Surveying-II SURVEYING-II. Surveying-II Horizontal Alignment.
Surveying the Stars Insert TCP 5e Chapter 15 Opener.
-
Upload
kerrie-daniels -
Category
Documents
-
view
217 -
download
2
Transcript of Surveying the Stars Insert TCP 5e Chapter 15 Opener.
![Page 1: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/1.jpg)
Surveying the Stars
Insert TCP 5e Chapter 15 Opener
![Page 2: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/2.jpg)
Properties of Stars
Our goals for learning:
• How do we measure stellar luminosities?
• How do we measure stellar temperatures?
• How do we measure stellar masses?
![Page 3: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/3.jpg)
How do we measure stellar luminosities?
![Page 4: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/4.jpg)
The brightness of a star depends on both distance and luminosity
![Page 5: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/5.jpg)
Luminosity:
Amount of power a star radiates
(energy per second = watts)
Apparent brightness:
Amount of starlight that reaches Earth
(energy per second per square meter)
Insert TCP 5e Figure 15.1
![Page 6: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/6.jpg)
Thought Question
These two stars have about the same luminosity -- which one appears brighter?
A. Alpha CentauriB. The Sun
![Page 7: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/7.jpg)
Thought Question
These two stars have about the same luminosity -- which one appears brighter?
A. Alpha CentauriB. The Sun
![Page 8: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/8.jpg)
So how far are these stars?
![Page 9: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/9.jpg)
Parallaxis the apparent shift in position of a nearby object against a background of more distant objects
![Page 10: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/10.jpg)
Parallax angle depends on distance
![Page 11: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/11.jpg)
Most luminous stars:
106 LSun
Least luminous stars:
10-4 LSun
(LSun is luminosity of Sun)
![Page 12: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/12.jpg)
How do we measure stellar temperatures?
![Page 13: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/13.jpg)
Every object emits thermal radiation with a spectrum that depends on its temperature
![Page 14: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/14.jpg)
An object of fixed size grows more luminous as its temperature rises
![Page 15: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/15.jpg)
Properties of Thermal Radiation1. Hotter objects emit more light per unit area at all
frequencies.
2. Hotter objects emit photons with a higher average energy.
![Page 16: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/16.jpg)
Hottest stars:
50,000 K
Coolest stars:
3,000 K
(Sun’s surface is 5,800 K)
![Page 17: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/17.jpg)
Solid
Molecules
Neutral Gas
IonizedGas(Plasma)
Level of ionization also reveals a star’s temperature
10 K
102 K
103 K
104 K
105 K
106 K
![Page 18: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/18.jpg)
Absorption lines in star’s spectrum tell us ionization level
![Page 19: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/19.jpg)
Lines in a star’s spectrum correspond to a spectral type that reveals its temperature
(Hottest) O B A F G K M (Coolest)
![Page 20: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/20.jpg)
(Hottest) O B A F G K M (Coolest)
Remembering Spectral Types
“Oh, Be A Fine Girl, Kiss Me”
![Page 21: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/21.jpg)
Thought Question
Which kind of star is hottest?
A. M starB. F starC. A starD. K star
![Page 22: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/22.jpg)
Thought Question
Which kind of star is hottest?
A. M starB. F starC. A starD. K star
![Page 23: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/23.jpg)
How do we measure stellar masses?
The orbit of a binary star system depends on strength of gravity
![Page 24: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/24.jpg)
Types of Binary Star Systems
• Visual Binary
• Eclipsing Binary
• Spectroscopic Binary
About half of all stars are in binary systems
![Page 25: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/25.jpg)
Visual Binary
We can directly observe the orbital motions of these stars
![Page 26: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/26.jpg)
Eclipsing Binary
We can measure periodic eclipses
![Page 27: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/27.jpg)
Spectroscopic Binary
We determine the orbit by measuring Doppler shifts
![Page 28: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/28.jpg)
We measure mass using gravity
Direct mass measurements are possible only for stars in binary star systems
p = period
a = average separation
p2 = a3 4π2
G (M1 + M2)
![Page 29: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/29.jpg)
Most massive stars:
100 MSun
Least massive stars:
0.08 MSun
(MSun is the mass of the Sun)
![Page 30: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/30.jpg)
What have we learned?
