HST observations of nuclear stellar disks

摘要: We present observations of four nearby early-type galaxies with previously known nuclear stellar disks using two instruments on-board the Hubble Space Telescope. observed NGC 4128, NGC 4612, and NGC 5308 Wide Field Planetary Camera 2, same three galaxies, plus NGC 4570, Telescope Imaging Spectrograph. have detected a red nucleus in blue NGC 4621, disk NGC 5308. Additionally, we discovered disk-like feature position angle ~$15\degr$ from major axis NGC 4621. In there is evidence for region along minor axis. transient on images NGC 4128 at position $0\farcs14$ west and $0\farcs32$ north nucleus. The extracted kinematic profiles belong to groups: fast (NGC 4570 NGC 5308) kinematically disturbed rotators (NGC 4128 NGC 4621). report discovery decoupled core NGC 4128. Galaxies mostly old (10-14 Gyr) populations large spread metallicities (sub- super-solar). discuss possible formation scenarios, including bar-driven secular evolution influence mergers, which can explain color features.