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239 Cards in this Set

  • Front
  • Back
Who proved conclusively that galaxies exist beyond the Milky Way?
Edward Hubble
What did Hubble discover about the distance and speeds galaxies travel?
The more distant a galaxy is, the faster it moves away from us
What does the motions of the galaxies tell us about the universe?
Implies that:
1. the entire universe is expanding, and
2. the age of the universe is FINITE
What element has the Universe's galaxies used through star recycling producing new elements for future generations of stars?
Hydrogen gas
How many galaxies are in the observable Universe?
Over 100 Billion galaxies
What is the term for the study of the overall structure and evolution of the Universe?
Cosmology
How many categories of galaxies are there?
Three or 3 basic types of galaxies
List the three (3) basic types of galaxies:
1. spiral galaxies
2. elliptical galaxies
3. irregular galaxies
What type of galaxy looks like flat white disks with yellowish bulges at their centers, and usually display beautiful spiral arms??
Spiral galaxies
What type of galaxy looks redder and more rounded in one direction than in the other than a spiral galaxy?
Elliptical galaxies
What type of galaxy looks like a football?
Elliptical galaxies
What type of galaxy contains very little cool gas and dust though they often contain very hot ionized gas?
Elliptical galaxies
What type of galaxy appears neither disklike nor rounded?
Irregular galaxies
What causes the different colors of galaxies?
From the different kinds of stars that populate
What type of galaxy's appearance is a result of containing stars of all different colors and ages?
Spiral galaxies
which appear white often with spiral arms
What type of galaxy's appearance is a result because old, reddish stars produce most of their light?
Elliptical galaxies which are football shape and reddish in color
What is the term used for galaxies that contain as few as 100 million or
8
10 stars?
Dwarf galaxies
What is the term used for galaxies that contain more than a trillion or
12
10 stars?
Giant galaxies
List the 3 distinct characteristics found in a spiral galaxy?
1. disk
2. bulge
3. halo
What characteristic of a spiral galaxy that is difficult to see in photographs because its stars are generally dim and spread over a large volume of space?
The Halo
How many distinct populations of stars make up the Milky Way and other spiral galaxies?
1. disk population
2. spheroidal population
What component of a galaxy is the flat disk in which stars follow orderly, nearly circular orbits around the galactic center?
Disk Component
What does the disk component of a galaxy always contain?
An interstellar medium of gas and dust
T or F
The amounts and proportions of the interstellar medium of a galaxy in molecular, atomic, and ionized forms differ from one spiral galaxy to the next.
True
What makes up the spheroidal component of a spiral galaxy?
1. the Bulge
2. the Halo
What component of a galaxy has stars that have orbits with many different inclinations?
Spheroidal component
What component of a spiral galaxy contains litle cool gas and dust?
Spheroidal component
T or F
Not all spiral galaxies have both a disk and a spheroidal component.
False,
All Spiral galaxies have both a disk and spheroidal component
What type of spiral galaxies appear to have a straight bar of stars cutting across the center, with spiral arms curling away from the ends of the bar?
Barred Spiral Galaxies
T or F
Astronomers suspect that the Milky Way is a Barred Spiral Galaxy because it's bulge appears to be somewhat elongated
True
What type of spiral galaxy do astronomers suspect the Milky Way to be?
Barred Spiral Galaxy
What type of galaxy have disk and spheroidal components but appear to lack spiral arms?
Lenticular Galaxies
What word is means "lens-shaped"?
Lenticular
What type of galaxy is considered an intermediate class between spirals and ellipticals, because they tend to have less cool gas than normal spirals but more than ellipticals?
Lenticular Galaxies
What types of galaxies make up most of the large galaxies in the universe?
1. Spiral
2. Lenticular
T or F
Galaxies with obvious disks are more common among small galaxies?
False,
Galaxies with obvious disks are much RARER among small galaxies.
What type of galaxy have only a spheroidal component and lack a significant disk component?
Elliptical Galaxies
What type of galaxy look much like the bulge and halo of a spiral galaxy that is missing its disk?
Elliptical
What are elliptical galaxies sometimes called?
Spheroidal galaxies
What is the other name for Spheroidal Galaxies?
Elliptical Galaxies
T or F
The most massive galaxies in the universe are the relatively rare giant elliptical galaxies.
True
T or F
The vast majority of elliptical galaxies are small.
True
What is the most common type of galaxy in the universe?
Small elliptical galaxies
What is the name for the particularly small ellipticals with less than about a billion stars?
