1.
已知圆\(O\):\(x^{2}+y^{2}=4\),点\(A(- \sqrt{3},0)\),\(B( \sqrt{3},0)\),以线段\(AP\)为直径的圆\(C_{1}\)内切于圆\(O.\)记点\(P\)的轨迹为\(C_{2}\).
\((1)\)证明:\(|AP|+|BP|\)为定值,并求\(C_{2}\)的方程;
\((2)\)过点\(O\)的一条直线交圆\(O\)于\(M\),\(N\)两点,点\(D(-2,0)\),直线\(DM\),\(DN\)与\(C_{2}\)的另一个交点分别为\(S\),\(T.\)记\(\triangle DMN\),\(\triangle DST\)的面积分别为\(S_{1}\),\(S_{2}\),求\( \dfrac{S_{1}}{S_{2}}\)的取值范围.