1. R. S. RAM, J. S. A. BROOKE Department of Chemistry, University of York, Heslington, York YO10 5DD, UK. G. LI Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA D. W. SCHWENKE NASA Ames Research Center, Moffett Field, CA 94035-10000, USA and P. F. BERNATH 2 Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 USA

2. OUTLINE

3. Introduction

4. Interstellar CN Violet 0-0 Diffuse interstellar cloud absorption towards the star HD169454 Gredel et al. AA, 251, 625 (1991) See also, A. McKellar, PASP, 52, 187 (1940) [ 12 CN]/[ 13 CN]=38 T rot = 3 K (same temperature as the cosmic background radiation)

5. CN (3,0) (red) in translucent clouds Early-type stars Schmidt et al. MNRAS 431, 1795 (2013) WGB stars Adamczak & Lambert ApJ 765, 155 (2013)

6. A 2 П-X 2 Σ + (red system) 12 C 14 N: Ram et al., JMS 263, 82 (2010) 13 C 14 N: Ram et al., ApJ Suppl. Ser. 188, 500 (2010); JMS 274, 22 (2012) More than 60 bands with v´=0-22, v˝=0-12, were analyzed for both isotopologues [4000-22000 cm -1 ] Summary of Spectroscopic Studies 12 C 14 N: Ram et al., JMS 237, 22 (2006) 13 C 14 N: Ram et al., ApJ Suppl. Ser. 194, 34 (2011) More than 50 bands with v´=0-15, v˝=0-15 were analyzed [20000-29000 cm -1 ] B 2 Σ + -X 2 Σ + (violet system) 12 C 15 N: Colin & Bernath, JMS 273, 30 (2012)

7. Lu, Huang, Halpern, ApJ 395, 710 (1992) Lifetimes of the A 2 Π state

8. Method of Calculation

10. Comparison of the A 2 Π state lifetimes (in μs)

11. Comparison of the B 2 Σ + state lifetimes (in ns)

16. Calculation of A v'v" and f v'v" values of the A 2 П-X 2 Σ + transition of CP Transition dipole moments Ram & Bernath, JMS 122, 282 (1987) Ram & Bernath, JMS 152, 89 (1992) Saito et al. ApJ 341, 1114 (1989) Klein et al. Z. Naturforsch 54a, 187 (1999) A 2 П-X 2 Σ + Measurements Microwave and THz measurements Brouckère & Feller, J. Phys. B 31, 5053 (1998) Intensity calculations for 75, A-X bands with v=0-8 levels of both states IRC+10216 Guélin et al. (1990) Cernicharo et al. (2000) Tenenbaum et al. (2007) B-X Herzberg (1930) B-A Bärwald et al. (1934)

20. CONCLUSION

21. ACKNOWLEDGMENTS LEVERHULME TRUST NASA LABORATORY ASTROPHYSICS PROGRAM NATIONAL SOLAR OBSERVATORY Thank you for your attention ! End

22. Astronomers classify stars by color using a series of letters: O, B, A, F, G, K and M. Under this classification, O stars are the hottest, and M stars are the coolest, with the other letters coming in between. O stars are “blue”, A stars are “white”, G stars are “yellow”, and M stars are red. Star Classification