= Field-independent stationary threshold in oblique magnetoconvection
{title2=$\alpha=\arctan\sqrt2,\quad k_c=-1/\sqrt2,\quad R_c=27/4$}
At inclination $\alpha=\arctan\sqrt2$ and vertical wavenumber one, the nonmagnetic minimizing wavenumber $k=-1/\sqrt2$ also satisfies $\mathbf c\cdot\mathbf k=0$. The stationary threshold is the sum of $F(k)\geq27/4$ and a nonnegative magnetic penalty that vanishes there. Therefore $k_c=-1/\sqrt2$ and $R_c=27/4$ for every $Q\geq0$. The selected disturbance is constant along the imposed field, so the linear <resistive induction equation> produces no magnetic perturbation and there is no field-line tension penalty.
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