Overview of Astronomy AST 200. Astronomy Nature designs the Experiment Nature designs the Experiment...
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Overview of Overview of Astronomy Astronomy AST 200 AST 200
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Transcript of Overview of Astronomy AST 200. Astronomy Nature designs the Experiment Nature designs the Experiment...
Overview of Overview of AstronomyAstronomy
AST 200AST 200
AstronomyAstronomy
Nature designs the ExperimentNature designs the Experiment ToolsTools
1)1) ImagingImaging
2)2) SpectroscopySpectroscopy
3)3) ComputationalComputational
Galaxy – Gravitationally Galaxy – Gravitationally bound aggregate ofbound aggregate of
Million to 100 billion starsMillion to 100 billion stars Gas and dust (10s of % by mass)Gas and dust (10s of % by mass) Dark MatterDark Matter
Properties…Properties… Masses = million to trillion solar massesMasses = million to trillion solar masses Sizes = 30,000 to 300,000 light yearsSizes = 30,000 to 300,000 light years Rotation Period = 10 – 100 million years Rotation Period = 10 – 100 million years Average Separation = 3 million light yearsAverage Separation = 3 million light years
Galaxy Types – Spiral Galaxy Types – Spiral GalaxiesGalaxies
Central Bulge – Old StarsCentral Bulge – Old Stars Disk – Young Stars, Gas, and DustDisk – Young Stars, Gas, and Dust Some have barsSome have bars
Schematic of Spiral Schematic of Spiral GalaxyGalaxy
The Sun is approximately 28,000 light years from the center of our Galaxy
Galaxy Types – Elliptical Galaxy Types – Elliptical GalaxiesGalaxies
Old StarsOld Stars Very little Gas Very little Gas and Dustand Dust
Galaxy Types – Dwarf Galaxy Types – Dwarf EllipticalsEllipticals
Masses = 10 Masses = 10 million to 1 million to 1 billion Solar billion Solar MassesMasses
There are a lot There are a lot more dwarf more dwarf elliptical elliptical galaxies than galaxies than there are spiral there are spiral or normal or normal elliptical elliptical galaxiesgalaxies
Galaxy Components - Galaxy Components - StarsStars Powered by fusion Powered by fusion
(hydrogen helium (hydrogen helium + energy)+ energy)
Stability – balance Stability – balance of inward gravity and of inward gravity and outward radiation outward radiation pressurepressure
Importance – heat, Importance – heat, light, metal light, metal productionproduction
Lots of low mass Lots of low mass stars, fewer high stars, fewer high mass stars, & the mass stars, & the relative fraction may relative fraction may be the same for every be the same for every star-forming star-forming environmentenvironment
QuickTime™ and aYUV420 codec decompressor
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Hertzsprung-Russell DiagramHertzsprung-Russell Diagram
Stars (cont)Stars (cont)
Lifetimes of Stars depend upon Lifetimes of Stars depend upon Mass (Sun = 10 billion years)Mass (Sun = 10 billion years)
End State Depends on MassEnd State Depends on Mass Average Separation of Stars 3 Average Separation of Stars 3 – 4 light years– 4 light years
End StatesEnd States MMstarstar < 8 M < 8 Msolarsolar - White dwarf - White dwarf
MMstarstar = 8-60 M = 8-60 Msolarsolar - Neutron star - Neutron star
MMstarstar > 60 M > 60 Msolarsolar - Black hole - Black hole
Evolution along the HR Evolution along the HR DiagramDiagram
Galaxy Components - Solar Galaxy Components - Solar SystemsSystems
Solar systems consists Solar systems consists of objects that are of objects that are gravitationally bound gravitationally bound to starsto stars
Our own solar system Our own solar system consists of 8 – 9 consists of 8 – 9 planets, comets, and a planets, comets, and a host of smaller objects host of smaller objects comprised of rock and comprised of rock and iceice
Many extrasolar planets Many extrasolar planets have been found have been found recently, indicating recently, indicating that solar systems may that solar systems may be quite commonbe quite common
Formation of Formation of SolarSolar SystemSystem
Products
Planets Comets, etc
Our Solar System: Terrestrial Our Solar System: Terrestrial & Gas Giants& Gas Giants
Formation of the Solar Formation of the Solar SystemSystem
QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.
