stellar atmospheres: motivation 1 stellar atmospheres: literature dimitri mihalas –stellar...
TRANSCRIPT
![Page 1: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/1.jpg)
Stellar Atmospheres: Motivation
1
Stellar Atmospheres: Literature
• Dimitri Mihalas– Stellar Atmospheres, W.H. Freeman, San Francisco
• Albrecht Unsöld– Physik der Sternatmosphären, Springer Verlag (in German)
• Rob Rutten– Lecture Notes Radiative Transfer in Stellar Atmospheres
http://www.fys.ruu.nl/~rutten/node20.html
![Page 2: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/2.jpg)
Stellar Atmospheres: Motivation
2
Why physics of stellar atmospheres?
Physics
Stellar atmospheres as laboratories
Plasma-, atomic-, and molecular physics, hydrodynamics, thermodynamics
Basic research
Technical application
Astronomy
Spectral analysis of stars
Structure and evolution of stars
Galaxy evolution
Evolution of the Universe
![Page 3: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/3.jpg)
Stellar Atmospheres: Motivation
3
Magnetic fields in white dwarfs and neutron stars
Shift of spectral lines with increasing field strength
![Page 4: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/4.jpg)
Stellar Atmospheres: Motivation
4
Hertzsprung Russell Diagram
L~R2 T4eff
100 R
1 R
=700000Km
0.01 R
4 1026 W
5800K
![Page 5: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/5.jpg)
Stellar Atmospheres: Motivation
5
Massive stars
![Page 6: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/6.jpg)
Stellar Atmospheres: Motivation
6
Chemical evolution of the Galaxy
Carretta et al. 2002, AJ 124, 481
![Page 7: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/7.jpg)
Stellar Atmospheres: Motivation
7
SN movie
![Page 8: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/8.jpg)
Stellar Atmospheres: Motivation
8
SN Ia
![Page 9: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/9.jpg)
Stellar Atmospheres: Motivation
9
SN Ia cosmology
M,
0 , 1
0.5, 0.5
1 , 0
1.5, -.5
0 , 0
1 , 0
2 , 0
Redshift z
![Page 10: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/10.jpg)
Stellar Atmospheres: Motivation
10
SN Ia Kosmologie
![Page 11: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/11.jpg)
Stellar Atmospheres: Motivation
11
Uranium-Thorium clock
![Page 12: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/12.jpg)
Stellar Atmospheres: Motivation
12
Stellar atmosphere – definition
• From outside visible, observable layers of the star • Layers from which radiation can escape into space
– Dimension
• Not stellar interior (optically thick)• No nebula, ISM, IGM, etc. (optically thin)
• But: chromospheres, coronae, stellar winds, accretion disks and planetary atmospheres are closely related topics
![Page 13: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/13.jpg)
Stellar Atmospheres: Motivation
13
Sonne
![Page 14: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/14.jpg)
Stellar Atmospheres: Motivation
14
Fraunhofer lines
![Page 15: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/15.jpg)
Stellar Atmospheres: Motivation
15
Spectrum - schematicallyIn
ten
sit
y
Wavelength / nm
![Page 16: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/16.jpg)
Stellar Atmospheres: Motivation
16
Spectrum formation
![Page 17: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/17.jpg)
Stellar Atmospheres: Motivation
17
Formation of absorption lines
Interior outerboundary
observer
continuum
line center
continuum
stellar atmosphere intensity
![Page 18: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/18.jpg)
Stellar Atmospheres: Motivation
18
Line formation / stellar spectral types
spectral line temperature structure
interior
f
lux
wavelength
temp
erature
depth / km
![Page 19: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/19.jpg)
Stellar Atmospheres: Motivation
19
The spectral types on the main sequence
O B A F G K M
O5
B4
O7
B6
A1
A5
A8
A9
F8
G2
G5
G8
A7
F3
![Page 20: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/20.jpg)
Stellar Atmospheres: Motivation
20
Die Spektraltypen der Hauptreihe
O B A F G K M F6
F8
G2
G5
G8
A7
F3
G6
G9
K4
K5
F8
G1
![Page 21: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/21.jpg)
Stellar Atmospheres: Motivation
21
Classification scheme
M9
L3
L5
L8
![Page 22: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/22.jpg)
Stellar Atmospheres: Motivation
22
Classification scheme
T dwarfs
![Page 23: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/23.jpg)
Stellar Atmospheres: Motivation
23
Stellar atmosphere – definition
• From outside visible, observable layers of the star • Layers from which radiation can escape into space
– Dimension
• Not stellar interior (optically thick)• No nebula, ISM, IGM, etc. (optically thin)
• But: chromospheres, coronae, stellar winds, accretion disks and planetary atmospheres are closely related topics
![Page 24: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/24.jpg)
Stellar Atmospheres: Motivation
24
Optical telescopes
Calar Alto (Spain)3.5m telescope
![Page 25: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/25.jpg)
Stellar Atmospheres: Motivation
25
Optical telescopes
ESO/VLT
![Page 26: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/26.jpg)
Stellar Atmospheres: Motivation
26
Why is it important?
