The Merging System Am 2049-691

Abstract

Spectroscopic and photometric observations of the peculiar object AM 2049-691 are presented here. Its systemic velocity is V(GSR) = (10956 +-30) km/s, and the derived distance (H(0) = 75 km/s/Mpc) results 146 Mpc. A bridge is observed between two very distinct nuclei whose separation is about 10 kpc, as well as two tails that emerge from the extremes SW and NE of the main body and extend up to 41 and 58 kpc respectively. The spectral characteristics of the all observed zones are typical of H II regions of low excitation. The internal reddening is quit high, particularly in the NE nucleus. All the derived equivalent widths of the H(alpha)+[N II] lines indicate enhanced star formation compared with isolated galaxies, specially in the NE nucleus; the equivalent width corresponding to the integrated spectrum reflects starburst activity in the whole object, and is compatible with a merger of two disk galaxies. All the observed characteristics of AM 2049-691 indicate it is a merger, where a overabundance of nitrogen is detected in one of the nuclei, which has the most evolved population and would be the most massive one. The detected total IR emission is not very high. The integrated total color B - V corresponds to a Sc-Scd galaxy and its average integrated population is about F7 type. Indicative B - V colors of the nuclei, corrected for internal absorption, are in agreement with the spectroscopic results. The central radial velocity dispersions at the nuclei suggest that the most massive galaxy would be the progenitor of the SW component. The observed radial velocity curve shows the presence of two subsystems, each one associated with a different nucleus.