tokens: because the gas is ionized. We searched for a warm ionized gas associated with GS040 using the Wisconsin H α Mapper Northern Sky Survey (WHAM-NSS) data (Haffner et al. 2003 ). The survey has an angular resolution of 1°, and, around the GS040 area, it provides H α spectra covering from −85 to +100 km s −1 at spectral resolutions of 12 km s −1 . We have examined the H α intensity map integrated over the velocity range of GS040 (−85 to −66 km s −1 ), but could not detect an associated emission ( 0.05 R where ). Note that this area is bright in the total H α intensity map with a mean intensity of about 3 R , so that we do not expect to see the faint emission associated with either GS040 or CHVC040 in the all-sky H α maps (Dennison et al. 1998 ; Finkbeiner 2003 ). We also searched for an associated hot ionized gas using the 0.1–2.4 keV image of the ROSAT All-Sky X-ray Survey (1 pixel scale = 44′′; Voges et al. 1999 ) but could not detect any emission. CHVC040 belongs to the “Galactic Center Negative” (GCN) HVC complex, which is a collection of small discrete HVCs sparsely distributed over a area within and to 10° (Wakker van Woerden 1991 ; Winkel et al. 2011 ). A kinematic model has been proposed where GCN is a smooth gas flow starting at at a heliocentric distance of 35 kpc and crossing the Galactic plane obliquely at 15 kpc (Jin 2010 ). For comparison, GS040 is probably located near the Scutum-Centaurus (Sct-Cen) arm at a distance of ∼20 kpc (Dame Thaddeus 2011 ) because the disrupted interstellar medium (ISM) is seen only at velocities below that of the Sct-Cen arm ( km s −1 ), not at higher velocities (see Figures 2 and 3 ). We examined lists of known stellar objects, H ii regions, OB stars, and SN remnants, but no known sources are likely to be associated with GS040. There is one H ii region (G039.864+00.645) in the WISE catalog of Galactic H ii regions (Anderson et al. 2014 ) that is located at west of the hub. But this H ii region has a systematic velocity of −40.9 km s −1 (Anderson et al. 2011 ) and is enclosed by a small (68′′) dust shell, so it cannot be responsible for the H i shell. Instead, the distance of ∼20 kpc is not unreasonable for CHVC040, because GCN does not have a smooth extended envelope like other HVC complexes, and it appears to be composed of several subpopulations that do not share a common origin (Winkel et al. 2011 ). Note that the geometrical center of GS040 is well below the Galactic plane ( pc where ), i.e., at while the midplane there is at because the Galactic plane is warped in the outer Galaxy (Levine et al. 2006 ). It is difficult to imagine the SN origin for a supershell at such height, and CHVC040 is most likely the energy/momentum source for GS040. The total energy deposited ( E E ) in the Galactic disk by CHVC040 can be inferred from the parameters of the GS040 supershell. The radius of GS040 is pc, while its mass at km s −1 is including the cosmic abundance of helium. If we account for the mass
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