how to add nine figures to a two column page?

Using the caption package one can declare a new format. Without the caption package you can simply put the caption into multicols.

\documentclass[twocolumn]{article}
\usepackage{graphicx}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{multicol}
\usepackage{blindtext}% MWE only

\DeclareCaptionFormat{twocolumn}{\begin{multicols}{2}#1#2#3\end{multicols}}

\begin{document}
\begin{figure*}
\centering
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}

\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}

\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}\hfil
\begin{subfigure}{0.3\textwidth}
\caption{}
\includegraphics[width=\textwidth]{example-image}
\end{subfigure}

\captionsetup{singlelinecheck=false,format=twocolumn}%
\caption[short caption]{\blindtext}
\end{figure*}
\end{document}

Using \documentclass{article}, it is simple to obtain the following:

\documentclass[12pt,twocolumn]{article}
\usepackage[a4paper]{geometry}
\usepackage[font=small, labelfont=bf]{caption}
\usepackage{subcaption}
\usepackage{graphicx}

\begin{document}
\begin{figure*}[htb]
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-a}% width
    \label{fig:myfig-a}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-b}% width
    \label{fig:myfig-b}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-c}% width
    \label{fig:myfig-c}
\end{subfigure}

\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-a}% width
    \label{fig:myfig-d}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-b}% width
    \label{fig:myfig-e}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-c}% width
    \label{fig:myfig-f}
\end{subfigure}

\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-a}% width
    \label{fig:myfig-g}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-b}% width
    \label{fig:myfig-h}
\end{subfigure}
\hfil
\begin{subfigure}{.3\textwidth}
  \caption{}
\includegraphics[width=\linewidth]{example-image-c}% width
    \label{fig:myfig-i}
\end{subfigure}

\caption{My figures}
    \end{figure*}
\end{document}

Unfortunately I haven't your document class and consequently if it have some issues with used packages.

Adapting my answer to Is it possible to have a two-column figure caption in revtex?

\documentclass{aastex}
%\usepackage{spr-astr-addons} % I haven't it

\usepackage{url}\urlstyle{rm}
\usepackage{graphicx}
\usepackage{color}
\usepackage[caption=false]{subfig}

\usepackage{lipsum}

\captionsetup[subfigure]{position=top}

\makeatletter
\newcommand{\twocolumncaption}{\@dblarg\@twocolumncaption}
\def\@twocolumncaption[#1]#2{%
  \renewcommand{\@makecaption}[2]{%
    \par\vskip\abovecaptionskip\begingroup\small\rmfamily
    \splittopskip=0pt
    \setbox\@tempboxa=\vbox{
      \@arrayparboxrestore \let \\\@normalcr
      \hsize=.5\hsize \advance\hsize-1em
      \let\\\heading@cr
      \noindent ##1\ ##2\par% this line for aastex
    }%
    \vbadness=10000
    \setbox\z@=\vsplit\@tempboxa to .55\ht\@tempboxa
    \setbox\z@=\vtop{\hrule height 0pt \unvbox\z@}
    \setbox\tw@=\vtop{\hrule height 0pt \unvbox\@tempboxa}
    \noindent\box\z@\hfill\box\tw@\par
    \endgroup\vskip \belowcaptionskip
  }%
  \setlength{\abovecaptionskip}{4ex}%
  \caption[#1]{#2}%
}
\makeatother



\begin{document}

\title{Title}
\author{A. Uthor}
\affil{Somewhere}

\begin{abstract}

\lipsum[2]

\begin{description}

\item[PACS numbers] 04.50.Kd, 04.20.-q, 04.25.Nx
\end{description}

\end{abstract}


\keywords{Keywords}

\maketitle

\section{Intro}

\lipsum[1-3]

\begin{figure*}
\centering

\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}\ 
\subfloat[]{\includegraphics[width=0.25\textwidth]{example-image}}

\twocolumncaption{%
Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut,
placerat ac, adipiscing vitae, felis. Curabitur dictum gravida mauris. Nam arcu libero, 
nonummy eget, consectetuer id, vulputate  a, magna. Donec vehicula augue eu neque. 
Pellentesque habitant morbi  tristique senectus et netus et malesuada fames ac turpis 
egestas. Mauris  ut leo. Cras viverra metus rhoncus sem. Nulla et lectus vestibulum 
urna  fringilla.}

\end{figure*}

\lipsum

\section{Conclusion}

\lipsum

\end{document}

If the Springer style already makes the two column caption, remove the code from \makeatletter to \makeatother (included) and just use \caption.