Dwarf Elliptical Galaxies
How many dwarf elliptical galaxies belong to the Milky Way's Local Group?
at 10 dwarf elliptical galaxies are in the Local Group
Where are dwarf elliptical galaxies often found near?
Larger spiral galaxies
T or F
Elliptical galaxies can contain either very little dust or cool gas, or contain substantial amounts of very hot gas.
True
What is the low-density, X ray-emitting gas that is found in large elliptical galaxies similar to?
The gas in the hot bubbles created by supernovae and powerful stellar winds in the Milky Way
When an elliptical galaxy lack cool gas, what happens to their star formation?
Elliptical galaxies that lack cool gas generally have little or no ongoing star formation.
Why do elliptical galaxies tend to look red or yellow in color?
They do not have any of the hot, young, blue stars found in the disks of spiral galaxies
What is the term for the galaxies that do not fall into either spiral or elliptical categories?
Irregular galaxies
What is the term for a miscellaneous class of galaxies, encompassing small galaxies?
Irregular Galaxies
What type of galaxy is the Magellanic Clouds?
Irregular Galaxy
What is the type name for large peculiar galaxies that appear to be in disarray?
Irregular Galaxies
What type of galaxy is characterized by blobby-like star systems that are usually white and dusty, like the disks of spirals, and their colors tell us that they contain young, massive stars?
Irregular Galaxies
T or F
Among nearby galaxies, only a small percentage of galaxies as large as the Milky Way are irregular.
True
T or F
Distant galaxies are more likely to spiral shape than nearby galaxies.
False,
Distant galaxies are more likely to be IRREGULAR in shape than nearby galaxies
Why do we think that irregular galaxies were more common when the universe was younger?
Because we see that the more distant we look, the we see more frequent the irregular galaxies.
The light from farther galaxies takes longer to travel than closer.
What shape of model did Edwin Hubble use to classify galaxies?
a tuning fork
Where on the "tuning fork" by Edwin Hubble do elliptical galaxies appear
On the "handle"
What is the designation symbol for elliptical galaxies on the Edwin Hubble model?
letter:
E
The larger the number next to the letter on the Hubble model for galaxies, the __________ the elliptical galaxy.
The larger the number next to the letter on the Hubble model for galaxies, the FLATTER the elliptical galaxy.
What is the shape of an EO galaxy?
A Sphere
What is the shpae of an E7 galaxy?
Highly elongated.
What is the designation symbol for ordinary spirals galaxies?
Letter:

S
What is the designation symbol for barred spiral galaxies?
Letters:

SB + lower case letter a, b,c
The bulge size ________ from a to c.
The bulge size of barred spiral galaxies decreases from a to c
Which barred spiral galaxy has a larger bulge,

SBb or SBa
SBa has the larger bulge size
As the bulge size of barred spiral galaxies decrease, what happens to the amount of dusty gas?
As the bulge size of barred spiral galaxies decrease the amount of dusty gas INCREASES
What is the designation symbol for Lenticular galaxies?
Letters:
SO
What is the designation symbol for Irregular galaxies?
Letters:
Irr
T or F
The Hubble classification system for galaxies has not led to easy answers about their nature.
True
T or F
Many galaxies are gravitatonally bound together with neighboring galaxies.
True
What is the term for the loose collections of up to a few dozen spiral galaxies?
Groups
What is the characteristic common to our Local group of galaxies?
It is a group of spiral galaxies
What type of galaxy is particularly common in clusters of galaxies, containing hundreds and sometimes thousands of galaxies?
Elliptical galaxies
What type of galaxies can be seen in clusters that extend over more than 10 million light-years?
Elliptical galaxies
What is the term for the apparent shift in a star's position as Earth orbits the Sun?
Parallax
In order to use parallax to determine a star's distance, what measurement is necessary to know?
The distance from the Earth to the Sun or an astronomical unit or AU
How do astronomers measure the AU?
radar ranging
What is the term for the technique used by astronomers to measure the AU?
Radar ranging
What is the term for the technique used by astronomers in which radio waves are transmitted from Earth and bounced off Venus?
Radar ranging
At what speed to radio waves travel?
The speed of light
What is the term for a light source of a known, standard luminosity?
standard candle
T or F
For any star that is a twin of our Sun, with a spectral type G2, should have the same luminosity as the Sun.
True
Using the luminosity of the Sun, what do we use to estimate a star's distance?
The Inverse Square Law of Light
What is the formula for the inverse square law of light?
distance = square root of
luminosity/
4pi X apparent bright
What unit of measure do we use for most cosmic distance measurements?
