Star-forming Rings in Lenticular Galaxies: Origin of the Gasстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 10 октября 2019 г.
Аннотация:Rings in S0s are enigmatic features that can, however, betray the evolutionary paths of particular galaxies. We have undertaken long-slit spectroscopy of five lenticular galaxies with UV-bright outer rings. The observations have been made with the Southern African Large Telescope to reveal the kinematics, chemistry, and ages of the stellar populations and the gas characteristics in the rings and surrounding disks. Four of the five rings are also bright in the H-alpha emission line, and the spectra of the gaseous rings extracted around the maxima of the Halpha equivalent width reveal excitation by young stars revealing current star formation in the rings. The integrated level of this star formation is 0.1-0.2 solar mass per year, with the outstanding value of 1 solar mass per year in NGC 7808. The difference of chemical composition between the ionized gas of the rings, which demonstrate nearly solar metallicity, and the underlying stellar disks, which are metal-poor, implies recent accretion of the gas and star formation ignition; the star formation history estimated by using different star formation indicators implies that the star formation rate decreases with an e-folding time of less than 1 Gyr. In NGC 809, where the UV ring is well visible but the H-alpha emission line excited by massive stars is absent, the star formation has already ceased.