The two central stars of NGC 1514: can they actually be related?

TL;DR

This study investigates whether the two bright stars at the center of NGC 1514 are physically related, using spectroscopic data to determine their velocities and possible association.

Contribution

The paper provides evidence that the two central stars are not gravitationally bound, challenging previous assumptions of a binary system in NGC 1514.

Findings

The radial velocities of the two stars differ by 13 km/s.

The velocities have remained unchanged over 500 days.

The cooler star is likely a chance alignment, not part of a binary system.

Abstract

The central star of the planetary nebula NGC 1514 is among the visually brightest central stars in the sky (V=9.5). It has long been known to show a composite spectrum, consisting of an A-type star and a much hotter star responsible for the ionization of the surrounding nebula. These two stars have always been assumed to form a binary system. High-resolution spectrograms obtained with Espadons at the CFHT on Mauna Kea have allowed to measure good radial velocities for both stars. They differ by 13 $\pm$ 2 km s$^{-1}$. The stellar velocities have not changed after 500 days. We have also estimated the metallicity of the cooler star. Combining these data with other information available in the literature, we conclude that, unless all the published nebular radial velocities are systematically wrong, the cooler star is just a chance alignment, and the two stars are not orbiting each other. The cooler star cannot have played any role in the formation of NGC 1514.