory correctly predicts the abundance of which elements?
He and other light elements
Heavy metals like gold and uranium
Transition metals like iron and nickel
Rare earth elements like neodymium and europium
What does the color code indicate?
Blue is new, Red is dead
Blue is cold, Red is bold
Blue is old, Red is gold
Blue is hot, Red is not
What is the period of exponential expansion of the Universe from ~10^{-36} to 10^{-32} seconds after the Big Bang called?
Inflation
Expansion
Contraction
Equilibrium
How many possible geometries does the Universe have according to the Big Bang Theory?
2
3
4
5
What percentage of the Universe is baryonic matter (stars+gas)?
~5%
~25%
~50%
~70%
What percentage of the Universe is dark energy?
73%
50%
27%
10%
What percentage of the Universe is dark matter?
~22%
~5%
~50%
~70%
During what era of the early Universe were photons finally released?
Atoms Era
Quark Era
Inflation Era
Nucleosynthesis Era
Which of the following galaxy characteristics has not been observed to correlate with others?
None of the above
Luminosity
Mass
Color
Which rung of the distance ladder did Hubble use to prove Andromeda was its own galaxy separate from the Milky Way?
Leavitt's Law
Tully-Fisher relation
Type Ia supernovae
Parallax
Which of the following is not one of the 4 fundamental forces of the Universe?
Hydrostatic Force
Gravitational Force
Electromagnetic Force
Weak Nuclear Force
Dark energy comprises approximately % of the Universe.
75
25
50
90
In which type of galaxy are type Ia supernovae most likely to occur?
Spirals and Ellipticals
Irregulars
Dwarf Spheroidals
Lenticulars
What is the observable Universe?
All photons which have had time to travel to us.
All the stars in the Milky Way galaxy.
Everything that exists in the entire Universe.
Only the planets visible to the naked eye.
Which of the following is a possible conclusion from the disagreement between values of H0?
Something is possibly wrong with our models of the Universe
There is possibly new physics to understand about the Universe
Something is possibly wrong with our methods of observation.
The supermassive black hole at the center of Messier 87 is larger than our Solar System.
True
False
A Type Ia supernova is the explosion of the outer layers of a massive star after core collapse.
True
False
The broad line region can be observed for face-on and edge-on AGN.
True
False
On large scales, the distribution of matter in the Universe is even without a center or edge.
True
False
We have directly imaged both Sagittarius A* and the supermassive black hole at the center of Messier 87.
True
False
Hubble Flow gets weaker for galaxies at further distances, while gravitational interactions get stronger.
True
False
As you move backwards in the Universe's timeline, the strength of gravity increases.
True
False
The present-day Universe has a closed geometry.
True
False
Supernova explosions can shine as bright as an entire galaxy for weeks to months.
True
False
From every galaxy's perspective, nearly every galaxy in the Universe is moving away from them.
True
False
Which of the following best describes Hubble Flow, peculiar velocity, and the reason why distances calculated using Hubble's Law can be inaccurate?
Hubble Flow is the general expansion of the universe, peculiar velocity is the individual motion of galaxies, and distances from Hubble's Law can be inaccurate due to these individual motions.
Hubble Flow is the motion of planets in the solar system, peculiar velocity is the speed of light, and Hubble's Law is always accurate.
Hubble Flow is the rotation of galaxies, peculiar velocity is the expansion of the universe, and Hubble's Law is never used for distance calculations.
Hubble Flow is the movement of stars within a galaxy, peculiar velocity is the gravitational pull between galaxies, and Hubble's Law is inaccurate due to measurement errors only.
Consider the image of the supermassive black hole hosted by Messier 87 below. Which of the following best describes the image, including what the illuminated portion is, how it behaves, why the bottom is brighter than the top, why we observe the black hole and its "shadow," and whether lensing effects are observed?
The illuminated portion is the accretion disk, which orbits the black hole; the bottom is brighter due to relativistic beaming; we observe the black hole's shadow due to gravitational lensing, which is present in the image.
The illuminated portion is the event horizon, which emits light; the top is brighter due to Doppler effect; we observe the black hole's shadow due to magnetic fields, with no lensing effects.
The illuminated portion is the black hole itself, which glows; the brightness is uniform; we observe the shadow due to dust clouds, and lensing is not observed.
The illuminated portion is a foreground star; the brightness varies randomly; the shadow is an artifact, and lensing is not involved.
Briefly describe the 4 methods of supermassive black hole mass measurement and what types of/specific supermassive black holes each method can be applied to.
The 4 methods are stellar dynamics, gas dynamics, reverberation mapping, and megamaser observations, each applicable to different types of supermassive black holes.
