Comment on “Sensitive Test for Ion-Cyclotron Resonant Heating in the Solar Wind”

A Comment on the Letter by J. C. Kasper et al., Phys. Rev. Lett. 110, 091102 (2013).

Figure 1

Dispersion relation in Ref. 1 [light gray (green) line] and our Eq. (1) for $\delta v_{\alpha p}=0$ [medium gray (blue) line] and $\delta v_{\alpha p}=0.3$ [dark gray (red) line]. We also display the resonant condition for ${\mathrm{He}}^{+2}$ for $v_{\parallel \alpha }/C_A=0.168$ (black dashed line) and 0.3 (black dotted line).