Star formation efficiency in the central 1 kiloparsec region of early-typespiral galaxies

It has been reported recently that there are some early-type spiral (Sa-Sab ) galaxies with evident star-forming regions that concentrate in their own central 1 kpc. In such central region, is the mechanism of the star formati on distinct from that in disks of spiral galaxies? To discover this, we est imate the star formation efficiency (SFE) in this central 1 kpc star-formin g region of some early-type spiral galaxies, taking account of the conditio n required for this 1 kpc region to be self-gravitating. Using two indicato rs of the present star formation rate (H alpha and infrared luminosity), we estimate the SFE to a few percent. This is equivalent to the observational SFE in the disks of late-type spiral (Sb-) galaxies. This coincidence may support the universality of the mean SFE of spiral galaxies reported in the recent studies, that is, we find no evidence of a distinct mechanism of th e star formation in the central 1 kpc region of early-type galaxies. Also, we examine the structure of the central star-forming region and discuss a m ethod for estimating the mass of star-forming regions.