groups of stars - mctcteach · 2020. 3. 27. · ngc 1365 sb m100 sa m87. elliptical galaxy. m87...

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

Elliptical Galaxy

M87 Virgo 50MLY

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

Sc M83

15 MLY

Hydra 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

8 BLY

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)

Perseus Cluster

300 MLY

~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.