What do you think of when you look at the night sky?...
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![Page 1: What do you think of when you look at the night sky? lada/ast3018/lectures/ast3018lecturestarform.pdf.](https://reader036.fdocuments.us/reader036/viewer/2022081513/56649e685503460f94b64e67/html5/thumbnails/1.jpg)
What do you think of when you look at the night sky?
http://www.astro.ufl.edu/~lada/ast3018/lectures/ast3018lecturestarform.pdf
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What is Space?• Not really empty• Stars, planets, etc.• Interstellar medium
• Dust and Gas• Nebulas
Orion Nebulahttp://hubblesite.org/gallery/album/nebula/pr1995044a/
Large Magellanic Cloudhttp://hubblesite.org/gallery/album/nebula/pr2006055a/
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Nebular Hypothesis
• Random collisions of atoms
• Areas of growing mass• Spherical shape• Pull in more matter• Increase in
• Temperature• Pressure
• Spin• Creates a bulge in the sphere
http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap06/FG06_17.jpg
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Nuclear Fusion
• High temperatures• 2 particles become 1• Releases a lot of energy• Video clip
• Particle accelerators• Man-made• Create new elements• Find smallest particles
Fermi National Labhttp://www.wired.com/playbook/2012/08/olympics-physics-hammer-throw/
http://www.universetoday.com/52696/nuclear-fusion-power-closer-to-reality-say-two-separate-teams/
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Spectroscopy Activity
•Draw the lines that you see• Make sure the # of lines, color of the lines and order is accurate
•Write a conclusion – based on your observations what can you conclude about the different materials and light you see the material produce
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Warm Up #1
•Clicker Quiz •Compare conclusions from the spectroscopy activity
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What does a spectrum tell us?• Each chemical/atom has a unique spectrum• Like a fingerprint
• What chemicals are present
http://www.umsl.edu/~physics/Lab%20Connection/Electricity%20and%20Magnetism%20Lab/12-lab13.html
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How is a spectrum created?• All objects emit light• Pure light from a source• Continuous spectrum
• If light passes through gas or dust• Light absorbed• Excites/heats atoms• Emit own light• Makes an emission spectrum
• Unique
https://www.cfa.harvard.edu/~jbattat/a35/cont_abs_em.html
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How do astronomers use spectra?• Look at light from
• Stars (gas in outer layers)• Nebula• Planets
• Determine chemical composition• Can also determine movement of object• Activity
http://www.eso.org/public/outreach/eduoff/cas/cas2004/casreports-2004/rep-236/
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Warm Up #2
•Why are emission spectra important?•How are emission spectrum created?•What 2 things can astronomers learn by looking at the spectrum from a star?
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H-R Diagram Graphing Activity
•Look for patterns
http://www.rootstown.sparcc.org/mattjust/h-r-diagram
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Color and Temperature• What did you see as a pattern?• Objects give off a variety of light• Peak depends on temperature
• Peak shows most common type of light
http://docs.kde.org/stable/en/kdeedu/kstars/ai-colorandtemp.html
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Main Sequence Stars• Find group on H-R
diagram• Wide variety• Highest # of stars• Stars stay here the
longest• Actively fusing hydrogen
into helium• Outward pressure from
fusion• Inward pressure from
gravity• Equal in these stars• Maintain size
http://www.rootstown.sparcc.org/mattjust/h-r-diagram
http://www.thenakedscientists.com/HTML/articles/article/the-science-of-the-supernova/
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What happens to our Sun?
• Form red giants• Fusing helium• Core collapsing• Outer layers
spread out• Cools
http://flightline.highline.edu/iglozman/classes/astronotes/media/2paths.jpg
http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/StarLife/Page7.html
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What then?• Forms a white dwarf
• Ran out of helium• No more fusion
• Outer gasses moving away• Planetary nebula
• Leaves a hot, dense corehttp://chandra.harvard.edu/xray_sources/white_dwarfs.html
Ring Nebulahttp://hubblesite.org/gallery/album/nebula/planetary/pr2004032d/
Cat’s Eye Nebulahttp://hubblesite.org/gallery/album/nebula/planetary/pr2004027a/
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Warm Up #3
•What makes a star a main sequence star?
•Why does the size of the core of a main sequence star not change?
•What will eventually happen to our Sun and why?
