The term "sun graph" has several differing definitions. ISGCI defines a (complete) 
-sun
graph as a graph on 
vertices (sometimes also
known as a trampoline graph; Brandstädt et al. 1999, p. 112) consisting
of a central complete graph 
with an outer ring of 
vertices, each of which is
joined to both endpoints of the closest outer edge
of the central core.
Wallis (2000), Anitha and Lekshmi (2008), and the American Institute of Mathematics use the term "
-sun"
graph to instead refer to the graph on 
vertices obtained by attaching
pendant edges
to a cycle graph 
. These graphs are referred to
as "sunlet graphs" by ISGCI. The 3-sunlet
graph 
is also known as the net graph.
The sun graphs are pancyclic and uniquely Hamiltonian.
