Chapter 14: Measuring Galaxies BREAKING NEWS! Chapter 14 Reading - - PowerPoint PPT Presentation

▶
chapter 14 measuring galaxies
SMART_READER_LITE
LIVE PREVIEW

Chapter 14: Measuring Galaxies BREAKING NEWS! Chapter 14 Reading - - PowerPoint PPT Presentation

May 12, 2023 345 likes •904 views

Chapter 14: Measuring Galaxies BREAKING NEWS! Chapter 14 Reading Assignment due now! Gas cloud orbiting the SMBH in the center of Turn in extra credit planetarium and public our Galaxy over a half hour more evidence observing reports up

slide-1
SLIDE 1

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Chapter 14: Measuring Galaxies

1

Chapter 14 Reading Assignment due now! Turn in extra credit planetarium and public

  • bserving reports up front when complete

Midterm 2 next Friday!

https://www.nytimes.com/2018/10/30/science/black-hole-milky-way.html? action=click&module=Well&pgtype=Homepage&section=Science BREAKING NEWS! Gas cloud orbiting the SMBH in the center of

  • ur Galaxy over a half

hour — more evidence it must really be a black hole.

slide-2
SLIDE 2

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 2

Now on to Galaxies!

slide-3
SLIDE 3

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Classifying Galaxies

3

  • Groups of 2-4, one sheet per group
  • One person from each group raise your hand (so TAs can

efficiently pass out dead tree shavings)

  • First step: Once I display the 8 galaxies onscreen, begin!

What is the overall shape of the galaxy? Is it smooth or mottled? What else do you find notable about it?

  • When finished with Questions 1-4, display your ABCD

card so I know when you’re done.

slide-4
SLIDE 4

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 4

M110 NGC 1300 M81 M87

slide-5
SLIDE 5

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 5

NGC 4449 NGC 1232 Sombrero NGC 3628

slide-6
SLIDE 6

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Chapter 14: Measuring Galaxies

6

Midterm 2 in one week! No office hours today New Galaxy Zoo HW due on Wednesday Turn in extra credit planetarium and public

  • bserving reports up front when complete

https://apod.nasa.gov/apod/ap170510.html

slide-7
SLIDE 7

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

How did you classify the galaxies?

7

M110 NGC 1300 M81 M87 NGC 4449 NGC 1232 Sombrero NGC 3628

slide-8
SLIDE 8

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 8

Cen A NGC 4731

Question 5: Try to incorporate these into your classification. Where would they go?

slide-9
SLIDE 9

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

How did you classify the galaxies?

9

M110 NGC 1300 M81 M87 NGC 4449 NGC 1232 Sombrero NGC 3628

slide-10
SLIDE 10

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Hubble’s Classification Scheme: Tuning Fork Diagram

10

slide-11
SLIDE 11

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 11

slide-12
SLIDE 12

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Appearance depends on orientation…

12

slide-13
SLIDE 13

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

…and the motions of stars

13

Bulges and Ellipticals

slide-14
SLIDE 14

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 14

Disk and Spiral Galaxies Which type of galaxy (Disk or Elliptical) is our galaxy, the Milky Way? Why do you think so?

slide-15
SLIDE 15

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 15

Color vs stellar age

A) Older stars have bluer colors B) Older stars have redder colors C) Stellar colors do not depend on age

slide-16
SLIDE 16

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 16

Which galaxy is oldest?

A B C

Which galaxy is prettiest?

slide-17
SLIDE 17

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Why is there a connection between shape & stellar age?

17

Hint: it’s analogous to planets in star systems Stars form from gas — gas settles into a disk due to angular momentum conservation!

slide-18
SLIDE 18

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Spiral arms are density waves (like sound waves)

18

slide-19
SLIDE 19

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Galaxies are not isolated

19

slide-20
SLIDE 20

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 20

slide-21
SLIDE 21

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 21

https://www.youtube.com/watch?v=52k-VryS1hs

slide-22
SLIDE 22

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Chapter 14: Measuring Galaxies

22

Midterm 2 this Friday! New Galaxy Zoo HW due on Friday (but preferred by Wednesday) Turn in extra credit planetarium and public

  • bserving reports up front when complete

https://www.youtube.com/watch?v=52k-VryS1hs

slide-23
SLIDE 23

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 23

A) Total Mass B) Age of stars C) Environment D) All of the above

What is the dominant factor that determines a galaxies appearance?

slide-24
SLIDE 24

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

What are galaxies mostly made of?

24

A) Stars B) Stellar Remnants C) Gas D) Who knows?

slide-25
SLIDE 25

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

What are galaxies mostly made of?

25

slide-26
SLIDE 26

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Can estimate the mass of elliptical galaxies from its hot, X-ray emitting gas

26

slide-27
SLIDE 27

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

What is dark matter?

