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Study Points• What are binary stars?
• Why are binary stars important?
• What is an open cluster of stars? Where are these generally
located? Give an example.
• What is a globular cluster? Where are these generally located?
• What is a galaxy?
• Briefly describe or sketch the Milky Way galaxy. How big is it? How
many stars are in it? Where are we in it? Are we nearer the center
or edge? Where are the stars you see at night in it? Where are
open clusters in it? Where are globular clusters in it?
• What is our nearest large neighbor galaxy?
• What is the Local Group? About how big is it?
• Do galaxies collide? What is a cluster of galaxies?
• When we see objects like stars or galaxies in pictures, are we
seeing them as they look now or in the past? Why?
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Stars• Binary Stars
• Open Star Clusters
• Globular Clusters
• Milky Way Galaxy
• Other Galaxies
• Colliding Galaxies
• The Local Group
• Galactic Clusters
Binary Stars
• Two stars orbiting each other*
• Very common
Binary Stars
• Important use –
Used to measure mass of stars*
(using Kepler’s Laws)
Binary Stars
• Three Main Ways to Find Them
– Visual – see with telescope
– Eclipsing – light dims periodically
– Spectroscopic – Doppler shifts in spectra
Visual binary – See with telescope
Visual binary – See with telescope
Visual binary – See with telescope
Mizar A double star, part of
Mizar quadruple system
http://www.skyandtelescope.com/astronomy-
blogs/explore-night-bob-king/mizar-a-fresh-
look-at-an-old-friend03252015/
Eclipsing binary – light dims periodically
Watch video:
http://www.eso.org/public/usa/videos/eso1311b/
Eclipsing binary – light dims periodically
This is also the most common way to find planets outside our
solar system.
What are these planets called?
Eclipsing binary – light dims periodically
This is also the most common way to find planets outside our
solar system.
What are these planets called?
Exoplanets
Watch videos: (last video watched in class, watch first 2 at home)
http://csep10.phys.utk.edu/astr162/lect/binaries/spectroscopic.html
or
http://www.unm.edu/~astro1/101lab/lab9/lab9_C1.html
or
https://www.youtube.com/watch?v=1kFFwHkxBiI&list=PLJistbn1hLkxuwLpuOHbt
PRJFETEgu1RO (best)
Spectroscopic binary – wobble in spectral lines
Open Star Clusters
• Few to a few thousand stars grouped by
gravity in the same region of space*
• No particular shape
• Generally younger stars
• Located in plane of galaxy*
• Example – Pleiades*
http://www.spitzer.caltech.edu/images/2396-sig05-023-Star-Clusters-Found-in-the-MIlky-Way
Open Star Clusters in the Milky Way
Pleiades
M45 3000 stars ~400 LY away
13 LY across Brown dwarfs too
PleiadesM45 3000 stars ~400 LY away
13 LY across Brown dwarfs too
M39 Cygnus Open Cluster800 LY away
M7 Scorpius Open Cluster
1000 LY away
25 LY across,
Perseus double cluster of
open star clusters
7000 LY away few hundred LY across
http://antwrp.gsfc.nasa.gov/apod/ap070314.html
M95 galaxy with many open star clusters
2 Open Star Clusters in Puppis ConstellationM46 (upper left) 5,400 ly , 300 million years old, a few hundred stars, 30 ly across
M47 (lower right) 1,600 ly. 80 million years old, 50 stars, 10 ly across.
http://antwrp.gsfc.nasa.gov/apod/ap070314.html
Globular Clusters
• ~100,000 stars*
• Spherical shape
• Generally older stars
• Surround the galaxy
• Out of galaxy plane*
M13 Great Globular Cluster
25,000 LY away, 150 LY across
12 billion yrs old
http://apod.nasa.gov/apod/ap120614.html
Galaxy• Very large collection of gas, dust and
stars orbiting a central mass*
• 200 billion 2 trillion galaxies in the
universe (updated Oct. 2016)
• Each has millions to billions of stars
http://www.universetoday.com/30305/how-many-galaxies-in-the-universe/
Some Study Points to Research
1. Briefly describe or sketch the Milky Way
galaxy.
2. How big is it? (diameter)
3. How many stars are in it?
4. Where are we in it? Are we nearer the
center or edge?
5. Where are the stars you see at night located
in the galaxy?
