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

TL;DR

The paper tackles the difficulty of characterizing central stars of planetary nebulae (CSPNe) in the Galactic plane due to heavy extinction by leveraging near-infrared (NIR) data from the VVV and VVVX surveys. By crossmatching VVV/VVVX photometry with Gaia EDR3 CSPN identifications, the authors assemble a homogeneous catalog of 1274 CSPNe with Z, Y, J, H, and Ks magnitudes, enabling a comprehensive analysis of their optical and NIR properties. They identify 14 CSPNe with significant IR excess suggestive of cool companions or circumstellar disks and 56 eclipsing-binary CSPNe candidates by combining multiple variability and Gaia-based catalogs. The study demonstrates the value of NIR photometry for CSPNe research, offering a robust dataset for investigating binarity and circumstellar environments and guiding future follow-up observations to elucidate the nature of IR-excess and eclipsing-binary CSPNe.

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.

Figures (15)

• Figure 1: Map of the Gonzalez-Santamaria et al. (2021) CSPNe matched with the VVV survey (red circles) and with the VVVX survey (blue circles).
• Figure 2: Comparison of the VVV vs VVVX samples matched CSPNe from Gonzalez-Santamaria et al. (2021), displaying the optical and NIR CMDs and color-color diagram for the VVV survey (red circles) and the VVVX survey (blue circles).
• Figure 3: CSPNe of Gonzalez-Santamaria et al. (2021) matched with the VVV and VVVX survey (red circles), compared with the unmatched original sources (grey crosses).
• Figure 4: Optical CMD and magnitude dependence on extinction distribution of the CSPN AB (red) and C (blue) subsamples.
• Figure 5: Comparison with all matched Gonzalez-Santamaria et al. (2021) CSPNe, including the group AB (red) vs group C (magenta). Note: all sources without Gaia optical colors have been assigned to $BP-RP=0.0$ mag.