\begin{table}%t3 \caption{\label{sam}Ultracool M dwarfs with detected quasi-quiescent X-ray emission.} \small%\centerline { \begin{tabular}{llrrrrrl} \hline\hline Star & Sp. type &$V \sin~i$ & Bf& log $L_{\rm H\alpha}$/$L_{\rm bol}$& log $L_{\rm X}$ & log $L_{\rm X}/L_{\rm bol}$& Ref.(X-ray) \\ \hline &&&&&&& \\[-8pt] VB 10~$^{a}$ & M8 &6& 1.3& $-$4.4/$-$5.0 &25.4 & $-$4.9 & \cite{fle03}~$^{\rm{1}}$\\ LP~412-31~$^{a}$& M8 &9& $>$3.9&$-$3.9/$-$4.4& 27.2 & $-$3.1 & \cite{ste06}\\ TVLM 513-46546~$^{b}$ & M8.5 &60 &$-$& $-$4.8/$-$5.0& 24.9 & $-$5.1 & \cite{ber08a}\\ LHS~2065~$^{a}$ & M9 &12& $>$3.9&$-$4.0/$-$4.3&26.3 & $-$3.7 & \cite{rob08a}~$^{\rm{2}}$\\ 1RXS~J115928.5-524717~$^{c}$ & M9 & 25 &$-$&$-$&26.0 & $-$4.1 & this work\\ \hline \end{tabular}} \medskip $^{a}$ Additional values from \cite{rei07}; $^{b}$ from \cite{moh03}; $^{c}$ from \cite{ham05}. \\ $^{\rm{1}}$ Re-observed by \cite{ber08b}; $^{\rm{2}}$ detected at specific times also by \cite{schmitt02}. \end{table}