Astronomical Spectroscopy Introduction PMO David Haworth Copyright 2014

Transcription

1 Astronomical Spectroscopy Introduction PMO 2014 David Haworth Copyright 2014

2 Astronomical Spectroscopy Astrophysics Quantum Mechanics Electromagnetic spectrum provides insight to the universe Instrumentation Software 2

3 Astronomical Spectroscopy Analyzing Electromagnetic Spectrum Composition Spectra line patterns: atoms, ions & modules Temperature & density Spectra line patterns: atom states & transitions Stellar classification Motions Spectra line Doppler shift 3

4 Astronomical Spectroscopy Analyzing Electromagnetic Spectrum Abundance Spectra line strengths Pressure Spectra line profile Magnetic fields Spectra line splits 4

5 Electromagnetic Waves Credit c = c: speed of light (~ 3 x 10 8 meters/sec) : frequency (Hz) : wavelength (meters) Frequency increases ( ), wavelength decreases ( ) 5

6 Electromagnetic Waves Energy E: energy of a photon Credit E = h 1 electronvolt (1eV) = x Joules h: Planck s constant (6.626 x Joule seconds) : frequency (Hz) Frequency increases ( ), energy increases (E ) 6

7 Electromagnetic Waves Energy Credit Wavelength increases ( ), energy decreases (E ) UV IR λ nm λ Å E Joules ev E E E E E E E E E E E = h = c/ E = hc/ 1eV = x Joules 7

8 Electromagnetic Spectrum Credit 8

9 Wien s Displacement Law max = b/t 9 max : Peak emission at wavelength b: Wien's displacement constant m K T: temperature in Kelvin Kelvin = C F = (C 9/5) + 32 Kelvin C F Notes Absolute Zero Water Freezes Water Boils Draper Point Emits Red Emits White

10 Black Body Radiation Varying the power to a light bulb 10

11 Black-Body Radiation 7190 K & Peak at nm Credit 11

12 Black-Body Radiation 5730 K & Peak at nm Credit 12

13 Black-Body Radiation 4780 K & Peak at nm Credit 13

14 Spectrum of Light Continuous Spectrum 14 Credit astro.unl.edu

15 Spectral Lines of Light Hydrogen Emission Spectrum 15 Credit astro.unl.edu

16 Strong Spectral Lines of Hydrogen /PhysRefData /Handbook/Tables /hydrogentable2_a.htm 16

17 Strong Spectral Lines of Hydrogen NIST 17

18 Hydrogen Atom Energy Levels 18 Credit astro.unl.edu

19 Hydrogen Atom Energy Levels Credit 19

20 Continuous Spectrum Credit Star atmosphere, Nebula, etc. Star 20 Credit astro.unl.edu

21 Emission Spectrum Credit Star atmosphere, Nebula, etc. Star 21 Credit astro.unl.edu

22 Absorption Spectrum Credit Star atmosphere, Nebula, etc. Star 22 Credit astro.unl.edu

23 Hydrogen Absorption Spectrum Vega H-epsilon H-gamma H-alpha H-delta H-beta 23

24 Hydrogen Absorption Spectrum Denebola Spectrum H-gamma H-delta H-epsilon H-zeta H-beta 24

25 Hydrogen Absorption Spectrum Denebola Spectrum H-beta H-gamma H-delta H-alpha 25

26 Fraunhofer Solar Spectrum Lines Joseph von Fraunhofer ( ) 26 Credit

27 Fraunhofer Solar Spectrum Lines 27 Credit

28 Fraunhofer Solar Lines DVD Spectrograph F: H β b: Mg E: Fe D: Na G: Ca, Fe, H γ 28

29 Quantum Mechanics Lines Energy Levels Principal quantum number: n Angular momentum quantum number: l (sharp 0, principal 1, diffuse 2 or fundamental 3) Magnetic quantum number: m Same energy levels except in external magnetic fields. Spin quantum number: s Spin up (+ ½ ) or spin down (- ½ ) 29

30 Energy ev Na Double Lines Betelgeuse Lines Energy Levels 0 ev Ionization - Free electron l = 0 l = N = 3, l = 1, + ½ N = 3, l = 1, - ½ N = 3, l = 0, s = + ½ or + ½ 30

31 Early Astronomical Spectroscopy 1890: Harvard College Observatory 1890: 1 st Draper Memorial Catalogue 10,351 stars 1912: Last of the 4 Draper Memorial Catalogues 1922 IAU formal adoption of Draper system By temperature: OBAFGKM with decimal types 31 Credit

32 Star Classification Spectral Type = Star Temperature 32 Credit astro.unl.edu

33 Spectral Lines of Light Hydrogen Absorption Spectrum 33 Credit astro.unl.edu

34 Hertzsprung-Russell Diagram Luminosity vs. Temperature 34 Credit astro.unl.edu

35 Hertzsprung- Russell Diagram 22,000 stars from the Hipparcos Catalogue + 1,000 Low-lum. 35 Credit

36 Henry Draper Catalgues Astronomical Spectroscopy : Harvard College Observatory 225,300 stars Henry Draper (HD) Catalogue 46,850 stars Henry Draper Extension (HDE) 86,933 stars Henry Draper Extension Chart (HDEC) 36

37 Microsoft WorldWide Telescope Vega, Lyra 37

38 SIMBAD Vega A0V 38

39 Spectral Type Vega A0V 39 Credit

40 Luminosity Class Vega A0V 40 Credit

41 SIMBAD Vega, HD

42 VizieR Detail Page Vega, HD

43 VizieR Detail Page Vega, HD

44 Vega HD Sky Charts V2.76c 44

45 HD42088 O6V 45 Credit

46 HD A0V 46 Credit

47 HD G0V 47 Credit

48 HD95735 M2V 48 Credit

49 Astronomical Spectroscopy Analyzing Electromagnetic Spectrum Composition Spectra line patterns: atoms, ions & modules Temperature & density Spectra line patterns: atom states & transitions Stellar classification Motions Spectra line Doppler shift 49

50 Radial Velocity Spectra Credit 50 Credit astro.unl.edu

51 Radial Velocity Spectra Credit Quasar 3C 273 Redshift Measurement

52 Quasar 3C 273 Redshift Credit One 300 second image 3C

53 Quasar 3C 273 Redshift Credit 16 x 300 second images H-beta H-alpha 53 3C 273

54 Quasar 3C 273 Redshift Credit Star BD , F5 used for calibration H-beta H-gamma H-alpha BD C 273

55 Quasar 3C 273 Redshift Credit Redshift z =

56 Quasar 3C 273 Redshift Credit Observed Quasar 3C 273 Spectrum UV IR-A 56

57 Quasar 3C 273 Credit Observed Spectrum Redshift

58 58 M57 PMO 2014 Sunday Night

59 59 M57 PMO 2014 Sunday Night

60 60 M57 PMO 2014 Sunday Night

61 61 M57 PMO 2014 Sunday Night

62 Astronomical Spectroscopy Summary Analyzing Electromagnetic Spectrum Composition Spectra line patterns: atoms Temperature & density Spectra line patterns: atom states & transitions Stellar classification Motions Spectra line Doppler shift 62

63 63 Credits:

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