H&K feature with both a single Gaussian and a double Gaussian. We show the measured velocity in Figure \[f:spar\].

![*Top Panel:* Measured velocity as a function of excitation temperature for [SYNOW]{} model spectra. The red dotted lines represent the velocities measured with a single Gaussian for the [Si$\,$]{} $\lambda 4130$ and $\lambda 6355$ lines. The black crosses represent velocities measured with a single-Gaussian fit to the Ca H&K feature. The blue X’s represent velocities measured with a double-Gaussian fit to the Ca H&K feature, where the [Si$\,$]{} $\lambda 3858$ velocity is measured assuming its rest wavelength is 3945 Å. *Bottom Panel:* The $\mathcal{R}$(Si) (red dotted line) and Si/Ca (blue X’s) line ratios as a function of excitation temperature for the [SYNOW]{} model spectra.[]{data-label="f:spar"}](synow_par){width="3.2in"}

The measured [Si$\,$]{} $\lambda 4130$, and $\lambda 6355$ velocities differ by at most 530 and 220 [kms$^{-1}$]{} over the entire temperature range, respectively. At the lowest $T_{\rm exc}$, the [Si$\,$]{} $\lambda 5972$ feature is not strong enough to measure a reliable velocity, but for the other temperatures, it differs by at most 440 [kms$^{-1}$]{}. These differences are encouraging since the photospheric velocities did not change.

Fitting two Gaussians to the Ca H&K feature, which should be better 