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We investigate the spiral galaxy NGC 5394, which is strongly interacting withthe larger spiral NGC 5395 (the pair is Arp 84), using optical integral-fieldspectroscopy from the CALIFA survey. Spatially-resolved equivalent-widths,emission-line ratios and kinematics reveal many features related to theinteraction, which has reshaped the galaxy. $\rm H\alpha$ maps (with otherdiagnostic emission lines) show a concentrated central ($r<1$ kpc) starburstand three less luminous star-forming regions (one knot far out in the northernarm), and we estimate the dust-corrected total star-formation rate as 3.39 $\rmM_{\odot}yr^{-1}$.  However, much of the galaxy, especially the outer tidal arms, has apost-starburst spectrum, evidence of a more extensive episode of star-formationa few $\times 10^8$ yr ago, triggered by the previous perigalacticon. The $\rm[NII]6584/H\alpha$ ratio is high in the nucleus, reaching 0.63 at the centre,which we interpret as related to high electron density ($n_e\simeq 750$ $\rmcm^{-3}$ from the $\rm [SII]{6717\over 6731}$ ratio). We find a central regionof strong and blueshifted NaI(5890,5896) absorption, indicative of astarburst-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--4kpc from the nucleus, with elevated ratios of [NII], [OI]6300 etc. to theBalmer lines -- this is evidence of shock excitation, which might be the resultof interaction-triggered gas inflow.

CALIFA Spectroscopy of the Interacting Galaxy NGC 5394 (Arp 84): Starbursts, Enhanced [NII]6584 and Signs of Outflows and Shocks