The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 55

Abstract

We have obtained deep images in the near-infrared J and K filters of four fields in the Sculptor Group spiral galaxy NGC 55 with the ESO VLT and ISAAC camera. For 40 long-period Cepheid variables in these fields which were recently discovered by Pietrzy{ń}ski et al., we have determined mean J and K magnitudes from observations at two epochs, and derived distance moduli from the observed PL relations in these bands. Using these values together with the previously measured distance moduli in the optical V and I bands, we have determined a total mean reddening of the NGC 55 Cepheids of E(B-V)=0.127 $\pm$ 0.019 mag, which is mostly produced inside NGC 55 itself. For the true distance modulus of the galaxy, our multiwavelength analysis yields a value of 26.434 $\pm$ 0.037 mag (random error), corresponding to a distance of 1.94 $\pm$ 0.03 Mpc. This value is tied to an adopted true LMC distance modulus of 18.50 mag. The systematic uncertainty of our derived Cepheid distance to NGC 55 (apart from the uncertainty on the adopted LMC distance) is $\pm$4%, with the main contribution likely to come from the effect of blending of some of the Cepheids with unresolved companion stars. The distance of NGC 55 derived from our multiwavelength Cepheid analysis agrees within the errors with the distance of NGC 300, strengthening the case for a physical association of these two Sculptor Group galaxies.

latex. ApJ accepted

References in corpus (5)

• A new calibration of Galactic Cepheid Period-Luminosity relations from B to K bands, and a comparison to LMC PL relations
• Cepheid Parallaxes and the Hubble Constant
• The Araucaria Project: Distance to the Local Group Galaxy NGC 3109 from Near-Infrared Photometry of Cepheids
• The Araucaria Project. The Distance to the Sculptor Group Galaxy NGC 55 from a Newly Discovered Abundant Cepheid Population
• Nonlinear Period-Luminosity Relation for the Large Magellanic Cloud Cepheids: Myths and Truths

Cited by in corpus (11)

• The Araucaria Project. The Distance to the Sculptor dwarf spheroidal galaxy from infrared photometry of RR Lyrae stars
• A spectroscopic study of blue supergiant stars in the Sculptor galaxy NGC 55: chemical evolution and distance
• The Araucaria Project. The Distance of the Large Magellanic Cloud from Near-Infrared Photometry of RR Lyrae Variables
• A Council of Giants
• The Araucaria Project. The Distance to the Sculptor Galaxy NGC 247 from Near-Infrared Photometry of Cepheid Variables
• The Araucaria Project. The Distance to the Local Group Galaxy WLM from Near-Infrared Photometry of Cepheid Variables
• The Araucaria Project: VLT-spectroscopy of blue massive stars in NGC 55
• The Araucaria Project. The Distance to the Local Group Galaxy WLM from Cepheid Variables discovered in a Wide-Field Imaging Survey
• The Araucaria Project. Distances to Nine Galaxies Based on a Statistical Analysis of their Carbon Stars (JAGB Method)
• The Araucaria Project: The Distance to the Sculptor Group Galaxy NGC 247 from Cepheid Variables Discovered in a Wide-Field
• Extra-galactic distances with massive stars: the role of stellar variability in the case of M33