\begin{table}%t4 \caption{\label{model}Model results, reduced $\chi^2$ ($\chi^2_{\rm red.}$) assuming a fixed outer radius ($R_{\rm OUT}$) of 150~AU and a maximum grain size ($a_{\rm max}$) of 3~mm.} \par %\centering \par \begin{tabular}{lllllll} \hline \hline \multicolumn{1}{l}{} & \multicolumn{1}{l}{HD~104860}& \multicolumn{1}{l}{HD~8907}& \multicolumn{1}{l}{HD~377}& \multicolumn{1}{l}{HD~107146}& \multicolumn{1}{l}{HD~61005 }& \multicolumn{1}{l}{HD~191089} \\ \hline $M_{\rm dust}/M_{\oplus}$&$0.082\pm0.007$& $0.040\pm0.005$ &$0.058\pm0.013$ &$0.110\pm0.008$&$0.261\pm0.023$ & $0.110\pm0.037$ \\ $R_{\rm in}$ [AU] &$21\pm5$&$27.8\pm13.9$ &$6.1\pm0.8$ &$10.2\pm0.8$ &$95.6\pm23$&$79\pm98$ \\ $a_{\rm min}$ [$\mu$m]&$8\pm2$&$6\pm2$&$14\pm5$&$8.6\pm1.2$&$0.4\pm0.3$ &$0.23\pm0.78$ \\ $\chi^2_{\rm red.}$ & 2.6&4.3 &5.0 &4.5&16.3 &8.7\\ \hline \end{tabular} \end{table}