A New Cepheid Distance Measurement and Method for NGC 6822

TL;DR

This paper introduces a new multi-band method for accurately measuring the distance to NGC 6822 using Cepheid variables, incorporating optical to mid-infrared data and a novel extinction correction technique.

Contribution

It presents a revised distance measurement to NGC 6822 with a new multi-band fitting approach and a method for extinction correction using combined data from multiple wavelengths.

Findings

Determined E(B-V)=0.35±0.04 for NGC 6822.

Measured a true distance modulus of 23.38±0.02(stat)±0.04(sys).

Developed a new multi-band extinction correction method.

Abstract

We present a revised distance to the nearby galaxy NGC6822 using a new multi-band fit to both previously published and new optical, near- and mid-infrared data for Cepheid variables. The new data presented in this study include multi-epoch observations obtained in 3.6\um and 4.5\um with the \emph{Spitzer Space Telescope} taken for the Carnegie Hubble Program. We also present new observations in J, H and \kswith FourStar on the Magellan Baade telescope at Las Campanas Observatory. We determine mean magnitudes and present new period-luminosity relations in V, I, J, H, \ks, IRAC 3.6\um and 4.5\um. In addition to using the multi-band distance moduli to calculate extinction and a true distance, we present a new method for determining an extinction-corrected distance modulus from multi-band data with varying sample sizes. We combine the distance moduli and extinction for individual stars to determine $E(B-V)=0.35\pm0.04$ and a true distance modulus $\mu_{o}=23.38\pm0.02_{stat}\pm0.04_{sys}$.