Double Bars, Inner Disks, and Nuclear Rings in Early-Type Disk Galaxies

摘要: We present results from a survey of an unbiased sample 38 early-type (S0–Sa), low-inclination, optically barred galaxies in the field, using images both ground and space. Our goal was to find characterize central stellar gaseous structures: secondary bars, inner disks, nuclear rings. that bars inside are surprisingly common: at least one-quarter (possibly as many 40%) double barred, with no preference for Hubble type or strength primary bar. A typical bar is ~12% size its extends 240–750 pc radius. Secondary not systematically either parallel perpendicular primary; we see cases where they lead rotation others trail, which supports hypothesis two double-bar system rotate independently. significant effect on activity: our double-barred more likely harbor Seyfert LINER nucleus than single-barred galaxies. kiloparsec-scale disks 20% sample; occur almost exclusively S0 These average their host show wider range relative sizes do bars. Nuclear rings about third sample. Most these dusty, sites current recent star formation, both; such preferentially found Sa Three (8% sample, but 15% S0's) appear have purely rings, evidence dust formation. The fact structures so common indicates regions typically contain dynamically cool disklike structures. This especially true galaxies, and/or two-thirds time. If interpret (possibly) spirals signs Lindblad resonances (ILRs), then between one S0–Sa ILRs.