K. Justtanont 1, J. Cami 2,3, T. de Jong 3,4, A.G.G.M. Tielens 5, & H. Feuchtgruber 6
1 Stockholm Observatory, 13336 Saltsjöbaden, Sweden SRON-Groningen, P.O. Box 800, 9700 AV Groningen, The Netherlands 2 University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3 SRON-Utrecht, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands Kapteyn Institute, P.O.Box 800, 9700 AV Groningen, The Netherlands
4 Max-Planck Institut für extraterrestrische Physik, Giessenbachstrasse, D-85740 Garching, Germany
We obtained a full grating scan of the semi-regular variable star W Hya. The high resolution spectrum makes it possible to identify the resposible species and hence model the absorption bands in the near infrared, with an aid of the Hitran database. Due to a resonably good signal-to-noise ratio, we are able to constrain the excitation temperature of each molecular absoprtion band. Relative abundances of molecules can then be calculated. A new molecule found in the spectrum of W Hya is identified tentatively as HCl.
W Hya also shows emission bands due to CO2. We have obtained Fabry-Perot spectrum centred at two of the emission band and also at absorption of the fundamental band. The relativele line strengths are then used to estimate the temperature. Preliminary estimate of the temperature is about 500K. We also investigate the question of the formation of CO2 via the reaction of CO + OH.