Standard candles
T or F
No astronomical object is a perfect standard candle.
True
T or F
All main-sequence stars of a particular spectral type have about the same luminosity.
True
What nearby star cluster's luminosity was relied upon to calibrate the luminosities on a standard H-R diagram?
Hyades Cluster in the constellation Taurus
What is the term for the technique of determining distances by comparing main sequences in different star clusters?
Main-sequence fitting
T or F
Main-sequencing fitting works well for measuring distances to star clusters through the Milky Way, but not for measuring distances to other galaxies.
True
Why doesn't main-sequence fitting work well for measuring star cluster distances beyond the Milky Way?
Most main-sequence stars are to faint to be seen in other galaxies.
What stars are used for measuring the distances to galaxies?
Cepheid variable stars
What is another name for the Cepheids?
Cepheid variable stars
Why are the Cepheids also known as the Cepheid variable stars?
Because they vary in brightness in our sky, alternately becoming dimmer and brighter with periods ranging from a few days to a few months.
T or F
Each Cepheid has its own particular time period between peaks in luminosity.
True
When and by whom discovered that the periods of Cepheids are very closely related to their luminosities?
Henrietta Leavitt
What did Henrietta Leavitt discover about the Cepheids?
The longer the period(days to months), the more luminous the star
What is the term used to describe the relationship between the Cepheids' length of period and their luminosity?
a Period-Luminosity Relation
Why do the Cepheids' luminosity vary?
They have a problem in matching the amount of energy their surfaces radiate with the amount welling from the core.
In order to seek equilibrium, the upper layers of a Cepheid variable star alternately expand and contract causing the luminosity to rise and fall.
Why does the period-luminosity relations is true for the Cepheids?
Because larger Cepheids take longer to pulsate in and out in size
In recent years, what standard candle has proved to be the most valuable of several techniques in estimating distances beyond those for which we can observe Cepheids?
Using white dwarf supernovae
What are thought to be white dwarf supernovae?
Exploding white dwarf stars that reach the 1.4 solar-mass limit.
T or F
All white dwarf supernovae should all have nearly the same luminosity, because they all come from stars of the same mass that explode in the same.
True
T or F
White dwarf supernovae are quite rare.
True
How bright are white dwarf supernovae at their peak?
10 billion solar luminosities
Where did Edwin Hubble make his discovery re: distances to other galaxies?
Mt. Wilson in California
What galaxy did Hubble study to prove that it sat far beyond the outer reaches of the stars in the Milky Way?
Andromeda GAlaxy
Before Hubble made his discovery @ the Andromeda Galaxy, what was our belief @ the Universe?
That the Milky Way was the entire universe
The spectra of most spiral galaxies tend to be _____shifted?
The spectra of most spiral galaxies tend to be redshifted.
How does redshifting occur?
When the object emitting the radiation is moving away from us.
What was Hubble's great discovery in 1929?
The more distant galaxy, the greater its redshift and hence the faster it moves away from us.
What had Hubble discovered about the Universe in 1929?
That the entire Universe is expanding
T or F
Studies conducted after Hubble have determined that galaxies receding galaxies are farther away than Hubble thought.
True
What is Hubble's Law?
v = H X d
0
v= recession velocity
d=distance
H = Hubble's contant
0
What is the symbol for "Hubble's naught"?
H
0
What does the speed of a galaxy depend on?
Its distance
List the difficulties in using Hubble's Law to galactic determine distances?
1. Galaxies do not Hubble's law perfectly
2.When galaxies behave well, the distances are only as accurate as our best measurement of Hubble's Constant
Why don't galaxies obey Hubble's Law?
Nearly all galaxies experience gravitational tugs from other galaxies, altering their speeds from the "ideal" values predicted by Hubble's Law
What is the most serious problem why most nearby galaxies do not obey Hubble's Law?
The galaxies in the Local Group are gravitationally bound together with the Milky Way and therefore not moving away from us.
Which galaxies, near or distant, does Hubble's Law work well
Distant galaxies
T or F
The Hubble telescope has helped us obtain an accurate value for Hubble's naught?
True
What is the value of Hubble's naught? (H
0)
between 20 and 24 kilometers PER second PER million light years
For every million light years of distance away from, what is a galaxy's speed away from us?
20-24 km/s

20 - 24 kilometers PER second
What would be the moving away speed of a galaxy be if it were 100 million years away from us?
