Final (Comprehensive) Flashcards
What is our cosmic address?
Earth, solar system, Milky Way Galaxy, local group, local supercluster, Universe
The start of the Universe’s expansion is commonly called ___ ___ ____.
The Big Bang
The farther away we look in the ____, the farther back we look in ____.
distance; time
Lightyears
The distance light can travel in one year
According to the Voyage Model, if the Sun was a grapefruit, the Earth would be a ____ ______. Jupiter would be a _____.
pen’s ballpoint; marble
The nearest star to the Sun is __ light years away.
4
If a light year is 1 mm, the Milky Way is the length of a _____ _____.
football field
If the time span between the Big Bang and now were a calendar, when would humans be?
Last 30 seconds of December 31
Earth’s daily rotation is…
how it spins on its axis
Earth’s orbit around the Sun is a _____.
revolution
Earth’s average orbital distance is equal to
1 au (astronomical unit)
1 au =
150 million km
Earth’s orbital path defines a flat plane called an ____ ____.
ecliptic plane
Does the solar system move in relation to other stars?
Yes
How fast does the solar system move in relation to other stars?
70,000 km per hour40,000 mph
Virtually, every galaxy outside the Local Group is moving ____ us.
away from
Who developed the first scientific model for astronomy?
Ancient Greeks
All scientific models are subject to being _____.
disproved
Always change the ____ rather than the ____.
model; data
A scientific model requires what 3 things?
Geometry, Physics, Aesthetics
What are the 5 steps of a scientific model?
“Real World” -> observe nature -> Model (geometry, physics, aesthetics) -> comparative observations -> revise model to match observations
Does a scientific model require accuracy to qualify as a model?
No
What type of universe did Ptolemy believe in?
Ptolemaic System: geocentric
Did the Ptolemaic System qualify as a scientific model? Was it accurate?
Yes; No
uniform circular motion
Move in a circle at a non-varying speed
Aristotelian Physics
The natural motion of all earthy materials is to fall towards the center of the universe (Earth)
What are the four earthy materials in Aristotelian Physics?
Earth, air, fire, water
According to Aristotelian Physics, what are the planets/heavenly bodies made of?
The 5th material, quintessence
Greeks were obsessed with perfect _____ and _____.
circles; spheres
What three things supported the Ptolemaic System?
uniform circular motion, Aristotelian Physics, Greek love of perfect circles and spheres
Greeks believed the heavenly bodies had no ____.
blemishes
Copernicus proposed a ____ model for the universe.
heliocentric
What did Copernicus believe orbited the earth?
Just the moon
What was the Copernican System’s primary motivation?
Aesthetics
Was the Copernican System more accurate than the Ptolemaic System? Why or why not?
No. Held flawed belief in uniform circular motion.
Did the Copernican System qualify as a scientific model?
No, there was no physics aspect.
What was the geometry aspect of the Copernican System?
uniform circular motion
Was the Copernican System a better or worse scientific model than the Ptolemaic System?
worse
What did Tycho Brahe contribute to astronomy?
astonishingly accurate naked-eye observations
How were Tycho’s observations so accurate?
he had a giant angle-measurer
How accurate were Tycho’s observations?
within an arcminute
What is an arcminute?
1/60 of a degree
Did Tycho side with Ptolemy or Copernicus?
Ptolemy
Tycho’s data allowed people to _______________.
test the Ptolemaic and Copernican models
What did Galileo contribute to astronomy?
he invented a stronger telescope
Galileo began the process of finding _____ to satisfy the Copernican System.
physics
What made Kepler a better scientist than those before him?
He tossed out ideas if they didn’t fit the model or agree with the data.
Kepler tossed out ideas if they didn’t fit the ____ or agree with the ____.
model; data
Kepler was _____’s apprentice.
Tycho
Did Kepler like the Ptolemaic or Copernican System?
Copernican
What did Kepler discover?
elliptical orbits
Kepler changed the ____ to fit the ____.
model; data
What is an example of Kepler changing the model to fit the data?
He substituted an ellipse for a circle in regards to orbits.
What is Kepler’s first Law of Planetary Motion?
Planets orbit the Sun in elliptical orbits with the sun at one focus.
What is Kepler’s second Law of Planetary Motion?
As a planet orbits the Sun, its distance from the Sun changes. If it’s closer to the Sun, it moves faster. If it’s farther from the Sun, it moves slower.
According to Kepler’s second law, planets move faster when they are _____ ____ the Sun.
closer to
According to Kepler’s second law, planets move slower when they are _____ ____ the Sun.
farther from
What is Kepler’s third Law of Planetary Motion?
There is a mathematical relation between a planet’s period (time it takes to orbit Sun) and its distance from the Sun.p^2 = K * a^3More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationshipp^2 = a^3
In p^2 = K * a^3, what is p?
p = period
In p^2 = K * a^3, what is K?
K involves the mass of the Sunwith right units, K = 1, rendering it unnecessary in the equationp^2 = a^3
In p^2 = K * a^3, what is a?
a = distance between the Sun and the planetmeasured in au (astronomical units)
p^2 = K * a^3 can be used to determine the ____ of stars.
mass
Kepler’s third law is the only way we have of measuring the ____ of faraway space objects.
mass
How did Kepler’s model involve physics?
magnetic force between Sun and planets (incorrect)
How did Kepler’s model involve geometry?
ellipses
Isaac Newton built on _____’s model and _____’s data.
Kepler; Galileo
What does Newtonian Physics include?
Three Laws of Motion and Law of Gravity
Newton’s telescopes used ____ instead of lenses.
mirrors
Newton invented what mathematical discipline?
calculus
Newton’s Three Laws of Motion ____ (prove/disprove) Kepler’s Laws.
prove
Newton’s Laws explain the movement of ____.
planets or heavenly bodies
What is Newton’s first law?
Inertia. Every body continues in its state of rest or uniform motion in a straight line unless an external force acts. An object at rest tends to stay at rest, while an object in motion tends to stay in motion.
Velocity includes ____ while speed does not.
direction
acceleration
any change in velocity (speeding up, slowing down, changing direction)
A negative acceleration is _____ ____.
slowing down
A positive acceleration is ____ ____.
speeding up
G-force happens when you’re in something accelerating ____.
positively
Inertia happens when you’re in something accelerating ____.
negatively
What is the difference between G-force and inertia?
G-force: positive accelerationInertia: negative acceleration
In order to accelerate an object, you must apply __ _____ ____.
an external force
Applying a perpendicular external force to an object changes ____.
velocity
Applying a parallel external force to an object changes ____.
speed
To change an object’s velocity, you must apply a _____ _____ force.
perpendicular external
To change an object’s speed, you must apply a _____ _____ force.
parallel external
When applying the same force, more massive objects accelerate ____ and less massive objects accelerate ____.
less; more
What is Newton’s second law?
force = m*aforce = mass * acceleration
The rate of change of momentum of a body is proportional to ____ ______ ______.
the applied force
The rate of change of momentum of a body takes place in the direction ___ _____ _____.
the forces takes
What is Newton’s third law?
