2004ApJ...605L...5G

Spectroscopy and deep imaging of the group NEQ3 are presented. This system is formed by three compact objects with relative separations of ∼2".6 and ∼2".8 and a lenticular galaxy at ∼17" from the geometric center of the group. A diffuse filament is located on a line joining the three compact objects and the main galaxy. Analysis of these observations confirms the redshift previously known for three of the objects (z=0.1239 for the main galaxy, and z=0.1935 and 0.1939 for two of the compact objects). We have also determined the previously unknown redshift of the third compact object as z=0.2229. Using the relative strength and width of the main spectral lines we have classified the compact objects as two H II galaxies and one QSO (the object at z=0.1935). With cross-correlation techniques, we have tentatively estimated the redshift of the filament as z=0.19 (although a weaker component also appears at z=0.12), so that it is probably associated with the halo of the two compact objects at this redshift. The two objects at redshift ∼0.19 represent possibly one of the more clear examples of starburst (and perhaps QSO activity) driven by interaction. These considerations and the relation between these objects and the other two at reshifts ∼0.12 and ∼0.22 make the nature of the system intriguing, being difficult to explain the whole association in conventional scenarios.