Large-scale nested stellar discs in NGC 7217статья
Статья опубликована в высокорейтинговом журнале
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:NGC 7217 is an unbarred early-type spiral galaxy having multi-segment
exponential brightness profile and a system of starforming rings of unknown
origin. We analysed new long slit spectroscopic data for NGC 7217 and derived
the radial distributions of its stellar population parameters and stellar and gaseous
kinematics up to the radius of r~100" (8 kpc). We
performed the dynamical analysis of the galaxy by recovering its velocity
ellipsoid at different radii, and estimated the scaleheights of its two
exponential discs. The inner exponential stellar disc of NGC 7217
appears to be thin and harbours intermediate age stars
(5 Gyr). The outer stellar disc seen between the radii
of 4 and 7 kpc is very thick (1-3 kpc), metal-poor,
[Fe/H]<-0.4 dex, and has predominantly young stars, t_{SSP}=2 Gyr. The
remnants of minor mergers of gas-rich satellites with an early-type giant
disc galaxy available in the GalMer database well resemble different
structural components of NGC 7217, suggesting two minor merger events in the
past responsible for the formation of the inner polar gaseous disc and large
outer starforming ring. Another possibility to form the outer ring is the re-accretion
of the tidal streams created by the first minor merger.