6. Where are open clusters in it?
7. Where are globular clusters in it?
Milky Way Galaxy• ~400 billion stars*
• ~100,000 LY across*
• Think fried egg shape
• Spiral with arms
• 13 billion years old
http://apod.nasa.gov/apod/ap140916.html
http://apod.nasa.gov/apod/ap141031.html
Our Night Sky*
Globular Clusters
Open Clusters
Globular Clusters
IR COBE
Milky Way - edge on
Milky Way
What we think the Milky Way looks like from
a distance
M100 56 MLY away
From a distance, the Milky Way might look like this
Scientific Drawing of the Milky Way
http://www.jpl.nasa.gov/news/news.php?release=2010-179
100,000 LY
NGC 7331 Spitzer 50 MLY away
Blue older stars
If this was the MW, where is Earth?*
100,000 LY
You are here
If this was the MW, where is Earth?*
Downtown
Milky Way
30,000 LY
Other galaxies• Various shapes and sizes
• Types
– Elliptical (spherical)
– Spiral
• Ordinary spiral (Sa)
• Barred spiral (Sb)
– Irregular
– Other
• Dwarf
http://www.astro.cornell.edu/academics/courses/astro201/galaxies/types.htm
Large Magellanic Cloud
NGC 1365 SB
M100 SA
M87
Other galaxies• Most common
– Elliptical
• Oldest
– Elliptical
• Youngest
– Irregular
http://www.astro.cornell.edu/academics/courses/astro201/galaxies/types.htm
Large Magellanic Cloud
NGC 1365 SB
M100 SA
M87
Ordinary Spiral Galaxies
Ordinary Spiral (Sa)
Whirlpool Galaxy M51
30 MLY away
60 KLY across
Ordinary Spiral Sa M33
Pinwheel or Triangulum Galaxy
3 MLY
Barred Spiral Needle Galaxy
NGC 4565
30 MLY away
100,000 LY across
240 globular clusters
In Coma Berenices Constellation
Barred Spiral Sculptor Galaxy
NGC 613
65 MLY
NGC 6946 Sc or Sab
10 MLY away
In Cepheus Constellation
Irregular
Large Magellanic Cloud – southern hemisphere
180,000 LY away 15,000 LY across
Irregular
NGC 1569 7 MLY Camelopardalis
Sb M31 Andromeda 2.5 MLY
1 trillion stars (3X MW)
Andromeda Galaxynearest large neighbor galaxy*
https://alchetron.com/Abd-al-Rahman-al-Sufi
Abd al-Rahman al-Sufi
first described
Andromeda Galaxy in
964AD
Do galaxies collide?*
YES!
Galaxies Collide
• Galactic collision simulation
• http://www.youtube.com/watch?v=Lru7F
od1Evg&feature=related
•
NGC 2207 and IC 2163 colliding, 80 MLY away
http://apod.nasa.gov/apod/ap041121.html
Stephen’s Quintet 300 MLY Pegasus
NGC 4676
The Mice 300 MLY
Coma Berenices
Tadpole Galaxy
420 MLY
Tail is 280,000 LY.
Intruder is 300 MLY behind galaxy in front.
Antennae galaxies (NGC 4308, 4309) 63 MLY
25,000 ly separation
1200 km/s through gas
Image: http://antwrp.gsfc.nasa.gov/apod/ap060412.html
Watch Animation (from last lecture):http://chandra.harvard.edu/photo/2006/a400/animations.html
Binary black holes merging
= Galaxies merging
Andromeda Galaxy has 2 nuclei from previous mergerhttp://antwrp.gsfc.nasa.gov/apod/ap061126.html
2 nuclei at center of Andromeda galaxyhttp://antwrp.gsfc.nasa.gov/apod/ap961011.html
Milky Way and Andromeda Galaxies are
on a collision course!Watch NASA video of MW and Andromeda Collision
http://vimeo.com/43694515
The Local Group*• ~50 members less than 4 million LY away
from Milky Way
• Milky Way, Andromeda Galaxy dominate
• 2.5 million LY to Andromeda Galaxy
Large and Small Magellanic Clouds
Southern Hemisphere
Triangulum Galaxy
Canis Major Dwarf Galaxy
Nearest neighbor
Canis Major Dwarf in red
Milky Way in blue
NGC 6712 Loses Stars into the Milky Way Halo
(Artist’s impression)
Source: European Southern Observatory
ESR PR Photo 06c/99 (18 Feb 1999)
Hercules, 650Mly Credit & Copyright: Jim Misti
(Misti Mountain Observatory)
Do galaxies cluster? YES!