UV / EUV observations
flux
flux
wavelength / Å
wavelength / Å
![Page 27: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/27.jpg)
Stellar Atmospheres: Motivation
27
UV/optical telescopes
HST
![Page 28: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/28.jpg)
Stellar Atmospheres: Motivation
28
X-ray telescopes
XMM
![Page 29: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/29.jpg)
Stellar Atmospheres: Motivation
29
Gamma-ray telescopes
INTEGRAL
![Page 30: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/30.jpg)
Stellar Atmospheres: Motivation
30
Infrared observatories
ISO
JWST
![Page 31: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/31.jpg)
Stellar Atmospheres: Motivation
31
Sub-mm telescopes
![Page 32: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/32.jpg)
Stellar Atmospheres: Motivation
33
Stellar atmosphere – definition
• From outside visible, observable layers of the star • Layers from which radiation can escape into space
– Dimension
• Not stellar interior (optically thick)• No nebula, ISM, IGM, etc. (optically thin)
• But: chromospheres, coronae, stellar winds, accretion disks and planetary atmospheres are closely related topics
![Page 33: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/33.jpg)
Stellar Atmospheres: Motivation
34
PN – NGC6751 - HST
![Page 34: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/34.jpg)
Stellar Atmospheres: Motivation
35
Planetary nebula spectrum
![Page 35: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/35.jpg)
Stellar Atmospheres: Motivation
36
ISM spectrum
![Page 36: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/36.jpg)
Stellar Atmospheres: Motivation
37
Quasar + IGM spectrum
![Page 37: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/37.jpg)
Stellar Atmospheres: Motivation
38
Stellar atmosphere – definition
• From outside visible, observable layers of the star • Layers from which radiation can escape into space
– Dimension
• Not stellar interior (optically thick)• No nebula, ISM, IGM, etc. (optically thin)
• But: chromospheres, coronae, stellar winds, accretion disks and planetary atmospheres are closely related topics
![Page 38: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/38.jpg)
Stellar Atmospheres: Motivation
39
Eta Carinae - HST
![Page 39: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/39.jpg)
Stellar Atmospheres: Motivation
40
Stellar wind spectrum
![Page 40: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/40.jpg)
Stellar Atmospheres: Motivation
41
Formation of wind spectrum (P Cygni line profiles)
![Page 41: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/41.jpg)
Stellar Atmospheres: Motivation
42
Stellar winds – P Cyg profiles
![Page 42: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/42.jpg)
Stellar Atmospheres: Motivation
43
Accretion disks
![Page 43: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/43.jpg)
Stellar Atmospheres: Motivation
44
AM CVn disk spectrum
models
![Page 44: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/44.jpg)
Stellar Atmospheres: Motivation
45
Temperature structure of an accretion disk
Distance from star [km]
He
igh
t [k
m]
![Page 45: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/45.jpg)
Stellar Atmospheres: Motivation
46
Planetary atmospheres
![Page 46: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/46.jpg)
Stellar Atmospheres: Motivation
47
Quantitative spectral analyses – what can we learn?
Shape of line profile:Temperature Film
Density Film
Abundance Film
Rotation
Turbulence
Magnetic field
Line position:Chemical composition
Velocities
Redshift
Temporal variation:Companion
Surface structure
Spots
Pulsation
![Page 47: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/47.jpg)
Stellar Atmospheres: Motivation
48
Zeeman effect
![Page 48: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/48.jpg)
Stellar Atmospheres: Motivation
49
Magnetic fieldsL
l
optical spectrum
circular polarization
position of line components
spectrum of a white dwarf (PG 1658+440) with fieldstrength of about 5 MG
![Page 49: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/49.jpg)
Stellar Atmospheres: Motivation
50
Magnetic fieldsL
White dwarf Grw+70 8247B=300MG
optical spectrum
Circular polarization
positionof line components
![Page 50: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/50.jpg)
Stellar Atmospheres: Motivation
52
Velocity fields
Wavelength / Å
Dis
tan
ce /
10
00 k
m
~ 0.01Å
Solar disk
time / min
dist
ance
/ 1
000k
m
![Page 51: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/51.jpg)
Stellar Atmospheres: Motivation
55
Time dependent line profilesT
ime
Flu
x
![Page 52: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/52.jpg)
Stellar Atmospheres: Motivation
56
Doppler tomography
![Page 53: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/53.jpg)
Stellar Atmospheres: Motivation
57
Summary – stellar atmospheres theory
The atmosphere of a star contains less than one billionth of its total mass, so, why do we care at all?
• The atmosphere of a star is that what we can see, measure, and analyze.• The stellar atmosphere is therefore the source of information in order to put a
star from the color-magnitude diagram (e.g. B-V,mv) of the observer into the HRD (L,Teff) of the theoretician and, hence, to drive the theory of stellar evolution.
• Atmosphere analyses reveal element abundances and show us results of cosmo-chemistry, starting from the earliest moments of the formation of the Universe.
• Hence, working with stellar atmospheres enables a test for big-bang theory.• Stars are the building blocks of galaxies. Our understanding of the most
distant (hence most early emerged) galaxies, which cannot be resolved in single stars, is not possible without knowledge of processes in atmospheres of single stars.
• Work on stellar atmospheres is a big challenge. The atmosphere is that region, where the transition between the thermodynamic equilibrium of the stellar interior into the empty blackness of space occurs. It is a region of extreme non-equilibrium states.
![Page 54: Stellar Atmospheres: Motivation 1 Stellar Atmospheres: Literature Dimitri Mihalas –Stellar Atmospheres, W.H. Freeman, San Francisco Albrecht Unsöld –Physik](https://reader035.vdocuments.us/reader035/viewer/2022062308/56649e0f5503460f94afa588/html5/thumbnails/54.jpg)
Stellar Atmospheres: Motivation
58
Summary – stellar atmospheres theory
Important source of information for many disciplines in astrophysics– research for pure knowledge, contribution to our culture– ambivalent applications (e.g. nuclear weapons)
Application of diverse disciplines– physics– numerical methods
Still a very active field of research, many unsolved problems– e.g. dynamical processes