The 4 methods are gravitational lensing, X-ray emission, radio bursts, and cosmic microwave background analysis, all applicable to any black hole.
The 4 methods are only theoretical and cannot be applied to any real supermassive black holes.
The 4 methods are time dilation, redshift, Hawking radiation, and gravitational waves, used for all black holes.
Which of the following best describes the pros and cons of the supernova method for black hole measurement?
It allows measurement of black holes formed from supernovae but is limited by the rarity and unpredictability of such events.
It is the most accurate method for all black holes and has no significant limitations.
It can only measure black holes in binary systems and is not affected by supernova rarity.
It is useful for measuring supermassive black holes but not stellar-mass black holes.
Briefly describe the Big Bang Theory, specifically addressing the following: a. Approximately how long ago did the "Bang" occur?
~14 billion years
~4.5 billion years
~100 million years
~100 billion years
Briefly describe the Big Bang Theory, specifically addressing the following: b. What is inflation and how does it relate the Cosmic Microwave Background to the present day Universe?
Rapid expansion, took fluctuations in CMB to large scale mass distribution
Gradual cooling, caused stars to form instantly
Sudden contraction, led to disappearance of CMB
Slow expansion, had no effect on mass distribution
Briefly describe the Big Bang Theory, specifically addressing the following: c. What is the geometry of the present-day Universe?
Slightly open
Perfectly flat
Completely closed
Irregular and undefined
Briefly describe the Big Bang Theory, specifically addressing the following: d. Approximately what percentages of the Universe are comprised of baryonic matter, dark matter, and dark energy?
~5% baryonic, ~20% dark matter, ~75% dark energy
~10% baryonic, ~30% dark matter, ~60% dark energy
~25% baryonic, ~50% dark matter, ~25% dark energy
~70% baryonic, ~20% dark matter, ~10% dark energy
Type II supernovae are easier distance indicators than Type Ia supernovae
True
False
Using the cosmic distance ladder, we have observed the Universe to be
accelerating in its expansion
spirals & ellipticals
false
In which type of galaxy are type Ia supernovae most likely to occur?
accelerating in its expansion
spirals & ellipticals
false
Hubble Flow gets weaker for galaxies at further distances while gravitational interactions get stronger.
accelerating in its expansion
spirals & ellipticals
false
The young Universe was uniform, thus providing the blueprint for the Cosmological Principle
accelerating in its expansion
spirals & ellipticals
false
Which rung of the distance ladder did Hubble use to prove Andromeda was its own galaxy separate from the Milky Way?
Leavitt's Law
Type Ia light curves all have the same inherent shape
true
the contribution of a galaxy's velocity from gravitational interaction
Why are Type Ia supernovae standard candles?
Leavitt's Law
Type Ia light curves all have the same inherent shape
true
the contribution of a galaxy's velocity from gravitational interaction
From every galaxy's perspective, nearly every galaxy in the Universe is moving away from them.
Leavitt's Law
Type Ia light curves all have the same inherent shape
true
the contribution of a galaxy's velocity from gravitational interaction
peculiar velocity is
Leavitt's Law
Type Ia light curves all have the same inherent shape
true
the contribution of a galaxy's velocity from gravitational interaction
What causes the broadening of emission lines observed in some AGNs?
High rotation speeds of gas near the SMBH
bonding of atomic nuclei
white dwarf
false
True
the strong force is responsible for
High rotation speeds of gas near the SMBH
bonding of atomic nuclei
white dwarf
false
True
A Type Ia supernova is the detonation of a
High rotation speeds of gas near the SMBH
bonding of atomic nuclei
white dwarf
false
True
The present-day Universe has a closed geometry.
High rotation speeds of gas near the SMBH
bonding of atomic nuclei
white dwarf
false
True
Nearly every major galaxy in the observable Universe has a SMBH at its center.
High rotation speeds of gas near the SMBH
bonding of atomic nuclei
white dwarf
false
True
As you move backwards in the Universe's timeline, the strength of gravity increases.
True
False
Photons were released into the Universe at the start of the Particle Era
True
False
- On large scales, the distribution of matter in the Universe is even without a center or edge.
True
False
what is critical density?
the density at which a black hole becomes supermassive
The density at which the Universe expands forever
The density at which the expansion of the Universe is halted
The density at which the Universe collapses into a black hole
Quasars are high-z versions of AGNs
True
False
Closed
critical; expansion will halt and reverse
critical; Universe will expand forever
critical; expansion is halted, does not expand nor contract
Open
critical; expansion will halt and reverse
critical; Universe will expand forever
critical; expansion is halted, does not expand nor contract
Flat
critical; expansion will halt and reverse
critical; Universe will expand forever
critical; expansion is halted, does not expand nor contract
