Suzanne Bisschop

1. Suzanne Bisschop Jes Jørgensen, Ewine van Dishoeck, Evelyn de Wachter, Guido Fuchs, Harold Linnartz 17-08-07 Testing grain-surface chemistry in massive hot-core regions and the laboratory(A&A, 465, 913 and A&A submitted)

2. Origin of complex molecules in star-forming regions • Wealth of complex organic molecules detected in protostellar hot core regions (both high- and low- mass!) • Origin unclear: • Grain-surface chemistry • High temperature gas phase chemistry • Aim: test grain surface chemistry proposed by Tielens & Charnley through combined observations and lab experiments Based on Tielens and Charnley 1997 ---:detected in gas phase ––:detected in solid state

3. Observed JCMT spectra and correlations N(X)/bf Observed abundance relations and excitation temperatures used to classify molecules Some model relations confirmed, some not Empirical correlations H2CO CH3OH HNCO NH2CHO CH3OCHO Expected to form from CH3CHO, but precursor detected only in cold gas C2H5OH CH3OCH3 Bisschop et al., A&A, 465, 913

4. Testing the CH3CHO + H  C2H5OH reaction in the laboratory CH3CHO ices are bombarded at 10-10 mbar with H-atoms (flux: ~8x1013 atoms s-1) Yields of ~20% C2H5OH are detected with a QMS mass spectrometer! But CH4, H2CO and CH3OH are formed as well => fragmentation Bisschop et al., submitted to A&A

5. Conclusions Confirmed! • Experiments show that formation of C2H5OH from CH3CHO in the ice is possible • Remaining question: why is no CH3CHO observed in hot cores? • It is fully hydrogenated in the ice before desorption • It is destroyed in the ice by thermal/energetic processing Based on Tielens and Charnley 1997 Confirmed! Molecular line observations + laboratory experiments of interstellar ice analogues  toward understanding chemical processes in star forming regions ---:detected in gas phase ––:detected in solid state

6. Extra slides

7. Rotational temperatures . . H2CO CH3CN CH3OCH3 CH3OH C2H5CN NH2CHO Hot CH3CCH Cold

8. SURFRESIDE set-up Main QMS To rotary stage From FTIR Spectrometer 7:1 / 45:8 ellipsoidal mirror :18 off-axis parabolic mirror InSb / MCT l.N2 cooled IR detector To rotary stage Turbo Pump External link to FTIR Spectrometer gas Atomic Source Turbo Pump To rotary stage H2

9. Structure protostellar envelope Cold outer envelope: D~1017 cm T~40-60 K n(H2)~106 cm-3 ices gas Warm envelope: D~1016-1017 cm T~100-150 K n(H2)~106-107 cm-3 Hot core: D~1016 cm T~150-200 K n(H2)~107-108 cm-3 Based on Figure for G327.3 1 by Gibb et al. 2001, ApJ, 545, 309

10. Eley-Rideal Mechanism Langmuir - Hinshelwood Mechanism A2B B A2B A A2 A2 A2B diffusion AB AB A B Grain-surface processes Fraser et. al. A&G, 43, no. 2, 2.10 (2002)

11. NH4+ Ices toward low-mass protostars with Spitzer Silicate CH4 CO2 H2O Boogert, Pontoppidan, Oberg, Bottinelli et al. 2007

12. Spitzer observations of ices toward low-mass YSOs • - Large overall similarity with high-mass YSOs • - NH3, CH3OH detected in some sources with high abundances (10% of water) • - New lab data on HCOOH, CO2-CO, H2O-CO2, H2O-CO, NH3-H2O to interpret Spitzer spectra Boogert et al. 2004, Oberg et al. 2007, Bisschop et al. 2007 Fraser et al. 2007, Bouwman et al. 2007