To every action, there is an equal and opposite reaction.
What is the reaction of Earth’s gravity pulling you down toward its center?
you pull the Earth up with the same amount of force
What is an example of an action/reaction pair?
you/EarthEarth/Sun
action = ?
action = change of momentum * distance over which momentum is changed
Earth pulls you down and you pull Earth up with a force equal to ____ ____.
your weight
Explain the fuel/rocket action/reaction pair.
The built up fuel pressure pushes out back of rocket, thrusting rocket up.
What is Newton’s Law of Universal Gravitation?
There is a force of gravitation between any 2 objects in the universe. More massive objects have a greater gravitational force.Force = G * [Mass(1) * Mass(2)] / (Distance)^2
_____ is also a factor in Newton’s Law of Universal Gravitation.
Distance
radius
the distance to the center
Give an example of distance being a factor in Newton’s Law of Universal Gravitation.
You -> EarthEarth -> Sun
Where should you measure the distance between two objects from?
their centersex.: Earth’s center -> your bellybutton
In Force = G * [Mass(1) * Mass(2)] / (Distance)^2, what is G?
gravitational constant
In Force = G * [Mass(1) * Mass(2)] / (Distance)^2, what is the distance?
between the two objects’ centers
Why don’t you fall toward other objects if there’s a gravitational force between you?
The gravitational force between you and the Earth is greater, because Earth has a greater mass than any object on it. Earth pulls you down.
If the distance between two objects doubles, there’s ____ the force.
1/4
If the distance between two objects triples, there’s ____ the force.
1/9
If the distance between two objects is 10 times, there’s ____ the force.
1/100
If an object weighs 100 N, and its distance from Earth doubles, what does it weigh now?
25 N (Newts)
The moon is basically ____.
falling
The more massive object has more force acting on it, thus it takes ___ force to accelerate it.
more
Two objects orbiting the same object will have ___ orbital periods/speed/etc.
equal
In general, for anything to move in a circular path, you have to have an inward force that’s constantly applied for a change in direction. What is this force?
centripetal force
centripetal force
a force that acts on a body moving in a circular path and is directed toward the center around which the body is moving
When the moon orbits Earth, ____ applies the centripetal force.
gravity
If centripetal force suddenly stops, the object will…
go in a straight line (Newton’s first law, inertia)
Do things fall on the moon?
yes
What fraction do objects weigh on the moon compared to Earth?
1/6
While falling, an object is ____.
weightless
What two modifications have been made to Newton’s laws?
Quantum Mechanics (atoms do not obey Newton’s laws)Einstein’s Relativity
What is the Law of Conservation of Energy?
total amount of energy in the universe always remains the same
How does the Law of Conservation of Energy work?
different types of energy (gravitational, motion, etc) convert into one another
Does mass affect orbital periods?
No
What affects orbital periods?
orbital distance
eccentricity
amount an ellipse is stretched compared to a circle; circles have zero eccentricity
Why can we use Kepler’s third law to calculate a planet’s average orbital speed?
The law relates a planet’s orbital distance to its orbital time (period).
How did Galileo answer the aesthetic objection to a heliocentric system?
Using his telescope, he proved the existence of sun spots and mountains & valleys on the moon.
stellar parallax
apparent shifting of an object against a background; parallax depends on distance, nearer objects experience greater parallax than more distant objects
What is Occam’s Razor?
the idea that scientists prefer the simpler or more aesthetically pleasing of two otherwise equal models
spectroscopy
the study of the interaction between matter and radiated energy; the measurement of radiation intensity as a function of wavelength
What is light?
wave of something in the electric field and the magnetic field
electric field
makes electric forces work
magnetic field
makes magnetic forces work
Which two scientists worked together to form spectroscopy? What two tools did they use?
Kirkoff - spectroscopeBunsen - Bunsen burner
What did Kirkoff and Bunsen do?
They put various things in a Bunsen burner and watched through a spectroscope.
What two fields oscillate back and forth to make a wave? How so?
magnetic and electriclarge positive > zero > large negative > zero > large positive > zero > large negative > zero…
What color has the longest wavelength?
red
What color has the shortest wavelength?
blue/violet
What are the characteristics of a red wave? (wavelength, frequency, energy)
long wavelength, low frequency, less energy
What are the characteristics of a blue wave? (wavelength, frequency, energy)
short wavelength, high frequency, more energy
frequency
number of times per second that a wave hits youlonger waves hit less often; shorter waves hit more often
Frequency is measured in ____.
Hertz
high frequency = ____ energy
more
low frequency = ____ energy
less
What are the characteristics of radio waves? (wavelength, frequency, energy)
long wavelength, low frequency, less energy
What are the characteristics of gamma waves? (wavelength, frequency, energy)
short wavelength, high frequency, more energy
How much energy do ultraviolet waves produce in relation to other waves?
a lot (hence sunburns), more than infrared but less than gamma rays
In modern astronomy, how much of the electromagnetic spectrum is used?
all
The formation of the three types of spectra are addressed in ____ Rules.
Kirkoff’s
What are the three types of spectra?
continuous, emission/bright line, absorption/dark line
Describe continuous spectra.
like a full rainbow, no discontinuous or stark changes
Describe emission/bright line spectra.
does not emit light; bright, narrow lines of color; opposite of absorption
Describe absorption/dark line spectra.
opposite of emission; looks like a continuous spectrum with lines missing
What is Kirkoff’s first rule? (How is a continuous spectrum produced?)
A continuous spectrum is produced when you have hot solid, hot liquid, or hot compressed gas.ex. incandescent lightbulb; sun’s core
What is Kirkoff’s second rule? (How is an emission line spectrum produced?)
Emission line spectra are produced by hot thin gas. The wavelengths (colors) of the emission lines depend on the chemical compound.ex. Sodium burns yellow.
What is Kirkoff’s third rule? (How is an absorption line spectrum produced?)
You must have a continuous spectrum first passed through a cool (lower temperature than whatever caused the continuous spectrum) thin gas. Wavelengths reflect the composition of the cool thin gas not whatever caused the initial continuous spectrum.
The sun is hotter in its ___ than its ____ ____.
core; outer atmosphere
What is the spectral result of the sun’s core being hotter than its outer atmosphere?
The core is the continuous spectrum source and the outer atmosphere provides a cool thin gas to create an absorption spectrum.
You must have a ____ spectrum before you can have an absorption line spectrum.
continuous
Can you tell what element is involved by the continuous spectrum?
no
Who figured out the structure of the atom?
Neils Bohr
What did Bohr determine about atoms in relation to element identification?
The number of protons in an atom’s nucleus determines the element.