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What about the fate of larger stars?• Become red supergiants
• Fuse elements larger than helium• All the way to iron
• Short lives
• Supernova• No more fusion• Core violently explodes• Fuses heavier atoms• Very bright, short time• Spreads out material
http://flightline.highline.edu/iglozman/classes/astronotes/media/2paths.jpg
http://hubblesite.org/gallery/album/nebula/supernova_remnant/pr2005037a/
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What then?
• Forms a neutron star• If a lower mass core• Very dense
• Not very big• Lots of gravity
• Can produce gamma and x-rays when it pulls items into it
Neutron star in supernova Cassiopeia Ahttp://www.space-pictures.com/view/pictures-of-space/pictures-of-stars/neutron-star/index.php
http://www.clccharter.org/maya1/Supernova/supernova.html
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Or…• Forms a black hole
• Higher mass cores• Infinitely dense• Need to travel faster than the speed
of light to escape
• How can we see?• Will bend light from nearby stars• See dust and gas swirling around
• Hot enough to give off x-rays
• Probably at the center of most galaxies• Including ours!
• Video
Whirlpool Galaxyhttp://hubblesite.org/gallery/album/pr2001010a/
http://www.space.com/15421-black-holes-facts-formation-discovery-sdcmp.html
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Warm Up #4
• What is happening inside a red supergiant star?
• What happens in a supernova?• How is a neutron star different from a black hole?
• Why should we not be able to see a black hole?
• Why can we “see” a black hole?
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Warm Up #5
•Clicker Quiz
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Metric System Olympics
• Create a data table to organize the following items (one per group)• You will be doing the following “events” – paper plate “discus”, straw “javelin” and long jump
• For each “event” you will need a measurement, then you will change that measurement to another unit, and you will write this last unit in scientific notation
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How do we know how far away that is?• Parallax effect
• Compare distant stars to nearby stars
• Measure shift as Earth orbits the Sun
• Calculate the distance
• Further away = less of a shift
• Better technology = see smaller shifts = measure larger distances
http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT301/HTML/AT30105.HTM
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http://astronomy.nmsu.edu/aruiter/ASTRONOMY110/parallax.gif
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Looking Back in Time• If a star is 10 light years
away• How old is the light we see
today?• Is that star still there
today?
• If an alien is on a planet 10 million light years away• If they could see with the
Earth with great detail, what would they see right now?
• When we observe light from a star 2 billion light years away….what does that mean?
http://www.spacetelescope.org/images/heic1214c/
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How has our “picture” of the universe changed?
• Greeks• Rotating spheres
• Earth centered
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Early Scientists
•Galileo•Copernicus•Kepler•Newton
• Mathematical laws about movement of planets
• First telescope• Calculation of gravity
• Sun centered universe
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Next generation of scientists…• Einstein
• Calculations• Universe changing size• Disbelieved
• Added a constant to his equations
• Results = static universe
• Friedmann• Russian• Removed Einstein’s constant• Universe changing shape• Won Einstein’s approval
http://wouterdeheij.wordpress.com/2013/04/27/famous-innovation-quotes-from-steve-jobs-gunter-pauli-einstein-henry-ford-and-many-others/
http://en.wikipedia.org/wiki/File:Aleksandr_Fridman.png
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The Big Bang Theory
• Lemaitre• Priest and physicist• Universe began as a
single point• Expanded since that time
• Hubble• Astronomer• Published around same
time• Provided evidence
http://scienceblogs.com/startswithabang/2011/01/05/q-a-how-is-the-universe-so-big/
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Hubble’s Evidence - Redshift• Change in emission spectrum
• Same pattern• Shifted from where it should be
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Same thing happens with sound…• Doppler effect• Object moving past a stationary object• Waves get shortened in front
• Higher pitch
• Waves get longer in back• Lower pitch
• Inside the source – no change
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http://archive.ncsa.illinois.edu/Cyberia/Bima/doppler.html
Relating back to light…• Blue-shift
• Wavelength shortens• Moving towards us
• Red-shift• Wavelength lengthens• Moving away from us• Bigger the shift the further
away it has come from• Hubble only saw red-shifted
spectra
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Hubble’s Conclusions• Universe
moving away from us
• Things further away are moving away faster
• Expansion rate has
since beginning
https://www.e-education.psu.edu/astro801/book/export/html/1967
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Warm Up #6