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Molecules in stellar atmospheres

Molecules in stellar atmospheres. Thomas Masseron ULB In collaboration with P. Neyskens , A . Jorissen , S. Van Eck, B.Plez , M. Godefroid , P.F. Coheur , R. Colin. Outline. Molecules in stellar atmospheres Making molecular linelists Applications Conclusions.

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Molecules in stellar atmospheres

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  1. Molecules in stellar atmospheres Thomas Masseron ULB In collaboration with P. Neyskens, A. Jorissen, S. Van Eck, B.Plez, M. Godefroid, P.F. Coheur, R. Colin

  2. Outline • Molecules in stellar atmospheres • Making molecular linelists • Applications • Conclusions

  3. Molecules in stellar spectra

  4. electronic transitions: Optical rotational transitions: mm vibrational transitions: IR

  5. Outline • Molecules in stellar atmospheres • Making molecular linelists • Applications • Conclusions

  6. Making molecular linelists I Coupling dedicated codes & lab+astro observations simulate rotational structure to determine the line positions from molecular constants (Pgopher) Calculate transition moment (LEVEL) Compute stellar spectrum with stellar radiative transfer code (MARCS+Turbospectrum) Identify new lines and merge with laboratory’s Derive new molecular constants (Pgopher)

  7. Making molecular linelists II Many more lines are observed in stellar spectra. Stellar spectra can be used to improve the molecular laboratory data a from faboratory data Zachwieja et al. (1995)

  8. Outline • Molecules in stellar atmospheres • Making molecular linelists • Applications • Conclusions

  9. CH CEMP star

  10. CH: predissociation lines Definition: transition involving a level above the dissociation limit or perturbed by an unbound state Transition lifetimes need to be included !

  11. C2 In collaboration with Bertrand Plez

  12. LaO-YO in S-stars… Without YO With YO In collaboration with Pieter Neyskens

  13. … CeO in Mira (?) and “?” In collaboration with Pieter Neyskens In collaboration with Pieter Neyskens

  14. Conclusions and perspectives • Determine abundances (C-rich stars, S-stars…) • Include other molecules (HCl, NH, MgH,TiH, SH, TiS, CS …) • Mine spectroscopic archives (ESO-POP, HERMES…) • Include Landé factors (spectropolarimetry) Molecules are present in many other astronomical objects such as ISM, DLA or QSOs, blend planet spectra . The information on molecules we can get from stellar spectra can be used for those (and reciprocally)

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