6.
已知定圆\(M:{{(x+\sqrt{3})}^{2}}+{{y}^{2}}=16\),动圆\(N\)过点\(F(\sqrt{3},0)\)且与圆\(M\)相切,记动圆的圆心\(N\)的轨迹为\(\Gamma \).
\((1)\)求轨迹\(\Gamma \)的方程;
\((2)\)已知两定点\(A(-2,0)\)和\(B(1,0)\),过\(B\)的动直线\(l\)交轨迹\(\Gamma \)于\(P\),\(Q\)两点\(.\)若直线\(AP\)的斜率为\(k_{1}\),直线\(AQ\)的斜率为\(k_{2}\),求证\(k_{1}·k_{2}\)为定值.