Electrons orbit the ____ at different levels.
nucleus
Can an electron orbit the nucleus between levels?
no
Can an electron jump from one orbital level to another?
yes
To jump from a lower level to a higher level, an electron needs more ____.
energy
Where does an electron obtain the energy needed to jump to higher levels?
the electron absorbs photons of light
What type of spectrum is produced when an electron jumps to a higher level? Why?
absorption line spectrumthe photon/wavelength of light disappears because it was absorbed by the electron
What type of spectrum is produced when an electron jumps down a level? Why?
emission line spectrumWhen it jumps down, it emits a wavelength of light and releases energy.
In what direction is the light from an electron emitted?
randomnot necessarily in the same direction it was absorbed from
Every element has its own unique set of ___ levels.
energy
Each element emits and absorbs a different amount of ___.
energy
The Doppler effect applies to ___ and ____.
sound; light
Doppler effect
higher pitch means it is moving toward you; lower pitch means it is moving away from you
What are the characteristics of a high pitch sound? (frequency, wavelength)
higher frequency, shorter wavelength
What are the characteristics of a low pitch sound? (frequency, wavelength)
lower frequency, longer wavelength
What happens during a blueshift?
whole pattern shifted toward shorter wavelengths
What happens during a redshift?
whole pattern shifted toward longer wavelengths
Closer stars’ spectral patterns are shifted towards ___.
blueThis is not enough to actually affect the color of the star.
Farther stars’ spectral patterns are shifted towards ___.
redThis is not enough to actually affect the color of the star.
Why are telescopes placed on mountaintops?
to be above the atmosphereless light pollution
What are the three function of an astronomer’s telescope?
1- Light gathering power2- Resolving power3- Magnifying power
What is the least important function of a telescope?
magnifying power
What is the most important function of a telescope?
light gathering power
Telescopes: ____ power is not worth it if you do not have good ____ and ____ power.
Magnifying power is not worth it if you do not have good resolving and light gathering power.Before you get a large image, you must first have a quality image.
resolving power
image claritygood- sharpbad- fuzzysecond most important telescope function
light gathering power
allowance to gather or collect light to view faint/faraway objectsmost important telescope function
What determines the magnifying power of a telescope?
focal length or eyepiece
Resolving power is determined by the main ____ or ___.
mirror; lens
If a telescope’s lens is doubled in diameter, you can see things that are ___ as big.
half
Lens diameter is directly related to…
what size objects you can see
If a telescope’s lens diameter is increased more than about 20 inches, the resolving power is determined by ____ _____.
Earth’s atmosphere
How does the Hubble telescope achieve better resolving power?
It is positioned above Earth’s atmosphere.
What is the formula for the area of a circle?
πr^2
Telescopes are like funnels in order to…
collect more light
If you double the diameter, the area increases by ___.
4
The light gathering power of a telescope depends on the….
square of the diameter
Resolving power depends on the ____.
diameter (of the main lens)
The diameter of the main mirror/lens determines the ____ ____ power and the ____ power.
light gathering; resolving
Lenses ____ and mirrors _____.
Lenses refract and mirrors reflect.
Refracting telescopes use ____ lenses.
convex (curves outward, as opposed to concave)
refract
light bends
focal length
distance from lens to focal point (eyepiece)
Formula: magnifying power =
focal length / distance to object
If a lens is heavy, it will…
sag or curve
What are the 2 primary disadvantages of a refracting telescope?
1- Limit to how big you can make them2- Very expensive
What are the 2 types of reflecting telescopes?
Newtonian DesignCassegrain Design
What are the 2 main features of a reflecting telescope?
eyepieceprime focus configuration
What are 2 benefits of a reflecting telescope?
very large telescopeputs astronomer at eyepiece
Describe a Newtonian Design telescope.
low cost, cheap, good qualityhas secondary mirror
Describe a Cassegrain Design telescope.
eyepiece at bottom for ease of use
What is the most common type of large telescope?
Cassegrain Desgin
Describe a Schmidt Cassegrain telescope.
a little more expensive (than Cassegrain), better image quality, correcting lens
What is the structure of a refracting telescope?
Rays from distant point source=======>LENS—(focal length)—>eyepiece (focal point)
Studying the sun helps us understand ____ ___.
other stars
The mass of a star can be determined using what?
Kepler’s 3rd law (as modified by Newton)planets orbiting the star or binary system orbits
Many stars are in ___ orbits.
binary (2 stars orbiting each other)
A star’s energy output depends on ___ and ____.
temperature; distance
What is the formula to determine the surface area of a sphere?
4πr^2
To determine a star’s energy output, you must know…
how bright it appears to be and distance
Luminosity is measured in…
watts (Joules per second)
luminosity
how much energy is put out per second
What is the sun’s energy output?
3.8 * 10^26
A red star is ___ than a blue star.
cooler
A star’s colors tells us its approximate ____.
temperature
Where a star’s brightness peaks (on the color spectrum) is directly related to ___ and nothing else.
temperature
How does the sun get its energy?
nuclear fusion
How hot is the sun?
6000º K
E=mc^2
energy = mass * (speed of light)^2
In Einstein’s E=mc^2, ____ and ____ are interchangeable.
energy; mass
What is the speed of light?
186000 miles per second3 * 10^8 meters per second
nuclear fission
something (such as heavy elements or heavy atoms) splitting and releasing energy
What is the sun’s composition?
98% H and He2% every other element
nuclear fusion
lighter elements combing to make heavier elements
The sun, at its start, had enough H fuel to last ___ years. It has ___ years left.
10 billion; 5 billion
What is the process of the sun’s nuclear fusion?
4 H atoms make 1 He atomthat difference in mass is converted to energy according to E=mc^2High density forces repel protons together
Where do the sun’s nuclear fusion reactions take place?
in the core
What is the purpose of a convection current on the sun?
transfers heat to its surface
Sun: granules
bubbles from convection currents
Sun: corona
very thin gas only visible during solar eclipse
What are the four parts/layers of the sun?
core, photosphere, chromosphere, corona
Who discovered sunspots? When?
Galileo; 1610
sunspots
areas of sun that are a little coolerwhere convection currents are not going or where energy is passing over
Sunspots have very strong ___ fields.
magnetic
Sunspots deflect ___ currents.
convection
Different colored areas of the sun indicate a difference in ___.
temperature
solar flare
brighter regions of the sun
Sunspots and solar flares are directly related to the sun’s ___ field.
magnetic
When sunspots and solar flares are present, the sun is ___.
active
How long is a solar activity cycle?
about 11 years
solar minimum
few sunspots or solar flaresslightly lower luminosity
solar maximum
lots of sunspots or solar flaresslightly higher luminosity
Describe a solar activity cycle.