2,000 - 2,400 km/s
List the interlocking links in the chain of determining cosmic distances.
1. radar
2. parallax
3. main-sequence fitting
4. Cepheids or cepheid variables
5. distant standards
6. Hubble's Law
How do we measure the Earth-Sun distance?
Radar ranging which is Bouncing radio waves off Venus and using some geometry
How do we measure the distances to nearby stars?
By observing how their positions appear to change as Earth orbits the Sun.
These distance rely on our knowledge of the Earth-Sun distance, which is determined with radar ranging
How do we measure the distances of star clusters in our galaxy?
Main-sequence fitting;
1. know that Hyades star in Milky Way through parallax.
2. comparing the apparent brightnesses of its main-sequence stars to those of stars in other clusters gives us the distances to these other star clusters in our galaxy
How do we learn the distance of a Cepheid?
1. by main-sequence fitting, we learn the precise period-luminosity relation for the Cepheids.
2. When we find a Cepheid in a more distant star cluster or galaxy, we can determine its true luminosity by measuring the period between its peaks in brightness and then use this true luminosity to determine the distance.
How do we measure distances using distant standards?
1. By measuring distances to relatively nearby galaxies with Cepheids, we learn the true luminosities of white dwarf supernovae and other distant standard candles, enabling us to measure great distances through the universe.
How do we measure using Hubble's Law?
1. distances measured to galaxies with white dwar supernovae and other distant standards allow us to measure Hubble's constant, H
0.
One we know Hubble's constant, we can use Hubble's law to determine a galaxy's distance from its redshift
Why do we assume that the universe cam into being at a single moment in time?
Because the expansion of the Universe implies that the Universe came into being at a single moment in time.
What is the nickname we have assigned to "single moment in time" that the Universe began?
The Big Bang
What is the name of the idea that the matter in the universe is evenly distributed, without a center or an edge, is called?
Cosmological Principle
Can we prove the Cosmological Principle is true?
No.
What is often used to more accurately represent what we believe the expansion of the Universe is?
the surface of a balloon as a sheet of rubber that extends to infinity in all directions.
T or F
In the balloon analogy to the universe, the balloon's spherical surface has no center and no edges.
True
What does

1/H
0
tell us about how long the universe has been expanding?
Because it is the same at all locations in the universe at a particular moment in time
Based on the value of Hubble's constant, what are current estimates of the age of the universe?
between 12 and 15 billion years, the best available evidence putting the age of the universe at 14 billion years old
What is the term that refers to the amount of time since the light we see from a distant object was emitted?
For ex., we are seeing an object that is what it actually looked like 400 million years ago.
Lookback time
What is the term for the difference between the current age of the universe and the age of the universe when the light left the object?
Lookback time
If lookback time = 400 million years, what does this mean in terms of how the light traveled to us?
It means the light really traveled through space for a period of 400 million years to reach us.
What is an object's lookback time directly linked to?
It's redshift.
What is the term that describes what happens to photons as the universe expands?
Cosmological redshift
What happens to photons as the universe expands?
The Universe stretches out all the photons within, shifting them to longer, redder wavelengths.
What tells us how much space has expanded during the time since light from the galaxy left on its journey to us?
Cosmological redshift
Does the universe have a horizon, a place beyond which we cannot see?
yes
What is the place beyond the universe which we cannot see?
Cosmological horizon
What is the cosmological horizon mark?
The limits of the observable universe is a boundary of time
T or F
The limits of the observable universe is a boundary of space.
FALSE!
The limits of the observable universe is a boundary of TIME.
T or F
We cannot see any object with a lookback time greater than 14 billion years.
True
What is the term given to the formation and development of galaxies?
galaxy evolution
T or F
We know less about galaxy evolution than we do about the lives of the stars.
True
What are used like time machines to observe the life histories of galaxies?
powerful telescopes
What do the most successful models for galaxy formation assume?
1. Hydrogen and helium gas filled all of space more or less uniformly when the universe was very young;
2.the distribution of matter in the universe was not perfectly uniform -certain regions of the universe started out ever so slightly denser thatn others
What caused the slightly denser regions to slow their expansion?
Gravity
What happened to the denser regions in the new universe over time?
The expansion of the denser regions halted and reversed
What was created by the result of the new universe's denser regions' expansion halting and reversing?
The material within began to contract and formed PROTOGALACTIC CLOUDS
What type of cosmic phenomena is thought to have been the basis of the formation of the Milky Way?
