THE AQUILA SUPERSHELL - A REMNANT OF MULTIPLE SUPERNOVAE

A large area surrounding the Aquila Supershell (GS 034-06 + 65) was ma pped in the H I 21 cm emission line. The new data show that the struct ure consists of an irregular spherical shell about 5.degrees 6 in diam eter, which extends 9.degrees 5 below the Galactic plane, and of a wel l-defined, massive cone at low latitudes, which connects to a molecula r cloud in the Galactic plane through a narrow (20 pc wide) channel of reduced H I emission. The system probably lies at a distance of simil ar to 3.3 kpc, which implies that the shell has a diameter of similar to 320 pc and extends at, least 550 pc into the Galactic halo. We esti mate that the swept-up mass in the shell is 6.0 x 10(4) M(.) and the m ass in the cone is 1.8 x 10(5) M(.). The concentration of supernova re mnants, star-forming regions, and H II regions in this direction impli es that the Aquila Supershell is a remnant of multiple supernovae and that star formation activity persists in this region of the Galaxy. We estimate that the total energy of the events creating the remnant is (1-5) x 10(52) ergs, which corresponds to 10-100 supernova explosions powering the system in 10(7) yr. It is possible that the W48 complex o f H II regions has resulted from star formation induced by a shock wav e related to the cone.