(1-4 years) solar minimum -> (next 5-11 years) solar maximum -> (next 1-4 years) solar minimum -> (next 5-11 years) solar maximum -> (next 1-4 years) solar minimum…
coronal mass ejections
material flying out of suncould interact with Earth’s magnetic field
What causes the Northern Lights?
coronal mass ejections
The Little Ice Age
1650s - 1680svery few, virtually no sunspotssolar minimum
Medieval Grand Maximum
1000 AD; more sunspots than normal
What causes global warming?
greenhouse effect caused by too much CO2 in the atmosphere
The ___ of the sun can affect Earth’s climate.
luminosity
Is the brightness of a star in a photo related to the size of the star?
nope
For a red star and a blue star to be of equal brightness, the red star must be ___ than the blue star.
bigger
What do absorption lines in a star’s spectrum tell you about the star’s temperature?
nothing
If you know the luminosity and apparent brightness of a star, you can find the ____.
distance
parallax
closer objects appear to move more than faraway objectshelps determine a star’s angular diameter and its distance from Earth
heliocentric parallax
the parallax of a celestial star using two points in the Earth’s orbit around the sun as the baselinehelps determine a star’s angular diameter and its distance from Earth
parsec
an astronomical unit of distance derived by the theoretical annual parallax (or heliocentric parallax) of one arc second, and is found as the inverse of that measured parallax; equal to 3 lightyears
Brightness is measured in _____
magnitude
The sun’s brightness is equal to ___ magnitude.
-27
The brighter the star, the ___ the magnitude.
lower
A 20th magnitude star is ___ than a 1st magnitude star.
fainter
A 1st magnitude star is ___ times as bright as a 2nd magnitude star.
2.5
A 3rd magnitude star is ____ times as faint as a 1st magnitude star.
(2.5)^2 = 6.25
Stars we can see with the naked eye are between ___ and ___ magnitude
1 and 6
mass
number of kilograms
Size is determined using ___ and ___.
diameter and length
If size is bigger, is mass bigger?
not necessarilythe larger object could be hollow or have low density
On an H-R Diagram, where are white dwarfs?
bottom left
On an H-R Diagram, where are red giants and red super giants?
top rightsuper giants above giants
On an H-R Diagram, where is the main sequence?
curvy line from top left to bottom right
On an H-R Diagram, what is the horizontal axis?
temperature or spectral type; highest -> lowest
On an H-R Diagram, what is the vertical axis?
luminosity or absolute visual magnitude;negative numbers (more luminous)^1 (Sun)^positive numbers (less luminous)
How do you determine the luminosity of a star?
with size and temperatureor apparent brightness and distance
How do you determine the mass of a star?
Kepler’s 3rd law; orbits of stars; measured in kilograms; not equal to size
Kepler’s 3rd law
There is a mathematical relation between period (time it takes to orbit sun) and distance from sun (au).p^2 = K * a^3or p^2 = a^3 if K=1p=period; a=distance between sun and planetK involves mass of sun
How do you determine the temperature of a star?
color; spectrumred = coolblue/white/violet = hot
Mass is usually measured in relation to the ____.
SunIf the sun is 1, a star of 10 solar mass is 10 times the mass of the sun.
Absorption lines depend on the ___ ___ of the star.
chemical compostion
The H-R Diagram was created simultaneously and independently by
Hertzsprung (Dutch) & Russell (American)
List the spectral classes of stars in order.
O B A F G K M - R N S
What is the temperature range of the spectral classes?
O is the hottest, S is the coldest
Which spectral class of star as the weakest H absorption lines?
S
Which spectral class of star has the strongest H absorption lines?
A
Is the strength of a star’s H absorption lines related to the amount of H it contains?
no
Who first classified stars by spectra?
Annie Jump Cannon
Who discovered that strong H absorption lines do not mean more H?
Cecilia Payne-Gaposchkin
What do strong H absorption lines depend on?
temperature
O is too ___ to have H absorption lines.
hot
At ____ºK, A is just the right temperature to show H absorption lines.
10,000
Why doesn’t M have H absorption lines?
M doesn’t have enough (heat) energy to bump electrons up to the right level (2) to have H absorption lines.
All stars have the same chemical composition of…
70% H, <30% He, 2% other
The H absorption lines that the spectral classification system is based on result from a ____ effect.
temperature
Every element has its required ____ to produce absorption lines.
temperature
A class stars produce ___ absorption lines.
H
B class stars produce ___ absorption lines.
He
G and K class stars produce ___ absorption lines.
elemental metals
Goldilocks Range
perfect distance from a star to support lifeex. Earth
Absolute Visual Magnitude
luminosity
On an H-R Diagram, a positive number is ____ luminous than a negative number.
less
Where is the sun on the H-R Diagram?
middle of main sequence
Describe a white dwarf.
Hot, low luminosity, small in size (about the size of earth)
Describe a red giant/supergiant.
cool, large in size, high luminosity
How small (solar mass) can a star be and still generate adequate energy?
1/10 the mass of the sunor .1 solar mass
How massive (solar mass) can a star be and remain stable?
100 times the mass of the sunor 100 solar mass
What is the sun’s solar mass?
1
cluster of stars
group of stars related to one another in space
An open cluster is also know as a ____ cluster.
galactic
How old are stars in an open or galactic cluster?
Relatively young
Describe an open/galactic cluster.
Spread out, individual stars are visible, about 100 stars, usually young
How old are stars in a globular cluster?
Rather old (10-12 billion years, around since the formation of the Milky Way)
When were stars in a cluster formed in relation to one another?
About the same time
Describe a globular cluster.
Stars densely packed in center, like a glob, individual stars only visible on the outer edges, about 100000 stars
What holds a globular cluster together?
Gravity
Nebula
Leftover dust after formation of stars
What does the presence of a nebula tell you?
The nearby stars are very young.
Parallax is used to determine a star’s…
angular diameter and distance from Earth.
The ___ massive stars usually leave the main sequence and become red giants first.
most
More massive stars age ____.
faster
The more massive a star is, the ___ its main sequence lifespan will be.
shorter
The less massive a star is, the ___ its main sequence lifespan will be.
longer
Why do more massive stars evolve faster?
They burn through their H fuel faster in order to maintain their high temperatures and high luminosities.
Do more massive or less massive stars have more H fuel?
more massive
A star of 10 solar mass has __ times the H fuel, but it burns it ______ times as fast, because it puts out ______ times as much energy.
A star of 10 solar mass has 10 times the H fuel, but it burns it 10000 times as fast, because it puts out 10000 times as much energy.
What is the coolest layer/part of the sun?
photosphere6000ºK
A star’s temperature is determined using…
color or spectral classification
How many years does the sun have left?
5 billion
Strong H absorption lines mean the star is…
at the optimal temperature to produce H absorption lines.
The Milky Way is a collection of ___#___ stars in a _____ shape.
a few hundred billion stars; pancake
Why can we see a band of milky white clouds as part of the Milky Way?
We’re inside the galaxy’s pancake shape.
What is the closest spiral galaxy to the Milky Way? How far away is it?
Andromeda; 2 million light years
What is the diameter of a typical galaxy?
