Olivier Thizy S.A.S. May 23rd, Big Bear Lake --

Transcription

1 High Resolution Spectrography Olivier Thizy S.A.S. May 23rd, Big Bear Lake --

2 Menu... What is a spectrum? A little bit of theory Lhires III spectrograph Some Projects Conclusion

3 What is a «spectrum»? Slit Ponctual object (ex: star) Large object (ex: Sun)

4 2D / 1D? Extracting a spectrum is to extract a 1D profile from a 2D image. A simple cut is not enough (poor signal/noise ratio) Optimized spectrum extraction has been programmes in several softwares (L_OPT in IRIS)

5 Resolution? Low Resolution (150 grooves/mm) Here is a comparison between a low and high resolution of Vega. Low Resolution: Overall shape Planck profile High Resolution: Line profile (Voigt, gaussian, etc...) FWHM Equivalent Width High Resolution (2400 gr/mm)

6 Kirchhoff's Laws High pressure gas (liquide or solid), when heated, emit a continuous emission which contains all colours a continuous spectrum; 2 Low pressure gas at low temperature, when located between a continuous source and an observer, absorbs some colours (absortion line spectrum); 3 A low pressure gas at high temperature will emit only some colours (emission line spectrum).

7 Black body profile 1 Profil de Plank K Intensité K K K Longueur d'onde (angstroms)

8 Electro-magnetic spectrum...

9 Visible: a very small window! Source: Getting the measure of the stars (WA Cooper & EN Walker)

10 Information from the profile Stefan's law: Intensity (below the curve) = Constant * T4 Wien's law: λ max * Temperature = Constant (2900 µm.k) ==>Temperature = Colour!!! Visible domain = nm (4000A-7000A)

11 H-R diagram

12 2 Absorption lines Solar spectrum is like the one of a black body (Teff=6000K) Solar atmosphere, cooler, absorbs some wavelength

13 2 Absorption lines Photosphere is very thin Line wings are coming from deeper than the center D'après:

14 2 Source: Tintin, the shooting star Absorption lines

15 Emission lines 3 Calibration/spectral lamp (here: internal Lhires III Neon lamp) are emitting emission lines.

16 fente Emission lines Diffuse and planetary nebulae are showing emission lines

17 Theory Energy = h * ν = h *c / λ

18 Table of Elements

19 Relative intensity per element

20 Doppler Effect λ λ λ+ Universe expansion = red shift = c

21 In summary... Light soming from stars tell us about: their temperature [overall shape] their composition and physical conditions of ionisation & excitement (so temperature) [lines] quantitative chemical composition, pressure, gravity de l'étoile [line intensity] movements [Doppler effect] Radial velocity Rotation Expansion 21

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23 Specifications Littrow design High Resolution (λ/ λ of around Hα) Dispersion of 0.01nm (9µm camera) Optimized for f/8-f/12 telescopes Adaptable to most types of telescopes Universal for acquisition: CCD camera, Digital SLR, webcam... Mirror Slit for precise centering & guiding Compact (250mm x 200mm x 83mm) et light (1.6kg) Optional grating/support to adapt resolution to your project Visual on the sun (without telescope) for public show Can be used for Spectro-Heliography 23

24 Lhires III 24

25 Spectra Acquisition 25

26 2D spectra processing 1D o t D 2 From 26

27 1D spectra analysis 27

28 Order of magnitude 0.1 Å = 0.01 nm = 5km/sec Visible spectrum: Å ( nm) CCD sensitivity: Å ETCL simulator: T200mm, Lhires III (30µm slit), KAF0400, 1 h exposure, S/N=100 Depending on your observations, you will have to compromise between Resolution, Spectral Field, Limiting Magnitude, Signal/Noise and Exposure Time 28

29 Some projects... 1 Sodium in all its shape! 2 Visual solar spectrum 3 Low resolution solar spectrum 4 Spectro-Heliography 5 Stellar Spectra Classification - Low Res 6 Stellar Spectra Classification - High Res 7 Line profile 8 Nebulae spectra 9 Novae: expansion speed 10 Radial Velocities 11 Earth rotation... and solar mass! 12 Jupiter / Saturn rotation 13 Stellar rotation - V.sin (i) 14 Spectroscopic binaries 15 Herbig Ae/Be stars 16 Be Stars(pros-amateurs collaboration, BeSS database) 29

