Dating the formation of the counter‐rotating stellar disc in the spiral galaxy NGC 5719 by disentangling its stellar populations★

摘要: We present the results of VLT/VIMOS integral-field spectroscopic observations inner 28 × arcsec 2 (3.1 3.1 kpc ) interacting spiral NGC 5719, which is known to host two cospatial counter-rotating stellar discs. At each position in field view, observed galaxy spectrum decomposed into contributions spectra and one ionized-gas components. measure kinematics line strengths Lick indices model data component with single population models that account for α/Fe overabundance. also derive distribution disc, associated younger, less rich metals, more α-enhanced, luminous component. They are both counter rotating respect main body galaxy. These findings prove scenario where gas was accreted first by 5719 on a retrograde orbit from large reservoir available its neighbourhoods as result interaction companion 5713, subsequently fuelled situ formation disc.