%0 Journal Article
%T Missing water in Class I protostellar disks
%A A. D. Bosman
%A A. Ramos
%A D. Harsono
%A E. A. Bergin
%A E. F. van Dishoeck
%A J. C. Mottram
%A J. K. J£¿rgensen
%A L. E. Kristensen
%A L. T. Maud
%A M. R. Hogerheijde
%A M. V. Persson
%A N. M. Murillo
%A R. Visser
%J -
%D 2020
%R 10.1051/0004-6361/201935994
%X <i>Context.<i/> Water is a key volatile that provides insight into the initial stages of planet formation. The low water abundances inferred from water observations toward low-mass protostellar objects may point to a rapid locking of water as ice by large dust grains during star and planet formation. However, little is known about the water vapor abundance in newly formed planet-forming disks.<i>Aims.<i/> We aim to determine the water abundance in embedded Keplerian disks through spatially-resolved observations of H O lines to understand the evolution of water during star and planet formation.<i>Methods.<i/> We present H O line observations with ALMA and NOEMA millimeter interferometers toward five young stellar objects. NOEMA observed the 3<sub>1,3<sub/><i>¨C<i/>2<sub>2,0<sub/> line (<i>E<i/><sub>up<sub/>¨M<i>k<i/><sub>B<sub/> = 203.7£¿K) while ALMA targeted the 4<sub>1,4<sub/><i>¨C<i/>3<sub>2,1<sub/> line (<i>E<i/><sub>up<sub/>¨M<i>k<i/><sub>B<sub/> = 322.0£¿K). Water column densities were derived considering optically thin and thermalized emission. Our observations were sensitive to the emission from the known Keplerian disks around three out of the five Class I objects in the sample.<i>Results.<i/> No H O emission is detected toward any of our five Class I disks. We report upper limits to the integrated line intensities. The inferred water column densities in Class I disks are cm<sup>£¿2<sup/> on 100 au scales, which include both the disk and envelope. The upper limits imply a disk-averaged water abundance of £¿10<sup>£¿6<sup/> with respect to H<sub>2<sub/> for Class I objects. After taking the physical structure of the disk into account, the upper limit to the water abundance averaged over the inner warm disk with <i>T<i/> > 100 K is between ~10<sup>£¿7<sup/> and 10<sup>£¿5<sup/>.<i>Conclusions.<i/> Water vapor is not abundant in warm protostellar envelopes around Class I protostars. Upper limits to the water vapor column densities in Class I disks are at least two orders of magnitude lower than values found in Class 0 disk-like structures
%U https://www.aanda.org/articles/aa/full_html/2020/04/aa35994-19/aa35994-19.html