100,000 light years
How many miles is a light year equal to?
6 trillion
What did William Hershall do?
He was an astronomer who tried to estimate where we are in the galaxy and its size.
How did Hershall attempt to measure the galaxy?
Star counts
What was Hershall’s conclusion?
The Milky Way isn’t very big and we are in the center.
star counts
Count stars to estimate distanceEx. If a galaxy were to measure 10 stars by 1000 stars, it would extend farther to the right.
What did Harlow Shapley do?
He was an astronomer who counted globular clusters (rather than individual stars) to measure the galaxy.
What did Henrietta Levitt do?
She was a Harvard computer in the early 20th century. She discovered that cepheid variable stars have a relationship between luminosity and period.
Cepheid variable stars burn ____ in the core.
Helium
Define period of a variable star.
Time it takes to go bright, faint, then bright again
Luminosity allows us to find ____.
Distance
What did Shapley mistakenly study?
RR Lyrae Stars
What are the 5 parts of the Milky Way galaxy?
Nucleus, dust, gas lanes, disc, halo
Our galaxy used to be ____, but ___ ___ ___ happened.
spherical; Pizza Dough Physics
Where in the galaxy is the Sun located?
About 2/3 of the way between the center and the edge
How do we know how many stars are in the Milky Way?
Measure speed and orbital period.1- Use Kepler’s Laws2- Assume Sun is average massFormula: Mass of galaxy divided by mass of Sun
The galaxy is ____ massive than we thought.
more
Recent evidence suggests the Milky Way is a ____ spiral galaxy.
barred
How do we know the Milky Way has a spiral arm structure?
using H emitted radio waves, astronomers mapped it out
Which goes through dust easier: optical light or radio waves?
Radio waves
Spiral arms emit ____.
radio waves
Space between stars is filled with ___.
Hydrogen
What is the length of a radio wave emitted by H?
21 cm
H atoms in the ___ ___ of the galaxy emit ___ ___.
spiral arms; radio waves
Where does the Spiral Density Wave come from?
Center of Milky Way
What is the Spiral Density Wave’s pattern?
Compressed, spread out, compressed, etc.
What is Sagittarius A?
First radio source discovered in Sagittarius constellation
Sagittarius A is very ____.
bright
What is Sagittarius B?
Second radio source discovered in Sagittarius constellation
What drives the Spiral Density Wave?
No one knows
Why do we get radio waves coming from the center of the galaxy?
Magnetic field; Synchrotron Radiation
The most energetic source in the core of the Milky Way is the size of a ____ ____.
solar system
What do we suspect is spinning at the Milky Way’s core?
Super massive black hole
What makes a black hole super massive?
Small black holes merge
Who proved there were other galaxies?
Edwin Hubble
What is Extra-Galactic Astronomy?
Study of astronomy outside of the Milky Way
Edwin Hubble proved that the universe is ____.
expanding
Where did Edwin Hubble make his observations?
Telescope on Mt. Wilson
Who was Hubble’s assistant?
Milton Humison
Who discovered the Andromeda Galaxy? How?
Hubble; He found cepheid variable stars and figured out the period, luminosity, and distance. The distance is longer than the Milky Way’s diameter, proving it’s a galaxy outside of ours.
How far away is Andromeda?
2 million light years
What is the Milky Way’s approximate diameter?
100,000 light years
Hubble classified galaxies based on ____.
appearance
What are Hubble’s 2 broad categories for galaxies?
Elliptical & Spiral
There are ____ and Giant Elliptical galaxies.
dwarf
How many types of Elliptical galaxies are there? How do they vary?
8 (E0-E7). E0 is spherical like a basketball. E7 is elongated like a football.
What are the 2 types if spiral galaxies?
Normal/Ordinary (S or SA) and Barred (SB)
What is an S0 galaxy?
S0 galaxies are an intermediate type of galaxy between E7 and a “true” spiral Sa. They differ from ellipticals because they have a bulge and a thin disk, but are different from Sa because they have no spiral structure. S0 galaxies are also known as Lenticular galaxies.
What are the 3 components of a spiral galaxy?
Nucleus, disc, halo
Describe an Sa galaxy.
Spirals compressed, tightly wound around nucleus
Describe an S0 galaxy.
Disc with no spirals
Describe an Sc galaxy.
Spirals spread out, loosely wound
An Sb galaxy is characteristically between ___ and ___.
Sa, Sc
Galactic Cannibalism
how galaxies accrete mass; merging with other galaxies
Hubble’s Classes: Irregulars
galaxies that don’t fit any of Hubble’s classes; no shape
Hubble’s Classes: pec
peculiar; a galaxy that doesn’t perfectly fit a class
What are the 6 main properties of galaxies?
diameter, mass, luminosity, color, percentage of gas content, types of stars
How does a Giant Elliptical galaxy compare to the Milky Way?
bigger, brighter, more massive
How does a Dwarf Elliptical galaxy compare to the Milky Way?
smaller, less massive, fainter
What color is a sample of old stars?
Red
Describe the stars in an Irregular Galaxy.
young, blue, high percentage of gas
What color is a sample of young stars?
blue
What type of stars does an Elliptical Galaxy have?
old, red
What type of stars does a Spiral Galaxy, like the Milky Way, have?
mix of old and new, mix of red and blue
Elliptical Galaxies tend to be ___ with ___ gas content. They ___(are/ are not)___ forming new stars and appear ___ in color.
Elliptical Galaxies tend to be old with very little gas content. They are not forming new stars and appear red in color.
A cepheid variable star is a ___ indicator, sometimes called a ___.
distance; candle
The further away a galaxy is, the ___ it appears to be moving away from us.
faster
The Sun and similar stars can produce an HNK spectral line from ____.
Calcium
When did Hubble discover the universe was expanding?
1930s
What other scientist predicted the universe’s expansion before Hubble? Why isn’t he credited with the discovery?
Einstein, Theory of General Relativity in 1915; he didn’t believe it, so he altered the data to disprove expansion, he later admitted his mistake
What is the Local Group?
group of spiral galaxies (and some dwarf ellipticals) including the Milky Way, Andromeda, M-33, and others
What is the approximate diameter of our Local Supercluster?
130 million light years
What are the empty spaces between superclusters called?
voids
Active Galaxies use up a lot of ___.
energy
Where is the activity in an Active Galaxy usually located?
nucleus, Active Galactic Nuclei (AGN)
Quasars are a type of ____ ____.
Active Galaxy
Quasars emit huge amounts of ___.
radiowaves
What was the first Quasar discovered named? Where was it discovered?
3C 273; Cambridge
jet
material shot from the center of a galaxy
3C 273 is very ____ when viewed via radio wavelengths and emits huge amounts of ____.
bright; radiowaves
Ordinary stars are bright when viewed via ____ ___.
visible light
What is ‘Quasar’ short for?
