Linear stability of the elliptic relative equilibrium with $(1+n)$-gon central configurations in planar $n$-body problem

We study the linear stability of $(1+n)$-gon elliptic relative equilibrium (ERE for short), that is the Kepler homographic solution with the $(1+n)$-gon central configurations. We show that for $n\ge 8$ and any eccentricity $e\in [0,1)$, the $(1+n)$-gon ERE is stable when the central mass $m$ is large enough. Some linear instability results are given when $m$ is small.