5 Conclusions

The integral field spectroscopic observations presented in this paper clearly reveal that Th2-A, which is known to have a thick ring structure, in fact has also a pair of thin bipolar outflows. We have produced the spatially resolved maps of the H$\alpha$ emission line, including flux intensity and radial velocity (see Fig.2). In addition, we have derived the flux intensity maps of the H$\alpha$ emission line observed at different velocity channels (see Fig.3). These observations suggest that Th2-A has an equatorial ring structure with a pair of collimated bipolar outflows along its symmetric axis.

We modeled the observed velocity channels using the 3D interactive tool SHAPE. The geometrical components included in the model are a thick toroidal shell and a thin prolate ellipsoid. From the reconstruction model, the nebula is found to be tilted by $i=-10^{\circ} \pm 5^{\circ}$ with respect to the line of sight, while its symmetry axis is measured to be P.A. $=-45^{\circ} \pm 5^{\circ}$ from the north toward the east in the ECS. It is found that the dense shell has an expansion velocity of $40\pm10$kms${}^{-1}$, while the collimated bipolar outflows reach an expansion velocity of $90\pm20$kms$^{-1}$.

The high-resolution imaging of the central region of Th2-A shows the presence of two stars: CSPN and late-type star (Ciardullo et al., 1999; Weidmann et al., 2008). However, a binary system with a separation of $1$$\mbox{$.\!\!^{\prime\prime}$}$$4$ (see Fig. 1) unlikely contributes to the formation of its point-symmetric outflows. Previously, morpho-kinematic modeling of some PNe around close-binary systems have been shown to have alignments between the nebular shells and the binary orbital inclinations (see e.g. Mitchell et al., 2007; Jones et al., 2010; Huckvale et al., 2013; Tyndall et al., 2012; Jones et al., 2012). A closer inspection of the CSPN Th2-A is necessary to examine the existence of an undiscovered companion. A potential triple system could have important implications for its morpho-kinematic structure and rare [WO]-type CSPN. Results of the present study, together with future in-depth studies of its central stars, will help us understand the possible role of close-binary systems in PN morphology.