Extrasolar Planets - Radial Extrasolar Planets - Radial VelocitiesVelocities
• Accuracy needed: ~10s of m s-1 or ~ 20 mph (Video)
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Examples -Examples -
Galaxy Components – GasGalaxy Components – Gas
Stars form in Stars form in molecular cloudsmolecular clouds
Molecular clouds Molecular clouds can have masses can have masses of up to 1 of up to 1 million solar million solar massesmasses
Molecular gas is Molecular gas is found in the disk found in the disk regions of spiral regions of spiral galaxiesgalaxies
Gas, cont.Gas, cont.
Neutral hydrogen Neutral hydrogen gas extends gas extends farther out in farther out in galaxies than galaxies than the stellar disk the stellar disk doesdoes
We use the We use the motion of the motion of the gas to determine gas to determine galaxy masses…galaxy masses…
… … and to trace and to trace interactioninteraction
Components – Black Components – Black HolesHoles
Very massive stars form black holes Very massive stars form black holes when they diewhen they die
But we also find supermassive But we also find supermassive (million to a billion solar masses) (million to a billion solar masses) black holes at the centers of black holes at the centers of galaxiesgalaxies
There is a relationship between the There is a relationship between the mass of black hole in the center of mass of black hole in the center of a galaxy and the mass of stars in a galaxy and the mass of stars in the bulge of a galaxythe bulge of a galaxy
The Center of Our The Center of Our GalaxyGalaxy
Dark MatterDark Matter It appears that most It appears that most (90%) of the mass in (90%) of the mass in the universe is dark the universe is dark – i.e., it doesn’t – i.e., it doesn’t emit lightemit light
Evidence – e.g., Evidence – e.g., masses calculated masses calculated from galaxy rotation from galaxy rotation curvescurves
Distribution in Distribution in galaxies – sphericalgalaxies – spherical
What is it? dead What is it? dead stars, black holes + stars, black holes + SOMETHING ELSESOMETHING ELSE
Starburst Galaxies & Starburst Galaxies & Active GalaxiesActive Galaxies
Some galaxies are Some galaxies are observed to be observed to be making new stars at making new stars at 10 – 100 times that 10 – 100 times that of normal spiral of normal spiral galaxiesgalaxies
Others are observed Others are observed to have bright, to have bright, compact nuclei compact nuclei which appear to be which appear to be powered by mass powered by mass accretion onto a accretion onto a central black holecentral black hole
We believe that activity in extreme We believe that activity in extreme starburst galaxies & active galaxies starburst galaxies & active galaxies are mostly caused by a galaxy merger are mostly caused by a galaxy merger
eventevent
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Clusters of GalaxiesClusters of Galaxies
Very massive – Very massive – 100 trillion 100 trillion solar massessolar masses
Cosmology – origin and Cosmology – origin and evolution of the universeevolution of the universe
The universe is The universe is expanding – all expanding – all galaxies are moving galaxies are moving away from usaway from us
The universe was The universe was once much hotter – once much hotter – 3K background 3K background radiationradiation
A lot of work has A lot of work has gone into finding gone into finding distant galaxies in distant galaxies in order to figure out order to figure out when the first when the first galaxies formed and galaxies formed and how they evolve.how they evolve.
Cosmology – origin and Cosmology – origin and evolution of the universeevolution of the universe
The universe is The universe is expanding – all expanding – all galaxies are moving galaxies are moving away from usaway from us
The universe was The universe was once much hotter – once much hotter – 3K background 3K background radiationradiation
A lot of work has A lot of work has gone into finding gone into finding distant galaxies in distant galaxies in order to figure out order to figure out when the first when the first galaxies formed and galaxies formed and how they evolve.how they evolve.
3K Cosmic MicrowaveBackground
Cosmology – origin and Cosmology – origin and evolution of the universeevolution of the universe
The universe is The universe is expanding – all expanding – all galaxies are moving galaxies are moving away from usaway from us
The universe was The universe was once much hotter – once much hotter – 3K background 3K background radiationradiation
A lot of work has A lot of work has gone into finding gone into finding distant galaxies in distant galaxies in order to figure out order to figure out when the first when the first galaxies formed and galaxies formed and how they evolve.how they evolve.
Cosmological ParametersCosmological Parameters
Hubble Constant = HHubble Constant = H00
Density of Universe = Density of Universe = mattermatter + + DMDM + +