A PROTOGALACTIC CLOUD
How did protogalactic clouds form spiral galaxies?
they cooled initially as they contracted, radiating away their thermal energy, and the first generation of stars grew from the densest, coldest clumps of gas.
T or F
It is thought that stars formed quickly and died quickly early in the life of the universe
True
What is the term for the population of stars that orbit the galactic center in a fairly flat plane in a spiral galaxy?
disk population
What is the term for the population of stars with more randomly oriented orbits in a spiral galaxy?
Spheroidal population
When did the stars that make up the spheroidal population formed, before or after the galaxy's rotation become organized?
Before the galaxy's rotation become organized
Why do spheroidal population stars have orbits oriented in many different ways around the galactic center of a spiral galaxy?
Because the spheroidal population consists of stars that were born BEFORE the galaxy's rotation became organized.
What population of stars in a spiral galaxy consist of stars born AFTER the gas in the protogalactic cloud settled into a rotating disk?
Disk population
Why do stars in the disk population of a spiral galaxy have similar orbits around the center of the galaxy?
Because disk population stars were born AFTER the gas in the protogalactic cloud settled in a rotating disk
How are all protogalactic clouds thought to have begun?
Gravity collecting matter around a pre-existing density enhancement.
List the 2 possible reasons for why did galaxies end up in the different types we see today?
1. galaxies began with slightly different conditions in their protogalactic clouds

2. galaxies may have begun their lives similarly but later changed due to interactions with other galaxies
List the 2 possible explanations for the differences between spiral galaxies and elliptical galaxies:
1. protogalactic spin
2. protogalactic density
What is the term for the spin of the protogalactic cloud from which a spiral or elliptical galaxy formed?
Protogalactic spin
What type of galaxy would form from a protogalactic cloud if it had a significant amount of angular momentum?
Spiral galaxy
What would have been the result of a significant amount of angular momentum in a protogalactic cloud?
It would have rotated quickly as it collapsed.
The galaxy produced would have tended to form a disk
What would have happened if the protogalactic cloud had little or no angular momentum, what shape might the galaxy be?
Elliptical galaxy, football shaped
What would be the result of a protogalactic cloud with relatively high gas density?
It would radiate energy more effectively and cooled more quickly.
What would be the result of a protogalactic cloud which radiated energy more effectively and cooled more quickly?
It would allow more star formation
What would happen if star formation proceeded fast in a protogalactic cloud that had relatively high gas density?
All the gas could have been turned into stars before any of it had time to settle into a disk.
What type of galaxy is thought to may have formed from a relatively high gas density protogalactic cloud?
Elliptical galaxy
What type of galaxy is thought to may have formed from a lower-density cloud that formed stars more slowly?
Leaving more gas, the cloud would have formed into a disk of a spiral galaxy
What evidence supports the idea that it is the density of the protogalactic cloud that may be the cause for the differentiation of the galaxies?
A few giant elliptical galaxies look very red even after we have accounted for their large redshifts.
Apparently they do NOT have blue or white stars at all, indicating new stars no longer form with these galaxies
When is it thought that stars formed in an elliptical galaxy?
Before a disk could develope
T or F
Galaxies rarely evolve in perfect isolation.
True
T or F
Galactic collisions must have occurred more frequently in the distant past, when the universe was smaller and the galaxies were closer together.
True
T or F
Computer models show that it is possible for 2 spiral galaxies to collide and form an elliptical galaxy.
True
What type of galaxies dominate the galaxy populations at the cores of dense clusters of galaxies?
Elliptical galaxies
What exists at the centers of many dense galaxy clusters?
Central dominant galaxies
What is the term for the giant elliptical galaxies that apparently grew to a huge size by consuming other galaxies through collisions that are in the centers of many dense galaxy clusters?
Central dominant galaxies
What is the term for the "swallowing up" of smaller galaxies by larger galaxies?
Galactic cannibalism
List the 2 possible ways that elliptical galaxies may have formed?
1. result of an unusually slow-rotating or high-density protogalactic cloud; or
2. later collisions and mergers of spiral galaxies
What is the term for a galaxy in which stars are forming at an unusually high rate?
Starburst Galaxies
Are there a lot of starburst galaxies?
No, a relatively small number of galaxies
How often does the Milky Way produce a new star?
One new star per year.
T or F
Some starburst galaxies form new stars at rates exceeding 100 per year.
True
If star formation rate is 100 times that of the milky Way, what would be the rate of supernovae?
100 times that of the Milky Way
What is the term for the hot gas that erupts from a gigantic bubble through any gaseous disk when individual supernovae merge?
