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- Astronomy Test 4
Astronomy Test 4
Astronomy Phy 1455 with Dwight at Baylor University
About this deck
By: Megan Mendez
Created: 2010-11-28
Size: 56 flashcards
Views: 118
Created: 2010-11-28
Size: 56 flashcards
Views: 118
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How many years does it take the sun to go around the Milky Way once?
230 million years
Sun's position in the Milky Way
- In the Disk
- 2/3 of the way out from the center
Halo
- Contains Globular Clusters
- Is spherical in shape
- Contains population II stars
- Very little interstellar gas and dust
Galactic Disk
- Flattened shape
- Spiral arms
- Both pop I and pop II stars
- Interstellar gas and dust
- Pop I stars associated with spiral arms
Bulge
- Center of the galaxy
- Football shape
- Pop II stars
- Little gas and dust
- Super massive black hole at the center
Shapely Method
- Determining the distance of globular clusters to determine the center of the Milky Way
- Our solar system is not at the center of the galaxy
Density wave theory for spiral arm formation
- Similar to a traffic jam
- Cars go in and out but the traffic jam remains but with different cars
- We will move in and out of spiral arms
- Clouds compress and form stars in the density wave, but only the fainter stars live long enough to make it out of the wave
Self Propagating star formation for spiral arm formation
- You have a row of firecrackers -- when you light one it causes the one next to it to explode, etc.
- When super massive stars explode (super nova explosion)
- they explode, produce new stars, explode, etc.
Population I stars
- Gas and Dust
- Young, Blue clusters
- Spiral arms and Galactic disk
- Seem to have order
- Orbit in and orderly fashion
Population II stars
- Random Motion
- Nuclear Bulge and Galactic bulge
- Older stars
- Very little gas and dust
Galaxies
Begin as spirals and through collision form into elliptical
Elliptical galaxy
- No structure --blob of irregular forming stars
- Mainly pop II stars
- Random orbit - no order
- little gas and dust
Spiral galaxy
- Spirals
- Flat
- Structured
- Orbit of stars in galactic disk have order
- Population I and II stars
- Flattened galaxy with a disk and a central bulge
Irregular galaxy
- Most Population I stars
- Blue-ish
- A galaxy with no definite structure
- most have a lot of gas and dust
- galaxies that don't fit into any regular shape
Rich Clusters
- Cluster of hundreds to thousands of (many) galaxies
- Closest Rich Cluster -- Virgo Cluster
- Super massive elliptical galaxies
Poor Clusters
- Galaxy cluster with only a few tens of galaxies
- We are part of a poor cluster -- Local Group
Local Group
Milky Way is a part of a poor cluster called the Local Group
Virgo Cluster
- Closest large cluster
- Called Virgo Cluster because it is in the direction of the Virgo Constellation
- Total mass of Virgo Cluster is large enough that its gravity pulls nearby groups of galaxies -- including the local group toward it
Planck Epoch
- A mystery partly because we lack a quantum theory of gravity
- Nothing is certain without a quantum theory of gravity
The Grand Unification epoch
- Forces except gravity are unified
- As temp rises the forces begin to behave in the same way and at this time they were indistinguishable between another
The Inflationary epoch
- Universe expands rapidly form smaller than a proton to bigger than a melon
- Supported experimentally
- Big Bang was NOT an explosion but expansions
Inflation and Cosmic Background Radiation
- Inflation gave rise to the density fluctuations --allowed stars and galaxies to form (denser areas)
- Density fluctuations is evident in Cosmic Background Radiation
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
- Quarks (basic building blocks) to hot and full of energy so they drift along by themselves
- Universe begins to cool --they begin to form together and produce Hadrons (protons and neutrons) and leptons (electrons)
Difference between Hadrons and Leptons
Hadrons fuel a strong nuclear force and Leptons do not
Leptons do not bind with other particles
Photons, Nucleosynthesis and Cosmic Background Radiation
- Atoms from hydrogen and helium and background radiation 'decouples' from matter
- Universe still cooling and floating proton, neutrons, and electrons begin to form atomic nuclei
- Big Bang Nucleosynthesis - the production of hydrogen and helium
- Cosmic Background Radiation - strongest piece of evidence of the Big Bang theory
Dark Ages
Atoms exists but stars do NOT
Gravity after the dark ages
- Gravity pretty much took over after the dark ages
- Gravity got the stars and galaxies to form
Modern Era
- Stars Form
- Cosmic Radiation Background is supporting evidence that stars and galaxies can later exist/form because there are denser and not so denser areas mapped by the longer microwave wavelengths
- Quantum fluctuations determine the distribution of matter
- denser areas - where stars form
Heavier elements formed from
supernova explosions
The defining feature of an epoch is..
