The interaction between the interstellar medium and star formation in the dwarf starburst galaxy NGC 4214

We present the first interferometric study of the molecular gas in the meta l-poor dwarf starburst galaxy NGC 4214. Our map of the (CO)-C-12 (1-0) emis sion, obtained at the Owens Valley Radio Observatory's millimeter array, re veals an unexpected structural wealth. We detected three regions of molecul ar emission in the northwest, southeast, and center of NGC 4214 that are in very different and distinct evolutionary stages (total molecular mass: sim ilar to5.1 x 10(6) M.). These differences are apparent most dram matically when the CO morphologies are compared with optical ground-based and Hubble Space Telescope imaging: massive star formation has not started yet in the northwestern region; the well-known starburst in the center is the most evo lved, while star formation in the southeastern complex has begun more recen tly. We derive a star formation efficiency of similar to8% for the southeas tern complex. Using high-resolution VLA observations of neutral hydrogen (H I) and our CO data, we generated a total gas column density map for NGC 42 14 (H I +H-2). No clear correlation is seen between the peaks of H I, CO, a nd the sites of ongoing star formation. This emphasizes the irregular natur e of dwarf galaxies. The H I and CO velocities agree well, as do the H alph a velocities. In total, we cataloged 14 molecular clumps in NGC 4214. Our r esults from a virial mass analysis are compatible with a Galactic conversio n CO-to-H-2 factor for NGC 4214 (lower than what is usually found in metal- poor dwarf galaxies).