在两个表格中对齐

Question

什么提供了这一点，\pm在本代码中是一致的（来源)？

\documentclass{article}
\usepackage{siunitx}

\begin{document}
    \begin{table}
\renewcommand{\arraystretch}{1.3}
\sisetup{separate-uncertainty,
         table-column-width=6em}
\begin{tabular}{S[table-format = 3.2(3)]
                S[table-format = 4.2(4)]}
    \hline\hline
\hphantom{XX}F
            & \hphantom{XXx}R        \\
\hline
 42.34(16)  &   42.34(16)           \\
424.34(16)  & 5542.34(5016)         \\
    \hline
\end{tabular}\\
\begin{tabular}{S[table-format = 4.2]
                S[table-format = 5.2]}
21.9        &   20.8                \\
 9.1        &    8.7                \\
    \hline
\end{tabular}
    \end{table}
\end{document}

我尝试了一下，结果是错误的。

编辑

有错误的代码

\documentclass{article}
\usepackage{siunitx}

\newcommand{\Rnom}{\hbox{$\mathcal{R}^{\rm N}_\odot$}}
\newcommand{\Mnom}{\hbox{$\mathcal{M}^{\rm N}_\odot$}}
\newcommand{\st}{$^\circ$}

\begin{document}
    \begin{table}
\renewcommand{\arraystretch}{1.3} 
\sisetup{separate-uncertainty,
         table-column-width=10em}
\begin{tabular}{lS[table-format = 3.2(3)]
                S[table-format = 1.2(3)]}
    \hline\hline
ADFJHFK   &AGHDFG & FDJDFH     \\
\hline
$a$ (\Rnom)                   &  41.91(18)  &   40.71(21)        \\
$\omega$ (\st)                & 148.73(149) &       158.37(71)        \\
\end{tabular}\\
\begin{tabular}{lS[table-format = 2.3]
                S[table-format = 2.3]}
$M_1$ (\Mnom)  &    21.1    &   19.4  \\
$M_2$ (\Mnom)  &    8.8     &   8.1   \\
    \hline
\end{tabular}
    \end{table}

    \end{document}