Quasi-Stellar Radio Source
Most stars have ____ line spectrum, but 3C 273 has ___ line spectra.
absorption; emission
Why didn’t the emission lines from 3C 273 match any known element?
It was H with the largest redshift ever observed.
Why did H in 3C 273 have such a large redshift?
3C 273 is moving away very fast and is located very far away
What are the 8 characteristics of Quasars?
1- emit large amounts of radiowaves2- very bright when observed through radio wavelengths3- emission line spectrum4- emission lines for H with the largest redshift ever observed5- farthest objects in the universe6- moving away from us very fast7- incredibly luminous and energetic8- vary in brightness significantly on various timescales
About how far away is a Quasar?
3 - 5 billion light years
Quasars are the most ____ and ___ things in the universe.
luminous; energetic
The energy output of a typical Quasar is comparable to ____ supernovas.
10,000
3C 273 varies in brightness on a timescale of approximately a few ___.
months
3C 273 is a ___(tame/wild)___ Quasar.
tame
What is the max size of a Quasar like 3C 273?
about a light month
Wilder Quasars will vary in brightness on timescales of about a ___. Their max size is about one light ___.
day; day
Quasars have extremely bright ___.
nuclei
What is the big mystery of Quasars and AGNs?
How do you get so much energy in such a small volume of space?
What is the most reasonable theory for the Quasar/AGN mystery?
Rotating Supermassive Black Holes are at the center. Objects could pick up the black hole’s energy in the ergosphere. The objects are then shot out (like a slingshot), explaining jets.
Galaxies near the Milky Way have settled down and may have ___ ___ ___ ___ in their centers. Why have they settled down?
rotating supermassive black holes; the black hole’s spinning has slowed down over time
If both Quasars/AGNs and regular galaxies have rotating supermassive black holes, what does that mean for Quasars/AGNs?
They will eventually settle down to form regular galaxies as the rotating slows.
What type of galaxy is M-87?
giant elliptical galaxy
M-87 is not a Quasar, but it is very ___. It has a ___ on one side and a ___ on the other, suggesting that the galaxy is orbiting its ___.
M-87 is not a Quasar, but it is very active. It has a redshift on one side and a blueshift on the other, suggesting that the galaxy is orbiting its nucleus.
Astronomers can use orbits like that of M-87 to determine ____.
distance (and other things)
M-87 has helped astronomers assume that galaxies ___ ___ as they get older.
settle down
What are the 2 major 20th century theories for the origin of the universe?
Big Bang Theory, Steady State Theory
What are the two sub-theories under the Big Bang Theory?
Closed Big Bang and Open Big Bang
What does the Big Bang Theory suggest?
there was a primeval fireball, the entire universe was compressed into a geometric point until it started expanding (raisin bread analogy)
What does the Open Big Bang Theory suggest?
the universe will continue expanding
What does the Closed Big Bang Theory suggest?
the fireball will expand to its max, then mass will cause it to collapse in on itself; this could end the universe
What is the sub-theory under the Closed Big Bang Theory? What does it suggest?
Oscillating Big Bang; it’s a cycle, the universe will expand -> collapse -> expand
What does the Steady State Theory suggest?
the universe (the average density or average distance between galaxies) does not change but the universe will continue expanding; H atoms will appear out of nothing every 500 million years, slowly forming new galaxies to keep the average distance between galaxies the same
Newton’s Infinite Static Universe
in any direction, if you go far enough, you will find a star
What is Olber’s Paradox?
If Newton’s Infinite Static Universe is true, how can the night sky be dark? It should be bright like the surface of a star.
The rate at which the universe is expanding is ___. When was this discovered?
increasing; the 1990s
Who discovered the Cosmic Background Spectrum? When?
Penzias and Wilson in the mid 1960s
How did Penzias and Wilson discover the Cosmic Background Spectrum?
The designed an antenna meant to minimize background noise (static). There was one bit of noise they couldn’t locate or eliminate.
What is the significance of the Cosmic Background Spectrum?
It is incredibly strong evidence confirming the Big Bang Theory, by confirming predictions made by the Theory. It also disproved the Steady State Theory.
What is the Cosmic Background Spectrum?
microwaves; radiation left over from an early stage in the development of the universe; thermal radiation assumed to be left over from the “Big Bang” of cosmology
What does the Cosmic Background Spectrum mimic?
black body 3º above absolute zero
Why would the universe be emitting microwaves at 3º above absolute zero?
The Big Bang would have been hot at first, then cooled off to about 3º above absolute zero.
The Big Bang stage of the history of the universe was the point of ___.
formation
What are the 7 stages of the history of the universe?
1- Big Bang2- Inflationary3- Hadron4- Lepton5- Radiation6- Matter7- Present
What did the Inflationary stage in the history of the universe involve?
very rapid expansion in a very short amount of time
During the Hadron stage in the history of the universe, ____ and similar particles came to be. There was ____ radiation and ___.
protons; electromagnetic; energy
During the Lepton stage in the history of the universe, ____ and similar matter came to be. There was ____ radiation and ___.
electrons; electromagnetic; energy
During the Radiation stage in the history of the universe, the temperature ___, forming ___ stars. __ is converted into He. The universe is __% He.
During the Radiation stage in the history of the universe, the temperature cools, forming cool stars. H is converted into He. The universe is 25% He.
Matter stage of the history of the universe: Matter + Anti-Matter = ?
large release of energy equal to E=mc^2
Why isn’t the Matter + Anti-Matter process a perfectly symmetrical process?
there is more matter than anti-matter
What is converted to create Carbon?
He
Why wasn’t Carbon formed prior to the present?
the universe was too cool to form C by the time He was formed
What is Hubble’s Law (2 observations)?
the observation that: 1- objects observed in deep space have a Doppler shift (redshift/blueshift), meaning they are moving away from Earth at a relative velocity2- this Doppler-shift-measured velocity is approximately proportional to the objects’ distance from the Earth
What is the significance of Hubble’s Law?
It is a direct, physical observation of the expansion of the universe.
___ ___ are the brightest stars.
Red Giants
The Nebula Theory is about the origin of…
a solar system.
What happens in ice skater physics?
Pulling in then rapid spinning
What happens in pizza dough physics?
Flatten out; start to collapse into a disc
Are planets common or rare?
Common
What was the goal of the Kepler Mission?
To find planets around other stars
By what process do planets form?
Accretion
Accretion
Rocks and things collide, gravitational forces hold them together; it grows as it accretes more stuff
Why does a red nebula appear red?
Spectral emission line from hydrogen gas
Why does a blue nebula appear blue?
Dust grains; light from very hot stars bounces off of dust grains
What are the dark areas in the Horsehead Nebula?
Dust
Where is the Orion Nebula?
The center “star” of Orion’s sword in the Orion constellation
What is the center star of Orion’s sword really?
newly formed Trapezium Star Cluster
Giant molecular clouds are sites for…
star formation.
What is a proplyd?
Protoplanetary disk rotating disk of gas surrounding a newly formed solar system
While studying radio waves in the Orion region, we can see…
molecules (carbon monoxide) and ionized hydrogen
What is HII?
Ionized hydrogen
How do stars get rid of extra material?
emit radio waves
How is hydrogen ionized?
It loses an electron via UV light
Super cool stars emit ___ light rather than red light.
infrared
Why is it hard for astronomers to know the sequence of star formation?
all the stages present in the Orion Nebula are in the same position in the sky (from our point of view), rather than in a line.
HII forms around hot (O and B) stars and emits a lot of ___ ___.
UV light
Who was Macier? What did he do?
French astronomer in the 1800s made a catalogue of things he could see through his telescope; he was looking for comets, so he just numbered everything that wasn’t a comet in the “Catalogue of Objects to be Ignored” (M-1, M-2, M-3, M-4, M-5, etc.)
M-16 is also known as the ____ Nebula.
Eagle
What is in M-16/ Eagle Nebula?
fairly massive O and B stars that emit a lot of UV light “Pillars of Creation” evaporative gaseous globules (EGG)
What are evaporative gaseous globules (EGG)?
baby solar systems
How do stars like the Sun get rid of excess or leftover material?
nearby O and B stars emit UV light to take care of it/ clean it up
What is a star’s excess or leftover material?
nebula
How do T Tauri type stars get rid of excess material?
wild solar winds blow it away
evolution
slow change that takes place over a long period of time
stellar revolution
changes that take place quickly in one individual star
What is hydrostatic (gravitational) equilibrium?
In a star, if the forces of gravity and pressure balance exactly, the star is in equilibrium.
In a star, ___ pushes in and ___ pushes out.
gravity; pressure
The Sun and stars like it have __ solar mass.
1
What is the most important property in determining all the other properties of a star?
mass
What other property can also be important in determining all the other properties of a star?
chemical composition
A Red Giant with small mass produces ___ ___, leaving behind a ___ ___.
planetary nebula; white dwarf
A Red Giant with large mass produces ___ __ ___, leaving behind a ___ ___ or a ___ ___.
Type II supernova; neutron star; black hole
A white dwarf can slowly cool to become a ___ ___.
black dwarf
A white dwarf can accrete material to create a ___, leaving behind the ___ ___.
nova; white dwarf
A white dwarf can accrete material to create a ___, leaving behind ____.
Type I supernova; nothing
If a black hole has a ___ ___, it will accrete material and emit ___ ___.
binary companion, x-ray radiation
What is the approximate solar mass of a low-mass star?
less than 8 solar mass
The stellar core remaining in the middle of a low-mass star’s planetary nebula is a ___ ___.
white dwarf
How does a low-mass star produce a planetary nebula?
It ejects its outer layers.
What is the approximate solar mass of a high-mass star?
more than 8 solar mass
The result of a Type II supernova depends on…
the original mass of the high-mass star that exploded as a Type II supernova
If a high-mass star is extremely massive, its resulting Type II supernova will leave behind a ___ ___. Otherwise, it will leave behind a ___ ___.
black hole; neutron star
If a white dwarf has a companion star, it can gravitationally attract material from its companion in a process known as ____.
accretion
Under what circumstances can a black hole be detected?
If the black hole has a binary companion star, the black hole’s strong gravitational pull can accrete matter from its companion. The material spirals around the black hole and emits large amounts of X-ray radiation, detectable with X-ray telescopes.
Which live longer, high-mass or low-mass stars?
low-mass
What is a protostar?
the object that initially forms when a cloud of dust and gas begins to collapse inward to form a star
What is the process of the Sun’s evolution?
The Sun collapses onto the Main Sequence. It releases its solar nebula. The Sun is sustained on nuclear fusion reactions (4 H -> 1 He). Eventually, the hydrogen is exhausted, and it must burn helium instead. The Sun is now at the first Red Giant stage. There will be a helium flash. Now, the Sun has reached the second Red Giant stage. It is very unstable. It blows up its outer shell and ejects planetary nebula. Helium burning ceases. The planetary nebula dissipates into space, and the core collapses into a white dwarf. Eventually, it will cool to a black dwarf.
When does a star officially become a star?
when hydrogen is converted to helium in the core
A star expands when ___ runs out.
hydrogen
___ and ___ overcome the repulsive force between electrons during the Main Sequence stage, causing nuclear fusion reactions.
Heat; pressure
Hydrogen and helium both have a ___ charge.
positive
When hydrogen runs out and the star expands, the ___ core will begin to collapse and the ___ shell outside that core will expand and cool.
helium; hydrogen
Because helium and hydrogen have the same charge (positive) and like charges repel, heat and pressure are needed to force ___ ___ reactions.
nuclear fusion
When the helium core is contracting or collapsing, gravity wins. The temperature of the helium core ___. A new nuclear fusion reaction occurs: helium -> ____. This is known as the ___ ___.
increases; carbon; Triple-alpha Process
helium flash
all the nuclear fusion reactions start igniting at once
Triple-alpha Process
set of nuclear fusion reactions by which helium is transformed into carbon
Stars with 1 solar mass can’t generate enough heat or inward ____ force to generate carbon fusion reactions, so they collapse into the ___ ___ stage.
gravitational; white dwarf
variable star
stars that change in brightness
What evidence do we have to prove the theoretical predictions regarding stellar evolution?
variable stars
A Cepheid star is a ___ star.
variable
The universe isn’t old enough for any less-massive __ stars to have evolved off the main sequence yet.
M
A Cepheid star has a ___ day cycle of bright -> faint -> bright -> faint.
5 1/2
catalyst
expedites reaction
Any fission reactions with elements lighter than iron (Fe) ___ energy rather than ___ energy.
require; produce
List carbon, hydrogen, silicon, and iron in order from most to least massive.
Fe, Si, C, H
___ is the line between fission and fusion.
Iron (Fe)
A supernova emits as much energy in a few years as the Sun does in ____ years.
10 billion
A supernova recycles stardust and…
seeds a new age of stars.
Sirius is a ___ ___ star.
white dwarf
Sirius doesn’t move in a straight line across the sky, because it is…
orbiting something in a binary system.
Sirius A is ___ than Sirius B. They are in a ___ orbit.
brighter; binary
A white dwarf is about the size of ___.
Earth; about 10,000 miles diameter
large mass in small volume equals
high density
Degenerate Electron Gas
electrons are packed as tight as possible
White dwarfs have different laws, because they are made of ___ ___ ___.
degenerate electron gas
Typical ___ laws do not apply to degenerate electron gases.
gas
degenerate electron gas: The proportions of ___, ___, and ___ are not constrained. Changing one does not affect the others.
pressure, volume, temperature
Adding more mass to white dwarfs decreases their ___, because no ___ is pushing out.
size; pressure
There are no nuclear reactions going on in a white dwarf star whatsoever. How do we know?
It there were, it would constantly be exploding. As pressure increases in a white dwarf, size does not increase.
As pressure increases in a white dwarf, ___ does not increase.
size
Chandrasekhar Limit
upper mass limit for white dwarfs If a white dwarf is more than 1.4 solar mass, it is unstable and will collapse into a neutron star.
If a white dwarf is more than ___ solar mass, it is unstable and will collapse into a neutron star.
1.4
neutron star
big ball of neutrons condensed into the nucleus of an atom a ball of neutrons (neutral charge) can be squeezed tighter than a ball of protons (positive charge) or electrons (negative charge)
When it comes to protons and electrons, opposites ___.
attract
Who discovered neutron stars? When?
Jocelyn Bell-Burnell 1967
How did Jocelyn Bell-Burnell discover neutron stars?
by accident while studying twinkling stars and interplanetary medium She found a “bit of scruff” in her data (radio waves chart) accurate to a billionth of a second. It was bright then faint, etc.
Crab Nebula Pulsar
bright and faint every .033 seconds (the star is “turning on and off” 33 times per second)
pulsars
neutron stars
What happened in space on July 4, 1054 AD?
Type II supernova explosion It was so bright, it was visible during the day for a month.
rapidly rotating neutron star
When magnetic poles (north and south) point toward us, the star is “on.” Otherwise, it’s “off.”
Synchrotron Radiation
the radio waves emitted along the direction of an electron’s motion; electromagnetic radiation emitted when charged particles are accelerated radially
neutron star mass limit
between 2-3 solar mass
What happens if a neutron star exceeds the mass limit?
it’s unstable and becomes a black hole
Adding mass does not ____ size.
increase
nova
exploding; relatively small explosion
A nova only involves the ___ ___ of a white dwarf.
surface layers
What shape is the binary system orbit of a red giant and white dwarf?
figure 8
Type II supernovas are the result of…
massive red giants with iron cores.
Type I supernovas come from…
white dwarfs the exceed the Chandrasekhar limit.
Supernovas are ____.
explosions
Both types of supernovas blow ___ into space and make heavy ___.
atoms; elements
What do the atoms blown out by supernovas do?
combine with other stuff to make Earth and other things
What is a static black hole?
a black hole that doesn’t move and is isolated
escape velocity
minimum speed needed to escape an object; minimum speed to throw something into orbit from a planet
The escape velocity increases if the ___ ___ increases.
gravitational force
How would the gravitational force increase?
compress the body
If you compress something so much that the escape velocity exceeds the speed of light, what is produced?
a black hole
___ can go faster than the speed of light.
Nothing
Orbit depends on ___ not ___.
size; mass
If the Sun somehow became a black hole, what would the Earth do?
It would stay in orbit, no change
If something is in a stable orbit around a star that becomes a black hole, it will…
stay in orbit.
The event horizon is also known as the ___ ___.
Schwarzschild Radius
The escape velocity at the event horizon equals…
exactly the speed of light.
You can cross ___ at the event horizon, but you can’t cross ___.
inward; outward
How would one escape the event horizon?
travel at the speed of light
The singularity is a ___ ___.
geometric point
What is the radius and volume of the singularity?
0
Approximately, what is the mass of the singularity?
a lot
What is the density of the singularity?
infinity
What are the three parts of a black hole?
singularity, event horizon/Schwarzschild Radius, photon sphere
How can light escape a black hole?
if it is emitted from the exitcone axis, it will escape on a straight path
What happens to light that unsuccessfully tries to escape a black hole?
it orbits the black hole
Black holes in ___ orbits can be seen with ___ telescopes.
binary; x-ray
The spinning speed of a neutron star is measured in ___.
milliseconds
What are the three characteristics of a rapidly spinning black hole?
singularity, ergosphere, stationary limit
What will happen if you are in the ergosphere of a rapidly spinning black hole?
you will spin along with the black hole
It is possible to extract energy from a rapidly spinning black hole, but the black hole will…
slow down
How do you extract energy from a rapidly spinning black hole?
go past the stationary limit, gain energy by spinning along with the black hole, and eject from the ergosphere with more energy than you went in with
What is the theory about the center of galaxies?
there is a supermassive black hole there emitting energy by spinning
Stephen Hawking combined ___ ___ and ___ ___ to study ___ ___.
general relativity; quantum mechanics; black holes
Stephen Hawking concluded that primordial black holes ___.
evaporate
primordial black hole
hypothetical type of black hole that is less massive and formed by the extreme density of matter present during the universe’s early expansion (rather than by the gravitational collapse of a large star)
Quantum mechanics is based on ___.
probability
The singularity of a black hole is predicted through quantum mechanics. The farther from the black hole’s center, the ___ likely the singularity is to be there.
less
According to Hawking, what will happen if the singularity is outside the event horizon/Schwarzschild Radius?
the black hole will explode/evaporate and emit gamma rays
How long would it take for a less massive or primordial black hole to evaporate?
longer than the age of the universe
What are the four parts involved with a wormhole?
black hole (our universe), singularity, Einstein-Rosen Bridge (the actual wormhole), white hole (other universe)
white hole
things can come out, but they can’t go in (the opposite of a black hole)
How fast would you have to go to get through a wormhole? Why?
faster than the speed of light; the singularity oscillates
Gravitational force depends on ___ and ___.
mass; distance
An accretion disk gets really ___ and emits ___ radiation.
hot; x-ray
An x-ray source may be a ____ ____.
black hole
A neutron star has ___ mass than a black hole.
less
What does a neutron star have in common with a black hole?
both have accretion disks that emit x-ray radiation
Describe the interior structure of a 1 solar mass star during the second red giant stage.
C core with shells burning He to C and H to He
Between the first and second red giant phases of its life, a 1 solar mass star like the Sun fuses ___ to ___ in its core and ___ to ___ in a shell.
fuses He to C in its core and H to He in a shell.
A 0.5 solar mass star has a main sequence life time that is ___ ___ ___the main sequence life time of the Sun.
much longer than
A star with more than 3 solar masses at the end of its life will become a ____ ___.
black hole
If one white dwarf has 1 solar mass and another has 1.3 solar masses, which has the larger radius?
1.3 solar mass white dwarf
If you threw salt in a Bunsen burner flame, and observed it through a spectroscope as it vaporized into a hot sodium gas, what type of spectrum would you see?
emission spectrum of sodium
How will the light gathering power of a 100 inch telescope compare to the light gathering power of a 200 inch telescope?
One fourth as much
Two stars of the same luminosity are plotted on an H-R diagram. Star A is hotter than Star B. This means…
Star A is smaller than Star B
Star A has many spectral absorption lines in the red, and Star B has many spectral absorption lines in the blue. Which is hotter?
Impossible to tell with just this information.
Where are the globular clusters in the Milky Way located?
Halo
Where are the oldest stars in the Milky Way located?
Halo
What is the least massive class of galaxy?
Dwarf elliptical
