\begin{table}%t1 \par \caption{\label{tab:data_obs}Parameters of the observed solar twins.} %\centerline {\begin{tabular}{cccccccl} \hline\hline Name & $T_{\rm eff}$ & $(L/L_{\odot})$ & [Fe/H] & $\log N$(Li) & Age & Mass & Source$^a$ \\ & (K) & & & & (Gyr) & (\msun) & \\ \hline HIP~55~459 & $5812 \pm 50$ & $1.081 \pm 0.069$ & 0.066 & $1.58 \pm 0.07$ & $3.80^{+2.51}_{-2.10}$ & $1.03^{+0.05}_{-0.04}$ & (i)* \\ (HD 98~618) & $5837 \pm 36$ & $1.13 \pm 0.11$ & 0.030 & $1.55 \pm 0.08$ & $4.7 \pm 1.0$ & $1.03 \pm 0.03$ & (g)* \\ %%%%%%%%%% & $5812 \pm 44$ & (...) & $0.03 \pm 0.03$ & (...) & $4.9 \pm 2.9$ & $1.040 \pm 0.150$ & (c) \\ & $5843 \pm 30$ & (...) & $0.05 \pm 0.03$ & $1.57 \pm 0.09$ & $4.3 \pm 0.9$ & $1.02 \pm 0.03$ & (e) \\ HIP~79~672 & $5762 \pm 50$ & $1.043 \pm 0.027$ & 0.039 & $1.63 \pm 0.07$ & $4.57^{+0.33}_{-2.87}$ & $1.02^{+0.03}_{-0.02}$ & (i)* \\ (18 Sco) & $5853 \pm 36$ & $1.06 \pm 0.09$ & 0.040 & $1.63 \pm 0.08$ & $3.4 \pm 1.0$ & $1.04 \pm 0.03$ & (g)* \\ & $5789 \pm 30$ & (...) & $0.05 \pm 0.06$ & (...) & (...) & (...) & (a) \\ & 5823 & (...) & 0.03 & (...) & (...) & (...) & (b) \\ & $5791 \pm 44$ & (...) & $0.03 \pm 0.03$ & (...) & $4.7 \pm 2.7$ & $0.980 \pm 0.130$ & (c) \\ & $5817 \pm 30$ & (...) & $0.02 \pm 0.03$ & $1.63 \pm 0.09$ & $4.0 \pm 0.4$ & $1.02 \pm 0.03$ & (e) \\ & 5815 & (...) & 0.047 & 1.60 & (...) & (...) & (j) \\ HIP 100~963 & $5779 \pm 50$ & $0.968 \pm 0.043$ & --0.002 & $1.72 \pm 0.07$ & $5.13^{+0.00}_{-2.99}$$^b$ & $1.00^{+0.03}_{-0.02}$ & (i)* \\ & 5794 & (...) & (...) & (...) & (...) & (...) & (d) \\ & 5803 & (...) & -0.004 & 1.68 & (...) & (...) & (j) \\ HIP 56~948 & $5785 \pm 36$ & $1.15 \pm 0.14$ & 0.020 & $1.08 \pm 0.13$ & $5.8 \pm 1.0$ & $1.00 \pm 0.03$ & (g)* \\ & 5785 & (...) & (...) & (...) & (...) & (...) & (d) \\ & 5701 & (...) & -0.15 & (...) & 9.6 & $0.98 \pm 0.05$ & (f) \\ & 5791 & (...) & 0.020 & 1.13 & (...) & (...) & (j) \\ HIP 73~815 & $5810 \pm 36$ & $1.21 \pm 0.14$ & 0.010 & $0.95 \pm 0.20$ & $6.3 \pm 1.0$ & $1.00 \pm 0.03$ & (g)* \\ & 5759 & (...) & --0.05 & (...) & (...) & (...) & (h) \\ \hline \end{tabular}} \par \smallskip $^a$ {The sources of the observations are: (a) Porto de Mello \& da Silva (\cite{PortodeMello97}), (b) Luck \& Heiter (\cite{Luck05}), (c) Valenti \& Fisher (\cite{Valenti05}), (d) Masana et~al. (\cite{Masana06}), (e) Mel\'endez et~al. (\cite{Melendez06}), (f) Holmberg et~al. (\cite{Holmberg07}), (g)* Mel\'endez \& Ram\'irez (\cite{Melendez07}), (h) Robinson et~al. (\cite{Robinson07}), (i)* Takeda et~al. (\cite{Takeda07}), (j) Takeda \& Tajitsu (\cite{Takeda09}). The observations used in this work are represented by *.} $^b$ {Takeda et~al. (\cite{Takeda07}) give no estimation for the upper error of the age of HIP 100~963.} \par \end{table}