Interaction of NGC 2276 with the NGC 2300 group: Fabry-Perot observations of the Hα velocity field

We report on kinematic observations of Hα emission from the spiral galaxy NGC 2276 obtained with the Maryland-Caltech Fabry-Perot Camera. The "bow shock" appearance and enhanced star formation in NGC 2276 have been attributed by Mulchaey et al. (1993) to a ram-pressure interaction with the dense IGM detected in ROSAT observations of the NGC 2300 group of galaxies. Along the "bow shock" limb of the galaxy we observe strong Hα emission and significant kinematic perturbations located immediately interior to an abrupt decrease in the scale length of the optical disk. Although ram-pressure forces may be important in the evolution of the outer gaseous disk, the peculiar kinematics and the truncation in the stellar disk are difficult to explain in a ram-pressure model; a more likely cause is tidal interaction, probably with the elliptical galaxy NGC 2300.