2009ApJ...699..469C

We report observations of the H166α (ν = 1424.734 MHz) radio recombination line (RRL) emission from the Galactic plane in the longitude range l = 267°-302° and latitude range b = -3°.0 to +1°.5. The line emission observed describes the Carina arm in the Galactic azimuth range from θ = 260° to 190°. The structure is located at negative latitudes with respect to the formal Galactic plane. The observations are combined with RRL data from the first Galactic quadrant. Both quadrants show the signature of the warp for the ionized gas, but an asymmetry of the distribution is noted. In the fourth quadrant, the gas is located between Galactic radii R ~ 7 and 10 kpc, and the amplitude of the warp is seen from the midplane to z ~ -150 pc. In the first quadrant, the gas is found between R ~ 8 and 13-16 kpc, and flares to z ~ +350 pc. We confirm the warp of the ionized gas near the solar circle. The distribution of the ionized gas is compared with the maximum intensity H I emission (0.30 < n_ H I_ < 0.45/cm3) at intervals of the Galactic ring. The ionized material is correlated with the H I maximum intensity in both quadrants, and both components show the same tilted behavior with respect to the mid-Galactic plane.