Baylor Astronomy Test 4 - Russell, Astronomy Exam 4 - Dwight Russell, Astronomy Test 4 Dr. Russell, astronomy russell test 4
Bulge
- center of the galaxy - football shape - population II stars - little gas and dust - supermassive black hole at the center
Disk
- flattened shape, spiral arms (pop I) - both population I and population II stars - interstellar gas and dust
'Rungs' in the Distance Ladder
1. The radius of the Earth 2. Size, shape, and location of the moon 3. Size and location of the sun 4. Distances from the Sun to the planets 5. The speed of light 6. Distance to nearby stars 7. Distance to moderately distant stars 8. Distances to very distant stars 9. The shape of the universe
MW: Size
100 thousand light years across
what is the size of the milky way (in light years)?
100,000 light years
MW: Sun's position
2/3rds of the way out from the center (takes 230 million years for the sun to orbit the MW
How many stars are there in the milky way?
200 billion
MW: Stars
200 billion stars
Number of Stars in the Milky Way
200 billion stars
how many years does it take the sun to orbit the milky way?
230 million
How long does it take for the sun to go around the milky way once?
230 million years
How long does it take the sun to go around the Milky Way once?
230 million years
what is an elliptical galaxy
3 dimensional, football shaped, very little gas and dust,
Elliptical galaxy
A galaxy shaped like a round or flattened ball, generally containing only old stars. stars are distributed in an elliptical shape. pop II stars, hardly any gas or dust, smooth and elliptical in appearance, no disk, old stars only.
Irregular Galaxy
A galaxy that does not have a regular shape to fit Hubble's classification scheme. Pop I stars, young blue stars, gas and dust, galaxies in collision, no definite structure.
1. Planck Epoch
A mystery partly because we lack a quantum theory of gravity
Planck Epoch
A mystery partly because we lack a quantum theory of gravity
Planck Epoch
A mystery partly because we lack a quantum theory of gravity.
Size of the milky way
About 100,000 light years across
7. Dark Ages
Atoms exist but stars don't
Dark Ages
Atoms exists but stars don't
Dark Ages
Atoms exists but stars don't.
6. Photons, Nucleosynthesis and the Cosmic Background Radiation
Atoms form (Hydrogen and Helium) and Cosmic Background Radiation 'decouples' from matter
Photons, Nucleosynthesis and the Cosmic Background Radiation
Atoms form (Hydrogen and Helium) and Cosmic Background radiation ' decouples ' from matter
Protons, Nucleosynthesis and the Cosmic Background Radiation
Atoms form (Hydrogen and Helium) and Cosmic Background radiation 'decouples' form matter.
MW: Type of Galaxy
Barred Spiral
DL: Nearby Galaxies
Cepheids
Nearby Galaxies
Cepheids
Nearby galaxies
Cepheids
Halo
Contains Globular clusters, is spherical in shape, contains pop. II stars and very little interstellar gas and dust.
Rich Cluster
Contains thousands of individual galaxies
Tully-Fisher relation
Distant standards
Why are infrared and radio telescopes the instruments of choice for studying the galactic center?
Dust in the plane of the Milky Way obscures observations at other wavelengths.
The astronomer who originally classified galaxies into S, E, and Irr was
Edwin Hubble.
A galaxy with little cool gas or dust and no evidence of ongoing star formation is most likely a(n)
Elliptical
Which of the following types of galaxies has experienced no significant star formation during the last 10 billion years?
Elliptical
Compared to the spirals, elliptical galaxies tend to be more dusty. T/F
False
Globular clusters trace out the structure of the Galactic disk. T/F
False
Irregulars typically have very few blue stars. T/F
False
Most elliptical galaxies contain only young stars.T/F
False
Most galaxies are spirals like the Milky Way. T/F
False
Most galaxies are spirals. T/F
False
On average, elliptical galaxies are richer star forming regions than spirals. T/F
False
The Galactic halo contains as much gas and dust as the disk. T/F
False
2. The Grand Unification Epoch
Forces except gravity are unified
The Grand Unification Epoch
Forces except gravity are unified
What is the criterion for a group of galaxies to be considered a cluster?
Galaxies in a cluster are bound together by their mutual gravitational pull.
Shapely used what to determine the size and position of the center of the Milky Way?
Globular Clusters
What are the shapes and regions of the Milky Way?
Halo, Disk, Bulge
Which type of star is common in the spiral arms of our Galaxy, and found almost nowhere else?
High-mass O and B stars
DL: Further out
Hubble's Law
Farthest objects
Hubble's law
What is the sun's position in the milky way?
In the disk, about 2/3 out from the center
What effect does a spiral density wave have on the material it encounters?
It slows the material down, causing it to compress and heat up, assisting gravity in forming stars.
DL: Milky Way
Main-Sequence Fitting
Milky Way
Main-sequence fitting
Self-Propagating star formation for spiral arm formation
Need a gas cloud that starts to collapse on itself. SuperNova explosion causes the next supernova to form
DL: Nearby Stars
Parallax
Nearby Stars
Parallax
DL: Solar System
Radar Ranging
Solar System
Radar ranging
Which of the following is not one of Hubble's types of galaxies?
Seyfert spirals
"Modern" Era
Stars form - Quantum fluctuations at the time of inflation determines the distribution of matter in the universe. Denser areas are where stars will form. Gravity is the major large-scale force
8. Modern Era
Stars form. Quantum fluctuations at the time of inflation determines the distribution of matter in the universe. Denser areas are where stars will form. Gravity is the major large-scale force.
Virgo Cluster
The closest cluster of galaxies to our local cluster. Contains roughly 2000 galaxies.
Size of the Milky Way
The disk of the Milky Way galaxy is about 100,000 light years in diameter (one light year is about 9.5 x 1015 meters), but only about 1000 light years thick
Which of the following is NOT a difference between the disk and the halo of the Galaxy?
The halo population stars are primarily red in color, and there are no red stars in the disk.
What did a major discovery made by Harlow Shapley using RR Lyrae stars and globular clusters establish?
The size of the Galaxy an the Sun's position in it.
Density wave theory for spiral arm formation
The spiral arms are regions where the gas and dust are slightly denser so when objects move slowly in it they get compressed like a traffic jam (stars are like the cars) the traffic jam will be there but they are different cars
Which of the following best compares the motion of stars in the halo to the motion of the stars in the disk of the Galaxy?
The stars in the halo move in randomly-oriented orbits, while the disk stars generally stay confined to moving in the disk.
Which of the following statements describes the orbits of stars within most elliptical galaxies?
They have random orbits in three dimensions.
Cepheid variables can be used to determine the distances to the nearest galaxies. T/F
True
Herschel's attempt to map the Milky Way by counting stars led to an inaccurate estimate of the Galaxy's size because he was unaware of absorption by interstellar dust. T/F
True
Irr II galaxies may be the result of a collision, or close encounter, of two normal galaxies. T/F
True
Irregular galaxies, although small, have large star-forming (HII) regions and much ongoing star formation for their size. T/F
True
M31 in Andromeda is a bigger version of our Galaxy, and the largest member of the Local Group. T/F
True
Stars and gas in the Galactic disk move in roughly circular orbits around the Galactic center. T/F
True
The Galactic halo contains only old stars. T/F
True
The orbit of the Solar System around the Galaxy is similar to that of a planet, almost circular and in the galactic plane. T/F
True
Unlike spirals, elliptical galaxies do not contain a flattened disk. T/F
True
DL: Galaxy Clusters
Tully - Fisher Relation; distant standards
Which of these standard candles has been used to determine distances to the most distant galaxies?
Type I supernovae
The inflationary Epoch
Universe expands rapidly smaller than a proton to bigger than a melon - Supported experimentally
3. The Inflationary Epoch
Universe expands rapidly smaller than a proton to bigger then a melon - supported experimentally
4. Electroweak Epoch
Weak and electromagnetic forces act as one
Electroweak epoch
Weak and electromagnetic forces act as one
Electroweak epoch
Weak and electromagnetic forces act as one.
The Quark, Hadron and Lepton Epoch
What we think of a "normal" elementary particle form and survive
The Quark, Hadron, and Lepton Epoch
What we think of a "normal" elementary particle form and survive.
5. The Quark, Hadron, and Lepton Epoch
What we think of as "normal" elementary particle form and survive
Galaxy Clusters
White Dwarf Supernovae
A telescope searching for newly formed stars would make the most discoveries if it were pointed
Within a spiral arm
Pop I star
Young stars, typically bright blue and in the disk. Around interstellar gas and dust. Formed relatively recently.
what is a spiral arm?
a distribution of material in a pinwheel shape design
what is density?
a measure of compactness
Local group
a new level of structure in the universe above the scale of our galaxy
what is the sun's position in relation to the milky way?
about 8kpc from center (in the disk, 2/3 of the way out from center)
what is the shape of the milky way?
barred spiral
what are the three regions of the milky way?
bulge, disk, and halo
what are the characteristics of a bulge?
center of galaxy, supermassive black hole at center, football shape, population II stars, little gas/dust
Virgo Cluster
closest rich cluster to us hundreds of galaxies irregular shape large gravitational pull
what is the local group cluster?
cluster that contains milky way
Pop I
contain young bright and blue stars; young lives; surrounded by interstellar dust
Population I Stars
contain young stars, all colors including blue gas and dust present
what is the self propagating star formation theory?
creation & explosion of stars can create waves to trigger next round of star formation (possible spiral structure cause)
what could be considered similar to a traffic jam?
density wave theory
what is the seventh rung on the distance ladder?
distance between moderately distant stars
what is the sixth rung on the distance ladder?
distance between stars
what is the fourth rung on the distance ladder?
distance between sun and planets
what is the eighth rung on the distance ladder?
distance between very distant stars
Which type of galaxy exhibits the largest range of sizes and masses?
elliptical
a galaxy with very little or no interstellar gas and dust is _________
elliptical
what kind of galaxy exhibits a large range of sizes/masses?
elliptical
Which of these would be made up of only Population II stars?
elliptical galaxies
what are the three types of galaxies?
elliptical, spiral, irregular
what happened in the inflationary epoch?
expansion. size of a proton -> size of a melon
T/F irregular galaxies are big
false
Spiral Galaxy/ Barred Spiral Galaxy
flat mix (Pop I) irregular in shape; mainly galaxies in collision
what are the characteristics of a disk?
flat, spiral arms, population I and II stars, interstellar gas/dust
Galactic Disk
flattened shape, spiral arms, both pop I and pop II stars, interstellar dust and gas, pop I stars associated with spiral arms
what happened in the grand unification epoch?
forces were unified
Shapely methods
globular clusters contain millions of stars, can be spotted at large distances and can help determine edge and center of galaxy
Self Propagating Stars
going super nova to make the next generation of stars
what is the oldest component of a galaxy?
halo
what makes up the space between galaxies in a cluster?
hot gas & dark matter
how many stars are in the milky way?
hundreds of billions (200 billion)
Rich Clusters
hundreds to thousands of galaxies large gravitational pull
what kind of galaxy has a lot of gas/dust?
irregular
what kind of galaxy has a lot of star production?
irregular
what kind of galaxy is made up of mainly population I stars?
irregular
Irregular Galaxy
largest percentage of population I and gas and dust other galaxies colliding with each other low mass high gas content and high star formation
Poor clusters
loosely held together, local group
Milky way
main sequence fitting
how do you determine position, or distance of the milky way?
main sequence fitting
Spiral Galaxy
mix of stars halo, bulge, galactic disk
what is the second rung on the distance ladder?
moon
Pop II
older stars, long life, little gas and dust in the area
Population II Stars
older stars, yellows and reds in color very little gas and dust
population II stars
older, yellow and red, long lifetime stars
Self-propagating star formation
one generation dies, new ones come; waves of stars; requires supernova explosions
Which property is common to spiral galaxies?
ongoing star formation and emission nebula in the arms
Poor Clusters
only a handful of galaxies, low mass, irregular in shape
Nearby stars
parallax
what is used to measure distance to nearby stars?
parallax
what epoch came first in the big bang?
planck epoch
what kind of cluster doesn't have as many galaxies in it?
poor
what kind of cluster has fewer galaxies because it has lower mass?
poor
what kind of cluster tends to be more irregularly shaped?
poor
Local Group
poor cluster milky way galaxy is a part of
what kind of star can you associate a spiral arm with?
population I
Elliptical Galaxy
population II stars low star formation, globular clusters, little gas or dust old stars, radial star motion
Pop II star
population of older stars, yellow and red, like globular clusters, with low metals, very little gas and dust.
Solar system
radar ranging
what is the first rung on the distance ladder?
radius of the earth
Elliptical Galaxy
random shaped
what was the distance ladder created for?
relate distances on a variety of scales
what kind of cluster has a lot of galaxies in it?
rich
what is the ninth rung on the distance ladder?
shape of the universe
Compared to our own Galaxy, elliptical galaxies
show no evidence of ongoing star formation.
what is the fifth rung on the distance ladder?
speed of light
what are the characteristics of a halo?
spherical, globular clusters, population II stars, little gas/dust
what kind of galaxy has a dense nucleus?
spiral
what kind of galaxy has an extended halo?
spiral
what kind of galaxy has spiral arms?
spiral
what kind of galaxy has a flattened disk?
spiral (also has spiral arms)
What is the shape of the milky way?
spiral galaxy
Spiral/Barred Galaxy
spiral galaxy in which a bar of material passes through the center of the galaxy, with the spiral arms beginning near the ends of the bar.
what is a barred spiral shape?
spiral galaxy with a central bar shape
what is the third rung on the distance ladder?
sun
where does a spiral arm originate?
the galaxy's center
Which is the oldest component of the Galaxy?
the halo
what is our galaxy?
the milky way
what is the density wave theory?
the stars move to denser regions but the spiral arms remain (greater mass density and increased pressure)
Density Wave Theory
traffic jam; cars = stars; stars move to denser regions; in and out, but spiral arm remains; young stars
T/F elliptical galaxies contain a lot of old stars
true
Galaxy clusters
tully fisher distant standards
what is the closest cluster to us?
virgo
what was the electroweak epoch?
weak and electromagnetic forces acting as one
what was the dark ages?
when atoms existed but stars did not
Clusters
where galaxies reside; MW is in the "local group" (a poor cluster); Rich clusters: Virgo cluster- big, a lot going on, giant elliptical galaxies
what kind of stars do elliptical galaxies have a lot of?
yellow pop II
was the inflationary epoch proven?
yes
what kind of stars do irregular galaxies have?
young blue stars
population I stars
young, bright blue, short lifetime stars
