2015MNRAS.450..998S

We present a photometric and spectroscopic study of the polar ring galaxy A0136-0801 in order to constrain its formation history. Near-infrared and optical imaging data are used to extract surface brightness and colour profiles of the host galaxy and the wide polar structure in A0136-0801. The host galaxy dominates the light emission in all bands; the polar structure is more luminous in the optical bands and is three times more extended than the main spheroid. The average stellar population in the spheroid is redder than in the polar structure and we use their (B - K) versus (J - K) colours to constraint the ages of these populations using stellar population synthesis models. The inferred ages are 3-5 Gyr for the spheroid and 1-3 Gyr for the polar structure. We then use long slit spectra along the major axis of the polar structure to derive the emission line ratios and constrain the oxygen abundance, metallicity and star formation rate in this component. We find 12 + log(O/H) = 8.33±0.43 and Z ≃ 0.32Z_☉, using emission line ratios. These values are used, together with the ratio of the baryonic masses of the host galaxy and polar structure, to constrain the possible models for the formation scenario. We conclude that the tidal accretion of gas from a gas-rich donor or the disruption of a gas-rich satellite are formation mechanisms that may lead to systems with physical parameters in agreement with those measured for A0136-0801.