VLT VIMOS Integral Field Spectroscopy of the nova remnant FH Ser

Abstract: FH Ser experienced a slow classical nova outburst in February 1970 that was the first one observed at UV, optical, and IR wavelengths. Its nova remnant is elliptical in shape, with multiple knots, and a peculiar ring-like filament along its minor axis. This work aims at unveiling its true 3D spatio-kinematical structure to investigate the effects of early shaping and to assess its mass and kinetic energy using VLT VIMOS integral field spectroscopic observations. The data cube has been analyzed using 3D visualisations that reveal different structural components. FH Ser consists of a tilted prolate ellisoidal shell, most prominent in H-alpha, and a ring-like structure, most prominent in [N II]. The ellipsoidal shell has equatorial and polar velocities of 505 and 630 km/s, respectively, with its major axis tilted by 52 deg with respect to the line of sight. The inclination angle of the symmetry axis of the ring is similar, i.e., it can be described as an equatorial belt of the main ellipsoidal shell. The ionized mass is 2.6E-4 solar mass, with a kinetic energy of 1.6E45 erg. The presence of two different structural components in FH Ser with similar orientation can be linked to a density enhancement along a plane, most likely the orbital plane at the time of the nova event. The acquisition of integral field spectroscopic observations of nova remnants is most required to disentangle different structural components and to assess their 3D physical structure.