\begin{table}%tb.1 %\centering \par \caption{\label{Table:1}(Circum)stellar parameters for IK~Tau \citep{Decin2010}.} \begin{tabular}{lc|lc} \hline \hline%\noalign{\smallskip} {\Teff} [K] & 2200 & $[$CO/H$_{\rm{tot}}]$ & $1 \times 10^{-4}$ \\ $R_{\star}$ [$10^{13}$~cm] & 1.5 & $^{12}$CO/$^{13}$CO & 14 (7) \\ {\Mdot} [{\Msun}/yr] & $8 \times 10^{-6}$ & $[^{28}$SiO/H$_{\rm{tot}}]$ & $8 \times 10^{-6}$ ($4 \times 10^{-6}$) \\ distance [pc] & 265 & $[^{29}$SiO/H$_{\rm{tot}}]$ & $3 \times 10^{-7}$ \\ $R_{\rm{inner}}$ [\Rstar] & 8.7& $[^{30}$SiO/H$_{\rm{tot}}]$ & $1 \times 10^{-7}$ \\ $\varv_{\infty}$ [km~s$^{-1}$] & 17.7 & $[$HCN/H$_{\rm{tot}}]$ & $2.2 \times 10^{-7}$\\ $\varv_{\rm{turb}}$ [km~s$^{-1}$] & 1.5 & [SO/H$_{\rm{tot}}]$ & $1 \times 10^{-6}$ ($1 \times 10^{-5}$)\\ \hline \rule[0mm]{0mm}{5mm}$[$ortho-H$_2^{16}$O/H$_{\rm{tot}}]$ & $2.5 \times 10^{-5}$ & OPR & 3:1\\ H$_2^{16}$O/H$_2^{17}$O & 600 & H$_2^{16}$O/H$_2^{18}$O & 200 \\ \hline \end{tabular} \tablefoot{\Teff\ is the effective stellar temperature, \Rstar\ denotes the stellar radius, \Mdot\ the gas mass-loss rate, $R_{\rm{inner}}$ the dust condensation radius, $\varv_{\infty}$ the terminal velocity of the wind, and $\varv_{\rm{turb}}$ the turbulent velocity in the wind. The molecular fractional abundances are given relative to H$_{\rm{tot}}$=n(H)+2n(H$_2$), and denote the abundance at the dust condensation radius (see Fig.~\ref{fig:abundances}). Values between parentheses denote refined inner wind abundance values obtained from the new HIFI observations.The fractional abundances for all water isotopologs and isomers are based on the HIFI data presented in this Letter.} \end{table}