Tests of the Galactic planetary nebula distance scale with the initial Gaia parallax distances of their central stars

TL;DR

This study uses Gaia DR1 data to evaluate and calibrate Galactic planetary nebula distance scales, finding promising potential for future Gaia data releases to improve distance measurements.

Contribution

First assessment of Gaia DR1 parallaxes for central stars of planetary nebulae, testing and validating existing distance scales with initial Gaia data.

Findings

Good correlation between Gaia parallaxes and other distance estimates.

Gaia parallaxes are slightly lower (~0.1 dex) than previous measurements.

Future Gaia data releases hold promise for recalibrating PN distance scales.

Abstract

We used the "primary dataset" of Gaia Data Release 1 (DR1) to search for parallax measurements of central stars (CSs) of Galactic planetary nebulae (PNe), to determine PN distances. We found that a trigonometric parallax is available for 16 CSs, seven of which with relative uncertainty below 80%. The limited comparison of these trigonometric distances to other reliable individual determinations discloses good correlation between the two sets, with the Gaia parallax distances being lower by a factor of ~0.1 dex in the logarithmic distances. We tested with the Gaia parallaxes the most popular Galactic PN distance scales, namely, the physical radius vs. surface brightness, and the ionized mass vs. inverse optical thickness scales. While the number of available calibrators may still be too low, and their relative uncertainties too high, to derive a working distance scale, we were able to assess the current sample and to reveal the very promising potential of the future Gaia releases for a recalibration of the distance scale of Galactic PNe.