temperature; as the universe expands it cools
Milky Way
- 100,000 light years across (diameter)
- About 200 billion stars
What is the name of our galaxy and what kind is it?
- Milky Way
- Barred Spiral
- 200 billion stars in our galaxy
- 100,00 light years across
- 2/3's of the way out in our galaxy -- in galactic disk
How do we determine our location?
Shapely Method
Where are OLD stars found
Halo and Center
Where are NEW stars found
Disk and Spiral Arms
What separates a cluster of stars from a galaxy
Galaxy: very large cluster of stars
Cluster: cluster of galaxies
What are four basic distinguishing characteristics between a spiral galaxy and an elliptical galaxy
- Shape
- Type of population stars
- Orbit
- Material contained
- More orderly
- Some or a lot of gas and dust
- Can have new star formation occurring in the disk; particularly in spiral structure
- Spiral structure
Cosmic Distance Ladder - Order form Closest to Farthest
- Radar ranging
- Parallax
- Main-sequence fitting
- Cepheids
- Distant standards
- Hubble's law
Radar Ranging
Solar System
10-4 light years
Parallax
Nearby stars
102 light years
Main-Sequence Fitting
Milky Way
105 light years
Cepheids
Nearby Galaxies
107 light years
Distant Standards
Galaxy clusters
1010 light years
White dwarf supernovae
Tully-Fisher relation
Spiral Arms
- Star formation occurs in the spiral arms because the gas clouds are compressed in the arms to form stars
- The spiral arms are where the stars pile up as they orbit the center
Nearest Galaxy to ours
Andromeda
it is part of our local group
Interstellar medium
the stuff between the Milky Way and galaxies
Spiral/Barred Spiral
More orderly motion
circular orbits
best mix of pop I and II stars
tend to have flat disks
What are four basic component of our galaxy
Galactic Disk
Halo
Nuclear Bulge
Super Massive black hole
How does density wave theory explain why stars form in spiral arms
Density wave theory says that stars get stuck in the dense part of the spiral arms
How does the self-propagating star formation theory explain why stars form
Self propagating theory says the explosions of supernovas triggers more explosions in the spiral arms
How do astronomers know that there is a very massive black hole at the center of the galaxy
they can observe stars orbiting it
Why are Irregular galaxies called irregulars
because they don't fit into any regular shape and have no consistent shape
Why do you see more galaxies when you look in a direction perpendicular to the galactic plane
along the galactic plane the galaxy blocks our view
Big Bang Epochs --From beginning to end
Planck epoch
Grand unification
Inflationary
Electroweak
Quark, Hadrons, Lepton epoch
Photon, Nulceosynthesis and Cosmic Background Radiation
Dark ages
Modern Era
Pretty Girls In EveningWear
Queens Pick Dick Munchers
About this deck
By: Megan Mendez
Created: 2010-11-28
Size: 56 flashcards
Views: 118
Created: 2010-11-28
Size: 56 flashcards
Views: 118
About StudyBlue
STUDYBLUE makes things that make you better at school.
Things like online flashcards with photos and audio.
Things like personalized quizzes and friendly reminders about when (and what) to study next.
Think of it as a digital backpack™: access to all of your study materials online and on your phone.
STUDYBLUE exists to make studying efficient and effective for every student, for free. Join us.
“I have used this website for three exams, and I see a huge difference in my test results.”
Naj
Naj