• How do we measure stellar luminosities?– If we measure a star’s apparent brightness and
distance, we can compute its luminosity with the inverse square law for light
– Parallax tells us distances to the nearest stars
• How do we measure stellar temperatures?– A star’s color and spectral type both reflect its
temperature
![Page 31: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/31.jpg)
What have we learned?
• How do we measure stellar masses?– Newton’s version of Kepler’s third law tells us
the total mass of a binary system, if we can measure the orbital period (p) and average orbital separation of the system (a)
![Page 32: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/32.jpg)
Patterns Among Stars
Our goals for learning:
• What is a Hertzsprung-Russell diagram?
• What is the significance of the main sequence?
• What are giants, supergiants, and white dwarfs?
• Why do the properties of some stars vary?
![Page 33: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/33.jpg)
What is a Hertzsprung-Russell diagram?
![Page 34: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/34.jpg)
Temperature
Lu
min
osi
tyAn H-R diagram plots the luminosity and temperature of stars
![Page 35: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/35.jpg)
![Page 36: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/36.jpg)
Most stars fall somewhere on the main sequence of the H-R diagram
Main Sequence
![Page 37: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/37.jpg)
Stars with lower T and higher L than main-sequence stars must have larger radii:
giants and supergiants
Large radius
Main Sequence
![Page 38: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/38.jpg)
Small radius
Stars with higher T and lower L than main-sequence stars must have smaller radii:
white dwarfs
Main Sequence
![Page 39: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/39.jpg)
A star’s full classification includes spectral type (line identities) and luminosity class (line shapes, related to the size of the star):
I - supergiantII - bright giantIII - giantIV - subgiantV - main sequence
Examples: Sun - G2 VSirius - A1 VProxima Centauri - M5.5 VBetelgeuse - M2 I
![Page 40: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/40.jpg)
Temperature
Lu
min
osi
tyH-R diagram depicts:
Temperatur
e
Color
Spectral
Type
Luminosity
Radius
![Page 41: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/41.jpg)
Temperature
Lu
min
osi
ty
Which star is the hottest?
![Page 42: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/42.jpg)
Temperature
Lu
min
osi
ty
Which star is the hottest?
A
![Page 43: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/43.jpg)
Temperature
Lu
min
osi
ty
Which star is the most luminous?
![Page 44: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/44.jpg)
Temperature
Lu
min
osi
tyWhich star is the most luminous?
C
![Page 45: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/45.jpg)
Temperature
Lu
min
osi
tyWhich star is a main-sequence star?
![Page 46: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/46.jpg)
Temperature
Lu
min
osi
tyWhich star is a main-sequence star?
D
![Page 47: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/47.jpg)
Temperature
Lu
min
osi
tyWhich star has the largest radius?
![Page 48: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/48.jpg)
Temperature
Lu
min
osi
tyWhich star has the largest radius?
C
![Page 49: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/49.jpg)
What is the significance of the main sequence?
![Page 50: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/50.jpg)
Main-sequence stars are fusing hydrogen into helium in their cores like the Sun
Luminous main-sequence stars are hot (blue)
Less luminous ones are cooler (yellow or red)
![Page 51: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/51.jpg)
Mass measurements of main-sequence stars show that the hot, blue stars are much more massive than the cool, red ones
High-mass stars
Low-mass stars
![Page 52: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/52.jpg)
The mass of a normal, hydrogen-burning star determines its luminosity and spectral type!