30 1 Sodium in all its shape! Salt Match Pickels! Sirius Sun Street lamp (c) C. Buil / Benoit Minster 30

31 2 Visual Solar Spectrum obs. (c) Robin Leadbeater 31

32 Olivier Thizy January 2007 Lhires III 300gr/mm; Digital Rebel / EOS300D Pic du Midi observatory (few atmosphere!) Hα Doublet du Sodium Triplet du Magnésium Hδ H/K (Calcium) Hβ 3 Low Resolution solar spectrum 32

33 4 Spectro-Heliography 33

34 5 Stellar spectra Low Res. A0 Be M5 C8 Lhires III (150gr/mm) Digital Rebel SLR 30 sec exp. no computer! 34

35 5 Spectral Classification Low Res. Source: Benjamin Mauclaire; Lhires III (150 gr/mm) + KAF

36 6 Spectral Classification High Res. Oh-Be-A-Fine-Girl-Kiss-Me Lhires III & DSLR Sequence around Calcium triplet & Paschen sequence. Temperature is cooler from top to bottom. Christian Buil 36

37 7 Line profiles 37

38 8 Nebulae Spectra Hα 6563 [OIII] 5007 Hβ 4861 [OIII] 4959 [NII] 6583 [NII] 6548 HeI 5876 Spectre de M42 - Lhires III (150gr/mm) + KAF1600 / Acquisition: Benjamin Mauclaire / Processing: Olivier Thizy Image of M42: Olivier Garde & Adrien Viciana (CALA) HeI

39 9 Novae: expansion speed V1280 Sco V4743 Sgr 50 Å 2500 km/s RS Oph 39

40 10 Radial Velocities Spectra of SAO104807, Altaïr, et SAO

41 11 Earth movement... and solar mass! T =2 2 T = a V 4 2 G m1 m2 a 3 July Terre a Sun V = 30 km/s (+6 pixels) m1 January V = -30 km/s (-6 pixels) Terre m2 41

42 12 Jupiter / Saturn rotation Ex. for Saturn: Shift = 7 pixels = 8,8 km/s Period of 10,6 h --> R = km body Shelyak!Instruments... Rings are turning as a(c)solid = c 42

43 13 Stellar Rotation: V.sin(i) v.sin(i) = 330km/s v.sin(i) = 0km/s 43

44 14 Spectroscopic Binaries beta Auriga 2 spectra 72h apart With 3rd Kepler law, we can get to mass ratio of the two stars! 57 Cyg (C. Buil) beta Aurigae over 3h... 44

45 15 Herbig Ae/Be stars C.Buil 45

46 15bis Variables! Source: Getting the measure of the stars (WA Cooper & EN Walker) 46

47 16 Be Stars COROT program Magnetism, Pulsations? Your measures can help! 47 Amateurs Professionals Collaboration

48 Want to go further? - Subscribe to Spectro-L discussion group: - Participate to meeting, star parties, training courses... - Play with software & tutorials - Contact me: olivier.thizy@shelyak.com Two conditions for a good start: Know your telescope Know your camera 48

49 Useful links ARAS portal: Spectro-L group: C. Buil: Iris / SPIris: VisualSpec: Audela: Prism: BeSS: Projet Corot: CDS Strasbourg ADS (articles)

50 Useful books Stars and their spectra; James B Kaler, Cambridge edition A must have in your library... Be careful: this book is dangerous! :-) Practical Amateur Astronomy; Springer edition. collective book a must have too! Spectroscopy, the key to the stars; Springer edition. Missing the practical side of the subject, but an excellent starting point on spectroscopy theory. Stellar Photospheres; David F. Gray, Cambridge edition Excellent detailed book on the subject.

51 Thank You... Build & Distributed by: Shelyak Instruments Tél.: