1. 3 - Stellar Spectra

3. Why a slit? No slit Slit

4. Sky Backgrounds and Telescope Nods star slit

5. Visual & Photographic & 2D Electronic Detectors 1D or “Compressed” 2D Electronic Detectors

6. Increasing T Catalog Names

7. ...also collisions with electrons...

8. Balmer Series & Balmer Jump IR UV Visual!

9. Old Photographic NEGATIVES that Defined Spectral Classification BLUE part of the visual spectrum....

11. Pressure Broadening & Pressure Ionization (Energy Level Perturbation & Changing Recombination Rate)

12. Modern Digital Spectra (from Silva & Cornell 1992, ApJS, 81, 865)

13. Near-IR Spectra (Rayner et al. 2009, PASP, 185, 289)

14. Near-IR Detail

15. Originally, classification was based on spectra at visible wavelengths, since that’s all that was available at the time!

16. Log L T Luminosity Classes V = Main Sequence

18. Spectral Resolution

19. Measuring Stars at Different λs – “ Alphabet Soup Photometry ” - UBVRIJHKLMNQ “ Standard ” Johnson System (and newer Bessell Cousins-Kron filters) Filterλ eff (μm)Δλ(μm) U0.360.07 B0.440.10 V0.550.09 R CK 0.640.16 R0.700.22 I CK 0.800.15 I0.900.24 J1.250.23 H1.650.29 K2.20.42 L3.50.57 M4.60.34 N106 Q195 edge originally set by detector – now by filter

20. JH K L M

22. Photometry of 4 dusty stars

23. Photometry & Stellar Magnitudes where const(λ) is set by the photometric system Relative brightnesses of 2 stars at a given λ:

24. The relative brightness of a star at 2 different λs:

30. For a collection of stars at the same distance from us, and T versus L diagram translates into a Color- Magnitude diagram. The magnitude can be either M or m without destroying this correspondence.

32. Beyond OBAFGKM S Stars - dominated by ZrO C/O~1, sometimes Tc present! ( 99 Tc has half-life of 2.1x10 5 yrs)

33. Carbon Stars C/O >1 R - C/O > 1bands of C 2, C 3, CH, CN, etc. N - C/O > 1 and s-process elements like Ba & Sr CH - Old stars with stronger CH

34. Brown Dwarfs

36. Brown Dwarf Spectral Classes M - Above 2000 K, TiO and VO dominate T=2000-2200 K, TiO condenses into solids CaTiO 3 in M, Ti 3 O 5 & Ti 2 O 3 in cooler objects L (“new”!) - TiO and VO gone T (“new”!) - CH 4 appears in “H” and “K” photometric bands (actually in “L” at M5, in “K” at L8, and in “H” at T0 - “The Goldilocks Problem”) Y (discovered in 2012) – NH 3 (H 2 O??)

37. L & T (brown dwarfs)

38. NOTE: Very Non-Planckian

39. HD189733b Hubble Data Swain et al. 2008 Exoplanet “Spectra”