Galactic wind
What is the term for the unusually bright galactic centers of some galaxies?
Active Galactic Nuclei
What is the term for the most luminous active galactic nuclei at the centers of unusually bright galactic centers?
Quasars
In some cases, how much light do quasars emit?
More light than 1,000 galaxies the size of the Milky Way
Where do we primarily find quasars?
At great distances.
T or F
The age of the quasars are long past.
True
T or F
The objects that shine as quasars in young galaxies must become dormant as the galaxies age.
True
What is thought to be the reason for the energy output by quasars?
That the energy output by quasars come from gigantic accretion disks surrounding SUPERMASSIVE BLACK HOLES
How did the term quasar come to be?
It was thought that they were strong sources of radio emission that looked like stars through visible-light telescopes and thus, were quasi-stellar radio sources
What is the shortened name for quasi-stellar radio sources?
QUASARS
When, By whom and where were quasars discovered?
In the early 1960's by Maarten Schmidt at California Institute of Technology
What is unique about quasars?
Radio emissions lines of hydrogen are hugely redshifted from their normal wavelengths
Where do most quasars lie?
Halfway to the cosmological horizon
When is it thought that the light from these quasars emerged?
When the universe was less than one third of its present age, @ when the universe was @ 4-5 billion years old
Why are quasars so difficult to study?
Because they are so far away.
What is the term for galaxies that are nearby that have active galactic nuclei that look very much like quasars, except that they are less powerful?
Seyfert galaxies
What percent of galaxies that we see nearby are Seyfert galaxies?
@ 1 %.
T or F
The immense luminosities of quasars and other active galactic nuclei come from regions no larger than our solar system.
True
What is the term for galaxies that emit unusually strong radio waves?
Radio galaxies
Where do the radio waves of radio galaxies really emitted from?
Pairs of huge radio lobes, one on either side of the galaxy.
T or F
We often seen 2 gigantic JETS of plasma shooting out of the active galactic nucleus in opposite direction in the center of a radio galaxy.
True
What do we often see in the center of a radio galaxy that has an active galactic nucleus?
2 gigantic jets of plasma
T or F
We now suspect that quasars and radio galaxies are the same types of objects viewed in slightly different ways.
True
What seems to conceal the active nuclei of many radio galaxies?
Donut-shaped rings of dark molecular clouds
What is the term for a subset of active galactic nuclei represent the centers of radio galaxies whose jets happen to point directly at us?
BL Lac objects
What method is used to make radio-wave images that show that the light emitting regions of active galactic nuclei are less than 3 light-years across?
Interferometry
What is the accepted explanation for how radio galaxies, quasars, and other active galactic nuclei release so much energy within such small central volumes?
1.The energy comes from matter falling a supermassive black hole.
Explain how the energy is converted from matter that is falling into a supermassive black hole?
1. gravitational potential energy of matter falling toward the black hole is converted into kinetic energy
2. collisions between infalling particles convert the kinetic energy into thermal energy
3. resulting heat causes this mater to emit the intense radiation we observe
T or F
Accretion by black holes can produce light far more efficiently than nuclear fusion.
True
Why does accretion by black holes produce more light than nuclear fusion?
As much as 10-40% of the mass-energy (E=mc squared) of a chunk of matter can be converted into thermal energy and ultimately to radiation. Nuclear fusion converts less than 1% of mass-energy into photons
Do we know how black holes formed?
No.
T or F
Some astronomers have questioned the existence of black holes.
True
T or F
Black holes are common.
True
What color is the shifted emission lines for quasars' light that are coming towards us?
Blue shifted emission lines
What color is the shifted emission lines for quasars' light that is moving away from us?
Red shifted emission lines
Describe the orbital speed of objects around a black hole?
High speed, hundreds of kilometers per second
What does the word "laser" stand for?
Light Amplification by Stimulated Emission of Radiation
What is the term given to the method of observing objects using water molecules?
WATER MASERS
Microwave Amplification by Stimulated Emission of Radiation
How are water masers used to observe objects?
When certain molecular clouds circle a galaxy that amplify the microwave emission lines of water molecules, generating beams of microwaves very similar to laser beams.
How much is the mass of the central black hole in relation to the mass of the galaxy's bulge?
The mass of the central black hole is typically 1/500 the mass of the galaxy's bulge.
The growth of a central black hole must be closely linked with the _______ __ _____ _________.
process of galaxy formation
T or F
The origins of supermassive black holes remain mysterious.
True