A Cepheid-Based Distance to the Seyfert Galaxy NGC 6814

TL;DR

This paper measures the distance to galaxy NGC 6814 using Cepheid variable stars observed with the Hubble Space Telescope, providing a precise distance estimate crucial for understanding galaxy properties.

Contribution

The study presents a new Cepheid-based distance measurement to NGC 6814, utilizing extensive HST observations and identifying 90 Cepheid candidates, refining galaxy distance estimates.

Findings

Distance to NGC 6814 is 21.65 Mpc with 0.41 Mpc uncertainty.

Identified 90 Cepheid candidates with periods 13-84 days.

Distance modulus relative to LMC is 13.200 mag.

Abstract

We present a Cepheid-based distance to the nearby Seyfert galaxy NGC\,6814 from {\it Hubble Space Telescope} observations. We obtained F555W and F814W imaging over the course of 12 visits with logarithmic time spacing in 2013 August$-$October. We detected and made photometric measurements for 16,469 unique sources across all images in both filters, from which we identify 90 excellent Cepheid candidates spanning a range of periods of $13-84$ days. We find evidence for incompleteness in the detection of candidates at periods <21 days. Based on the analysis of Cepheid candidates above the incompleteness limit, we determine a distance modulus for NGC\,6814 relative to the LMC of $\mu_{\rm rel\,LMC}=13.200^{+0.031}_{-0.031}$ mag. Adopting the recent constraint of the distance modulus to the LMC determined by Pietrzynski et al., we find $m-M=31.677^{+0.041}_{-0.041}$ which gives a distance of $21.65 \pm 0.41$ Mpc to NGC 6814.