\begin{table}%t1
\caption{Observation of Milky Way and M~31 (re-scaled to 785~kpc).}
\par
%\centerline
 {\small \begin{tabular}{lllll}
\hline  \hline
Observable  & Milky Way & Reference  & M~31  & Reference \\
\hline  
\textbf{Global properties} \\
\hline
Type & SbcI-II      & 1   & SbI-II           & 1\\
$K$-band   & $M_K=-24.02$ & 2   & $M_K=-24.70$     & 3 \\
Total luminosity             &              &     &                  &   \\
\qquad $L_B$ ($10^{10}~L_{B\odot}$) &  1.8  & 4   & 3.3              & 5 \\
\qquad $L_V$ ($10^{10}~L_{V\odot}$) &  2.1  & 6   & $2.6 \sim 2.7$     & 1 \\
\qquad $L_K$ ($10^{10}~L_{K\odot}$) &  5.5  & 7   & $6 \sim 12^a$  & 8 \\
Total colour ($B-V$)  &  0.84 & 4   & 0.81             & 9\\
Mass                                &       &     &                  &  \\
\qquad Total ($10^{10}$\ms)        & 40--55 & 10, 11 & 107--140     & 12\\
\qquad Visible ($10^{10}$\ms)      & 5.0   & 3      & $5.9-8.7$     & 5\\
 Rotational curve (\kms)             &       &        &                &  \\
\qquad Flat velocity               & 220   & 1      & 226            & 13 \\
\hline \hline 
\textbf{Bulge}                      &       &        &                &   \\
\hline
\qquad Stellar mass ($10^{10}$\ms) & 1--2   & 14     & 3.2            & 15  \\
\qquad Effective radius (kpc)      & 2.5   & 1      & 2.6            & 1   \\
\hline \hline
\textbf{Disk}          &                    &        &                & \\
\hline
 Scalelength (kpc)       &                    &        &                &  \\
\qquad $U$              &                    &        &  7.7           & 9 \\
\qquad $B$              & $4.0\sim5.0$       & 7      &  6.6           & 9 \\
\qquad $V$              & $2.5\sim3.5$       & 6, 16  &  6.0           & 9 \\
 \qquad $R$              &  2.3               & 3      &  5.9           & 9 \\
\qquad $I$              &                    &        & 5.7            & 17 \\
\qquad $K$              & $2.3\sim2.8$       & 18     & 4.8           & 19 \\
\qquad $L$              &                    &        & 6.08          & 8 \\
Total SFR (\ms~yr$^{-1}$)  & $\sim$1--5        & 20,21   & 0.35--1.0  & 1, 8, 21, 22\\
Infall rate (\ms\ ${\rm yr}^{-1}$)& $0.5\sim5$     & 21, 23 &               & \\
 Total mass of          &                    &        &                  & \\
\qquad disk($10^{10}$\ms) & 3.5$^b$       & 24     & $\sim$7       & 15, 25, 26\\
\qquad star($10^{10}$\ms) & 3.0$^c$       & 16     & $\sim$6   & 5\\
\qquad gas($10^{10}$\ms)  & $\sim$0.7  & 27, 28 & $\sim$0.6             & 29\\
      \qquad HI($10^{10}$\ms)   & 0.4            & 1      & $\sim$0.5   & 1, 29, 30\\
      \qquad H$_2$($10^{10}$\ms)& 0.11           & 31     & $\sim$0.02-0.04 & 29, 30, 31\\
Gas fraction & $\sim$0.15--0.2 & 20, This paper & $\sim$ 0.09  & This paper \\
Abundance gradient         &                  &            &                    & \\
\qquad [O/H] ({dex~kpc$^{-1}$})  & $-0.04 \sim -0.07$ & 32, 33, 34 & $-0.018 \sim -0.027$ & 35, 36\\
Colour gradient                &                &            &                & \\
\qquad $B-V$ (mag~kpc$^{-1}$) &              &            & 0.016              & 9\\
    \hline
   \end{tabular}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\medskip
Note: $^a$: Assuming $M/L_K = 1.15$ ($M/L_K)_{\odot}$ and  M~31 mass is taken
to be $(7-14)\times 10^{10}~M_\odot$; $^b$: derived based on the disk scalelength $r_{\rm d} = 2.3$~kpc and total disk surface density at the solar neighborhood $\Sigma_{\rm tot} = 50$~\ms\ ${\rm pc}^{-2}$; $^c$: derived based on the stellar disk scalelength $r_{\rm d} = 2.3$~kpc and stellar surface density at the solar neighborhood $\Sigma_{*}$ = 37 \ms\ ${\rm pc}^{-2}$. \\
\noindent Reference: (1)~van~den~Bergh (\cite{vandenBergh99}); (2)~Drimmel \& Spergel (\cite{Drimmel01}); (3)~Hammer et~al. (\cite{Hammer07}); (4)~van~der~Kruit (\cite{vanderKruit86}); (5)~Tamm et~al. (\cite{Tamm07}); (6)~Sackett (\cite{Sackett97}); (7)~Kent et~al. (\cite{Kent91}); (8)~Barmby et~al. (\cite{Barmby06}); (9)~Walterbos \& Kennicutt (\cite{Walterbos88}); (10)~Xue et~al. (\cite{Xue08}); (11)~Sakamoto et~al. (\cite{Sakamoto03}); (12)~Tempel et~al. (\cite{Tempel07}); (13)~Carignan et~al.
(\cite{Carignan06}); (14)~Dehnen \& Binney (\cite{Dehnen98}); (15)~Geehan et~al. (\cite{Geehan06}); (16)~Zheng et~al. (\cite{Zheng01}); (17)~Worthey et~al. (\cite{Worthey05}); (18)~Freudenreich (\cite{Freudenreich98});
(19)~Hiromoto et~al. (\cite{Hiromoto83}); (20)~Boissier \& Prantzos (\cite{Boissier99}); (21)~Fraternali (2009); (22)~Williams (\cite{Williams03})a; (23)~Blitz et~al. (\cite{Blitz99}); (24)~Holmberg \& Flynn (\cite{Holmberg04}); (25) Klypin et~al. (\cite{Klypin02}); (26) Widrow et~al.
(\cite{Widrow03}); (27)~Dame (\cite{Dame93}); (28) Kulkarni \& Heiles (\cite{Kulkarni87}); (29)~Nieten et~al. (\cite{Nieten06}); (30)~Dame et~al. (\cite{Dame93}); (31) Koper et~al. (\cite{Koper91}); (32)~Deharveng et~al. (\cite{Deharveng00}); (33)~Daflon \& Cunha (\cite{Daflon04}); (34)~Rudolph et~al. (\cite{Rudolph06}); (35)~Smartt et~al. (\cite{Smartt01}); (36)~Trundle et~al. (\cite{Trundle02}).
\end{table}