The Ionization Structure of Sharpless 2-264: Multiwavelength
  Observations of the {\lambda} Ori H II Region
  We present velocity-resolved maps taken with the Wisconsin H-Alpha Mapper
(WHAM) in H{\alpha}, [S II] {\lambda}6716, and [N II] {\lambda}6583 around the
well-known O8 III star {\lambda} Ori A (HD 36861) (l = 185{\deg} to 205{\deg},
b = -24{\deg} to -1{\deg}). The integrated intensity (v(LSR) = -80 to +80
km/s), I(H{\alpha}), within WHAM's one-degree beams varies from ~ 190 R near
the center to ~ 10 R on the periphery of the nebula where it becomes comparable
to foreground and/or background emission in this complex region. Intensity
ratios for [N II]/H{\alpha} and [S II]/H{\alpha} average 0.28 and 0.35,
respectively. In both ratios, higher values are found preferentially at larger
radii from {\lambda} Ori, although the behavior of [N II]/H{\alpha} is
complicated near the edges of the nebula. The [S II]/[N II] intensity ratio
ranges from ~ 0.5 to ~ 1.0, with the value increasing toward larger radii (and
lower H{\alpha} intensities). Variations of [S II]/H{\alpha}, [N II]/H{\alpha},
and [S II]/[N II] line ratios in this diffuse region show some similar trends
to those seen in the warm ionized medium (WIM) but with generally lower
metal-line ratios. As with the WIM, the trends are driven by changes in the
underlying physical parameters, most notably the ionization states and gas
temperature. We use these extremely high signal-to-noise observations to
construct a map of temperature and non-thermal velocity throughout the nebula.
Using the line widths of H{\alpha} and [S II], we separate thermal and
non-thermal components and find spatial trends of these parameters within the
nebula.
