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تسجيل مستخدم جديدCALIFA Spectroscopy of the Interacting Galaxy NGC 5394 (Arp 84): Starbursts, Enhanced [NII]6584 and Signs of Outflows and Shocks
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We investigate the spiral galaxy NGC 5394, which is strongly interacting with the larger spiral NGC 5395 (the pair is Arp 84), using optical integral-field spectroscopy from the CALIFA survey. Spatially-resolved equivalent-widths, emission-line ratios and kinematics reveal many features related to the interaction, which has reshaped the galaxy. $rm Halpha$ maps (with other diagnostic emission lines) show a concentrated central ($r<1$ kpc) starburst and three less luminous star-forming regions (one knot far out in the northern arm), and we estimate the dust-corrected total star-formation rate as 3.39 $rm M_{odot}yr^{-1}$. However, much of the galaxy, especially the outer tidal arms, has a post-starburst spectrum, evidence of a more extensive episode of star-formation a few $times 10^8$ yr ago, triggered by the previous perigalacticon. The $rm [NII]6584/Halpha$ ratio is high in the nucleus, reaching 0.63 at the centre, which we interpret as related to high electron density ($n_esimeq 750$ $rm cm^{-3}$ from the $rm [SII]{6717over 6731}$ ratio). We find a central region of strong and blueshifted NaI(5890,5896) absorption, indicative of a starburst-driven outflow from the nucleus at an estimated velocity $sim 223$ km $rm s^{-1}$. The CALIFA data also show an annular region at radii 2.25--4 kpc from the nucleus, with elevated ratios of [NII], [OI]6300 etc. to the Balmer lines -- this is evidence of shock excitation, which might be the result of interaction-triggered gas inflow.
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