  Assume that $\Delta$ is the open unit disk in the complex plane and
$\mathcal{A}$ is the class of normalized analytic functions in $\Delta$. In
this paper we introduce and study the class \begin{equation*}
  \mathcal{BS}(\alpha):=\left\{f\in \mathcal{A}:
\left(\frac{zf'(z)}{f(z)}-1\right)\prec \frac{z}{1-\alpha z^2}, \,
z\in\Delta\right\}, \end{equation*} where $0\leq\alpha\leq1$ and $\prec$ is the
subordination relation. Some properties of this class like differential
subordination, coefficients estimates and Fekete-Szeg\"{o} inequality
associated with the $k$-th root transform are considered.
