A Search for Interstellar H2DO+ Christopher P. Morong Department of Chemistry, University of Chicago Shuji Saito, Takashi Furuya Research Center for Development of Far-Infrared Region, Fukui University, Fukui, Japan Hiroko Shinnaga Caltech Submillimeter Observatory Takeshi Oka Department of Astronomy and Astrophysics, and Department of Chemistry, University of Chicago 63rd Ohio State University International Symposium on Molecular Spectroscopy

Why H2DO+? Galactic D/H~10-5 Special conditions deuterium fractionation >104 CO and N2 freeze onto grain surfaces NH3 and N2H+ survive in gas phase in highly depleted cores OH, H2O and H3O+ may also survive in gas phase If atomic oxygen does not stick efficiently to grain surfaces Probe of oxygen chemistry in clouds Less atmospheric interference

H2DO+ Formation * *Cold dense clouds

H2DO+ Experiment Stainless steel hollow-cathode 1.1 m long 2.4 Pa H2O + 1.6 Pa D2O 400 mA Tcell~240 K Isotopic, magnetic (ion/neutral) and temperature discrimination T. Furuya, S. Saito and M. Araki, J. Chem. Phys, 127, 244314 (2007)

H2DO+ Energy Levels ~ 60 K T. Furuya, S. Saito and M. Araki, J. Chem. Phys, 127, 244314 (2007)

H3O+ Transitions Phillips et al., Astrophysical. J. 399 (1992) 533

1.3 mm continuum Mott et al., A&A 336 (1998) 150-172 Huang et al., Adv. Space Research 36 (2005) 146-155

IRAS 16293-2422 ~120 pc from Earth in the  Ophiuchus cloud complex +4.0 km/s Protobinary system ~600 AU Inside L1689N Class 0 protostar Luminosity ~ 27 L Mass ~ 1.1 M Temperature ~ 20 - 100 K Density 104 - 107 cm-3 ~30,000 years collapsing 800-2500 years old (evaporation of the mantles) Wakelam et al. A&A 413 (2004) 609

IRAS 16293-2422 CH3OD 2% CH2DOH 30% HDO 3% HDCO 15% D2O 0.005% CHD2OH 6% D2CO 5% CD3OH 1.4% HCO+, CH3OCHO, CH3OCH3, HCOOH, CH3COOH, CH3CHO, CH3CN, CH3CCH, C2H5CN, SO, SO2, HCN, HNC, OCS, H2CS, CH2CDCN…

Caltech Submillimeter Observatory 10.4-m hexagonally-segmented Leighton dish Heterodyne SIS receivers 230, 345, 490 and 665 GHz atmospheric windows

Atmospheric Transmission

Observation Conditions

Results (19.17 minutes)

Future The search continues Hope for dry weather