High-mass stars
Low-mass stars
![Page 53: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/53.jpg)
Core pressure and temperature of a higher-mass star need to be larger in order to balance gravity
Higher core temperature boosts fusion rate, leading to larger luminosity
![Page 54: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/54.jpg)
Stellar Properties Review
Luminosity: from brightness and distance
10-4 LSun - 106 LSun
Temperature: from color and spectral type
3,000 K - 50,000 K
Mass: from period (p) and average separation (a) of binary-star orbit
0.08 MSun - 100 MSun
![Page 55: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/55.jpg)
Stellar Properties Review
Luminosity: from brightness and distance
10-4 LSun - 106 LSun
Temperature: from color and spectral type
3,000 K - 50,000 K
Mass: from period (p) and average separation (a) of binary-star orbit
0.08 MSun - 100 MSun
(0.08 MSun) (100 MSun)
(100 MSun)(0.08 MSun)
![Page 56: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/56.jpg)
Mass & Lifetime
Sun’s life expectancy: 10 billion years
![Page 57: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/57.jpg)
Mass & Lifetime
Sun’s life expectancy: 10 billion years
Until core hydrogen(10% of total) is used up
![Page 58: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/58.jpg)
Mass & Lifetime
Sun’s life expectancy: 10 billion years
Life expectancy of 10 MSun star:
10 times as much fuel, uses it 104 times as fast
10 million years ~ 10 billion years x 10 / 104
Until core hydrogen(10% of total) is used up
![Page 59: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/59.jpg)
Mass & Lifetime
Sun’s life expectancy: 10 billion years
Life expectancy of 10 MSun star:
10 times as much fuel, uses it 104 times as fast
10 million years ~ 10 billion years x 10 / 104
Life expectancy of 0.1 MSun star:
0.1 times as much fuel, uses it 0.01 times as fast
100 billion years ~ 10 billion years x 0.1 / 0.01
Until core hydrogen(10% of total) is used up
![Page 60: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/60.jpg)
Main-Sequence Star SummaryHigh Mass:
High Luminosity Short-Lived Large Radius Blue
Low Mass:
Low Luminosity Long-Lived Small Radius Red
![Page 61: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/61.jpg)
What are giants, supergiants, and white dwarfs?
![Page 62: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/62.jpg)
Sizes of Giants and Supergiants
![Page 63: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/63.jpg)
Off the Main Sequence
• Stellar properties depend on both mass and age: those that have finished fusing H to He in their cores are no longer on the main sequence
• All stars become larger and redder after exhausting their core hydrogen: giants and supergiants
• Most stars end up small and white after fusion has ceased: white dwarfs
![Page 64: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/64.jpg)
Temperature
Lu
min
osi
ty
Which star is most like our Sun?
A
B
C
D
![Page 65: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/65.jpg)
Temperature
Lu
min
osi
tyWhich star is most like our Sun?
B
A
B
C
D
![Page 66: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/66.jpg)
Temperature
Lu
min
osi
tyWhich of these stars will have changed the least 10 billion years from now?
A
B
C
D
![Page 67: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/67.jpg)
Temperature
Lu
min
osi
tyWhich of these stars will have changed the least 10 billion years from now?
C
A
B
C
D
![Page 68: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/68.jpg)
Temperature
Lu
min
osi
tyWhich of these stars can be no more than 10 million years old?
A
B
C
D
![Page 69: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/69.jpg)
Temperature
Lu
min
osi
tyWhich of these stars can be no more than 10 million years old?
A
A
B
C
D
![Page 70: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/70.jpg)
What have we learned?
• What is a Hertzsprung-Russell diagram?– An H-R diagram plots stellar luminosity of
stars versus surface temperature (or color or spectral type)
• What is the significance of the main sequence?– Normal stars that fuse H to He in their cores
fall on the main sequence of an H-R diagram– A star’s mass determines its position along the
main sequence (high-mass: luminous and blue; low-mass: faint and red)
![Page 71: Surveying the Stars Insert TCP 5e Chapter 15 Opener.](https://reader036.fdocuments.us/reader036/viewer/2022062422/56649e7a5503460f94b79de4/html5/thumbnails/71.jpg)
What have we learned?
• What are giants, supergiants, and white dwarfs?– All stars become larger and redder after core
hydrogen burning is exhausted: giants and supergiants
– Most stars end up as tiny white dwarfs after fusion has ceased