Near-infrared photometry of the central stars of planetary nebulae with the VVVX survey

Abstract

Achieving accurate photometric characterizations of central stars of planetary nebulae (CSPNe) toward the galactic plane is significantly hindered by the high levels of interstellar extinction in these regions. However, near-infrared (NIR) observations offer a more effective alternative, as extinction is substantially reduced at these wavelengths. By mitigating the effects of interstellar extinction via NIR observations of the Galactic disk and bulge, we seek to improve the identification and characterization of CSPNe in these regions, enabling a deeper understanding of their properties and evolutionary status. We used NIR photometry from the VISTA Variables in the Vía Láctea (VVV) survey and its extension VVVX to define the NIR photometry of a large sample of CSPNe recently identified with Gaia EDR3 data. We explored the optical and NIR properties of all CSPNe in our sample and searched for eclipsing binary candidates among them by employing relevant catalogs. We present a homogeneous catalog of 1274 CSPNe, including their Z, Y, H, J, and K NIR magnitudes and errors. We also include our findings on the photometric properties of our sample. We report 14 CSPNe with a large IR excess indicating cool companions and/or surrounding discs and 56 eclipsing binary candidates. Based on the present VVVX CSPN catalog, we conclude that NIR photometry can prove valuable for further and in-depth studies of CSPNe. Subsequent studies ought to focus on exploring the true nature of the CSPNe that present IR excess as well as eclipsing-binary CSPNe candidates.