1995A&A...295..302B

High angular resolution CO(2-1) and (1-0) observations are reported from the central region of the Magellanic-type irregular galaxy NGC 4214. CO(2-1) spectra were obtained with a beam size of 13" (340pc at D=5.4Mpc) toward 20 positions. At eight positions, emission was detected from a molecular cloud complex with a size of 1000pcx700pc (at the 0.7K.km/s contour) and a mass of a few ∼10⁷M_☉. The I_CO(2–1)/I_CO(1–0) line intensity ratio is 0.4, indicating emission from optically thick subthermally excited lines. Comparing virial masses with masses deduced from the integrated CO intensities yields an N_H2/I_CO conversion factor, which is a few times the standard Galactic value of 2.3x10²⁰(cm²K.km/s). On the basis of radial velocity, the huge CO complex is resolved into a western, a central, and an eastern component. The radial velocities, 298, 308, and 305km/s, demonstrate that the E-W velocity change across the central bar is not smooth on linear scales <1kpc. A prominent loop of Hα emission (diameter: ∼250pc) is found at the interface between the western and eastern complex. A narrow linewidth and a lack of associated Hα emission indicates that the western CO complex is in a quiescent state. The eastern region, being located close to the starburst knot at the optical center of the galaxy, exhibits broader CO lines and intense Hα emission and must form massive stars.