Journal Article

The Cepheid distance to the Local Group galaxy NGC 6822

Michael W. Feast, Patricia A. Whitelock, John W. Menzies and Noriyuki Matsunaga

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 421, issue 4, pages 2998-3003
Published in print April 2012 | ISSN: 0035-8711
Published online April 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20525.x
The Cepheid distance to the Local Group galaxy NGC 6822

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Recent estimates of the Cepheid distance modulus of NGC 6822 differ by 0.18 mag. To investigate this we present new multi‐epoch JHKS photometry of classical Cepheids in the central region of NGC 6822 and show that there is a zero‐point difference from earlier work. These data together with optical and mid‐infrared observations from the literature are used to derive estimates of the distance modulus of NGC 6822. A best value of 23.40 mag is adopted, based on a Large Magellanic Cloud (LMC) distance modulus of 18.50 mag. The standard error of this quantity is ∼0.05 mag. We show that to derive consistent moduli from Cepheid observations at different wavelengths, it is necessary that the fiducial LMC period–luminosity relations at these wavelengths should refer to the same subsample of stars. Such a set is provided. A distance modulus based on RR Lyrae variables agrees with the Cepheid result.

Keywords: stars: variables: Cepheids; galaxies: distances and redshifts; galaxies: individual: NGC 6822; Local Group

Journal Article.  3950 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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