Cluster of Galaxies = group of galaxies*
Seyfert Sextet
190 MLY
each < 35,000 LY
Virgo Cluster of Galaxies
Virgo Cluster of Galaxies
Coma Bernices Cluster
~500 MLY
Millions of LY to cross
Coma Berenices Cluster
320 MLY http://antwrp.gsfc.nasa.gov/apod/ap070531.html
Sloan + Spitzer (dwarfs, 1000s)
~3000
galaxies
Hubble sees galaxies galore
Hubble Ultra Deep Field, 2004http://spacetelescope.org/images/heic0406a/
Watch this video fly through http://spacetelescope.org/videos/heic0714g/
http://imgsrc.hubblesite.org/hvi/uploads/image_file/image_attachment/23664/web_print.j
pg
2012
5,500+
galaxies
http://hubblesite.org/video/22-cosmic-exploration-hubble-extreme-deep-field
When we see an image of a star or
galaxy, are we seeing it as it looks
now or in the past?*• In the past*
• How long ago?*
– That depends on the distance*
– Examples:*
• A Star 8 light years away: the light takes 8 years to
reach us.
– Civilization there sends us a signal and we respond. It
takes 16 years for them to receive our response after they
send a signal.
• A Galaxy 10 billion light years away: the light takes
10 billion years to reach us!
• Why?* because light takes time to travel*
Do clusters cluster?
Yes, Superclusters! These are galactic clusters
What is the large scale structure of the
universe?
What does that tell us about the origin and
future of the universe?
Stay tuned…more in the next lectures
Stars• Binary Stars
• Open Star Clusters
• Globular Clusters
• Milky Way Galaxy
• Other Galaxies
• Colliding Galaxies
• The Local Group
• Galactic Clusters
• Next Lecture – Hubble’s Law and
Galaxy Motion
Homework & Updates• Keep up with Study Points
• D2L Quiz 9-12 available; Quizzes 9-13 for Test 3
• Optional – watch:• Binary and Multiple Stars: Astronomy Crash Course #34
• Star Clusters: Astronomy Crash Course #35
• LAB – Test 1 Nov. 19 & 21 THIS WEEK, open notebook• Make sure your notebook is ready! Do any missed labs.
• Observations:• Astrophysics Lecture Due Dec. 3 (10 pts) Write report (Lecture done 10/10)• Planetarium Due Dec. 3 (10 pts) Go to a planetarium show (Field trip 10/3)• Astronomy News Evalution Due Dec. 10 (20 pts) Evaluate astronomy news• Sunset – Part 2 Due Dec. 10 (10 points) Take 2nd picture of sunset in same place
• Take picture about 4pm; sunsets about 4:40pm• Stargazing Due Dec. 17 (20 pts) Go stargazing & write report• Telescope Due Dec. 17 (20 pts) Look through a telescope
• Look at calendar options & weather• Moon Craters Due Dec. 17 (10 pts) Look at magnified moon craters
• Borrow binoculars from Lab room
• No lecture or lab on Tuesday, Nov. 26. Work on observations.
Optional – watch:•Binary and Multiple Stars: Astronomy Crash Course #34
•Star Clusters: Astronomy Crash Course #35
Calendar Summary• Tuesday, 11/26: No lecture or lab. Work on observations.
• Tuesday, 12/3: Hubble’s Law & Galaxies & pick up lab
notebooks in lecture
• Thursday, 12/5: Big Bang
• Tuesday, 12/10: Life in the Universe (optional Lab Test 2)
• Thursday, 12/12: Test 3 (60 multiple choice questions)– Based on last 8 lectures & 5 D2L quizzes 9-13
– Some questions from D2L quizzes
– Bring pencil, no calculator needed
– Optional Lab Test 2 during lab times
• Tuesday, 12/17: Final Test today & handback Test 3– Based on all 23 lectures & 13 D2L quizzes (the whole semester)
– Many questions from D2L quizzes
– Bring pencil & calculator if you have one (some in classroom for you)
– Remember lowest of 4 tests is dropped (Test 1, 2, 3, & Final).
– If you took 3 previous tests and are happy with your grade, then you
don’t have to take the Final Test. If you missed a previous test, you
must take the Final Test. If you are trying to increase your grade, take
the final to hopefully drop a different test. No Astronomy on 12/19.