\begin{table}%t1
\caption{\xmm\ observations used in this work.}\label{tab:obs_table}
\small%\centerline
 {
\begin{tabular}{c c c c c c c}
\hline \hline
&&&&&& \\[-8pt]
Obs. ID &  HD & Other name & Exposure (ks) &Start time & Type & Distance (pc)$^{H}$  \\
\hline
148790101 & 16157   & CC Eri  & 22.36 & 2003-08-08 09:21:36 & K7Ve/M4$^{S}$  & 11.51 \\
111520101 & 12230   & 47 Cas & 50.9  & 2001-09-11 02:21:19 & F0V+G$^{\natural}$ & 33.56 \\
112880701 & 19356   & Algol    & 45     & 2002-02-12 04:42:18 & B8V+G8III$^{B}$ & 28.46 \\
111530101 & 129333 & EK Dra & 54.9  & 2000-12-30 14:45:20 & G0V$^{H}$ & 33.94 \\
134540401 & 22468 & HR1099 & 26.42& 2001-08-18 03:47:57 & G5IV+K1IV$^{S}$ & 28.97 \\
49350101   & -- & Proxima Cen & 67.41 & 2001-08-12 04:16:02 & M5.5V$^{H}$ & 1.295 \\
56030101   & 131156 & $\xi$~Boo & 59 & 2001-01-19 11:14:41 & G8V$^{H}$ & 6.7 \\
111480101 & 62044 & $\sigma$~Gem & 55.8 & 2001-04-06 16:46:36 & K1III$^{H}$ & 37.48 \\
\hline
\end{tabular}}
\medskip
$ ^H$ -- HIPPARCOS catalog \citep{Hipparcos}.  
$ ^S$ -- \citet{Strassmeier1993}.  
$ ^B$ -- \citet{Budding2004}.  
$^\natural$ -- X-ray active component is not detected directly in the optical. 
It is assumed to be a fast rotating solar analog \citep{Guedel1998, Telleschi2005}.
\end{table}