Extended Data Fig. 4: Integrated spectra of V883 Ori centered on the HDO 225 GHz, HDO 241 GHz, and \({{{\bf{H}}}_{{\bf{2}}}}^{{\bf{18}}}{\bf{O}}\) 203 GHz lines.

Panels a, c, e show the spectra as observed (disk rotation causes all spectral lines to have a double-peaked line profile), while panels b, d, f show the stacked spectra^40,41 with the Keplerian rotation profile removed. The root mean squared (RMS) noise of the HDO 225 GHz, HDO 241 GHz, and \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\) are 0.016, 0.017, and 0.011 Jy, respectively. The HDO lines are the brightest features around their centre frequencies, but both have contaminating emission from COM species nearby. The \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\) line is faint relative to its surrounding features but is still clearly detected. We are able to model the spectral profiles for HDO, \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\), and the contaminating lines to measure their line fluxes using an optically-thin synthetic spectral model for a disk (Extended Data Fig. 5). In a, c, e, the observed spectrum is drawn as the black line, the model of the contaminating lines is drawn as an orange line, the model HDO and \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\) lines are drawn as blue lines, and the total model of contaminating lines with HDO and \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\) is drawn as a green line. The rise seen toward higher frequencies on the \({{{\rm{H}}}_{2}}^{18}{\rm{O}}\) spectrum (e) is another CH₃OCH₃ line that peaks outside the shown region. The spectra are plotted at their observed frequencies and are not corrected for the system local standard of rest (LSR) velocity of ~ 4.25 km s⁻¹.