  Solar wind parameters play a dominant role in reconnection rate, which
controls the solar wind-magnetosphere coupling efficiency at Earth's
magnetopause. Besides, low-energy ions from the ionosphere, frequently detected
on the magnetospheric side of the magnetopause, also affect magnetic
reconnection. However, the specific role of low-energy ions in reconnection is
still an open question under active discussion. In the present work, we report
in situ observations of a multiscale, multi-type magnetopause reconnection in
the presence of low-energy ions using NASA's Magnetospheric Multiscale data on
11 September 2015. This study divides ions into cold and hot populations. The
observations can be interpreted as a secondary reconnection dominated by
electrons and cold ions located at the edge of an ion-scale reconnection. This
analysis demonstrates a dominant role of cold ions in the secondary
reconnection without hot ions' response. Cold ions and electrons are
accelerated and heated by the secondary process. The case study provides
observational evidence for the simultaneous operation of antiparallel and
component reconnection. Our results imply that the pre-accelerated and heated
cold ions and electrons in the secondary reconnection may participate in the
primary ion-scale reconnection affecting the solar wind-magnetopause coupling
and the complicated magnetic field topology affect the reconnection rate.
