\documentstyle{article}

\title{The influence of Mass-loss on the orbit of comet SL9}
\author{Zheng Xuetang and Yu Lizhong\\
Dept. of Applied  Physics, Nanjing University of Science and Technology\\
Namjing, China}
\date{}

\begin{document}
\maketitle

Using the Jeans problem and the Fermi problem of two bodies with variable masses,
the influence of solar and cometary mass-loss on the orbit of comet SL9 is
dicussed in this paper. It is shown that solar and cometary mass-loss both will
cause the secular and periodic terms in the semimajor axis aof comet SL9. The
influence of solar mass-loss on the orbit of comet SL9 is very small and it may
be omitted. But the influence of mass-loss of comet SL9 itself on its orbit is
large and it may cause the secular variation in a to be about 1000km every year.
The cometary  mass-loss will influence the time and place of the collision of the
comet SL9 with Jupiter. Therefore it should be considered in the orbit
calculation and prediction of comet SL9

\end{document}