27

  • Most likely a new kind of matter

(but possibly a modification to general relativity)

  • Does not absorb or emit light
  • Interacts very weakly, except

through its gravity

  • WIMP or MACHO? Axion or

sterile neutrino?

slide-28
SLIDE 28

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Active Galactic Nuclei (AGN) <—> Supermassive Black Holes (SMBHs)

28

more or less all galaxies have an SMBH, and its mass is proportional to the mass of its bulge Cygnus A Galaxy (optical) Jets from its AGN (radio) M87 Centaurus A

slide-29
SLIDE 29

Fall 2018: Chapter 5 ASTR/PHYS 1060: The Universe

But how are galaxies moving?

29

slide-30
SLIDE 30

Fall 2018: Chapter 5 ASTR/PHYS 1060: The Universe

Doppler Shift of Light

30

λobserved − λemitted λemitted = ∨ c

Which spectrum is moving away from us the fastest?

A B C D

slide-31
SLIDE 31

Fall 2018: Chapter 5 ASTR/PHYS 1060: The Universe 31

Almost all galaxies are moving away from us.

λobserved − λemitted λemitted = ∨ c

slide-32
SLIDE 32

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

We live in an expanding “balloon universe”

32

slide-33
SLIDE 33

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Activity Instructions

33

  • Groups of 3-5 people
  • HAND IN ONE SHEET WITH ALL GROUP MEMBERS

NAMES

  • Materials: Balloon, String, Ruler (or any reference

length), Marker, [Stopwatch or clock]

  • Roles: Secretary, Balloon Blower, Measurer, Speaker,

[Time Keeper]

slide-34
SLIDE 34

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Chapter 14: Measuring Galaxies

34

Midterm 2 this Friday! Galaxy Zoo HW due Friday

  • Ch. 15 & 16 Reading Assignments due

Monday & Wednesday TA Office Hour Reviews in JFB 325 today and tomorrow https://apod.nasa.gov/apod/ap170510.html

slide-35
SLIDE 35

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Additional discussion questions

35

  • Was there anything special about your reference

galaxy? If you had picked a different reference galaxy, would the slope of your line be different?

  • Parts of your balloon may have expanded faster than
  • thers because they have more or less stretchy balloon
  • stuff. How is this similar to some places in the actual

universe?

slide-36
SLIDE 36

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

What are the spiral nebulae?

36

Harlow Shapley Herber Curtis The great debate of 1920

MW is whole Universe

  • Sun is in outer part of the MW
  • M31 would have to be at an insane

distance to be similar

  • we can see rotation in the Pinwheel
  • this one nova in M31 would have

been impossibly bright MW is one of many galaxies

  • Sun is at the center of MW
  • M31 has too many novae to be just

a galactic nebula

  • we see dust lanes in other nebulae,

like the MW’s

slide-37
SLIDE 37

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Edwin Hubble settles the debate

37

M31: Andromeda Galaxy

slide-38
SLIDE 38

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Hubble’s Law

38

slide-39
SLIDE 39

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Distance Ladder

39

slide-40
SLIDE 40

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 40

Parallax Spectroscopic Parallax Cepheid Variables Type Ia SNe

slide-41
SLIDE 41

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 41

slide-42
SLIDE 42

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe

Midterm 2 Highlight Tour

42

Emphasize on understanding concepts over memorizing details But, need to know what terms mean Example: Should know the inputs and outputs of the p-p chain, but not necessary to know the details of each step 25 multiple choice questions (3 pts each), similar to last time Several short answer questions (more this time, but still 25 pts total) TA-led reviews in office hours this afternoon and tomorrow

slide-43
SLIDE 43

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 43

Luminosity depends on Temperature AND Size Stellar Spectra: blackbody plus absorption lines

slide-44
SLIDE 44

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 44

Binary Stars: Doppler shift proportional to velocity, inversely proportional to relative mass

slide-45
SLIDE 45

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 45

H-R Diagram

slide-46
SLIDE 46

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 46

proton-proton chain burns H —> He, releasing neutrinos and positrons (gamma rays) Sun has distinct zones, half way through its 10 billion year lifespan

slide-47
SLIDE 47

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 47

Triple-alpha process, burns He —> C in Horizontal Branch phase

slide-48
SLIDE 48

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 48

slide-49
SLIDE 49

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 49

White Dwarf <—> electron degeneracy pressure

if mass exceeds Chandrasekhar limit (1.4 Msun)

slide-50
SLIDE 50

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 50

Massive stars burn up to Fe (iron) in its core, then go supernovae (Type II)

slide-51
SLIDE 51

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 51

Neutron Stars Black Holes

slide-52
SLIDE 52

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 52

slide-53
SLIDE 53

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 53

Galaxies seem to have more mass than we can see —> dark matter

slide-54
SLIDE 54

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 54

Hubble’s law demonstrates that the universe is expanding

slide-55
SLIDE 55

Fall 2018: Chapter 14 ASTR/PHYS 1060: The Universe 55

Parallax Spectroscopic Parallax Cepheid Variables Type Ia SNe