The Araucaria Project. The Distance to the Sculptor Group Galaxy NGC 55 from a Newly Discovered Abundant Cepheid Population

Abstract

We have detected, for the first time, Cepheid variables in the Sculptor Group SB(s)m galaxy NGC 55. From wide-field images obtained in the optical V and I bands during 77 nights in 2002-2003, we have found 143 Cepheids with periods ranging from 5.6 to 175.9 days. 133 of these objects have periods longer than 10 days, making NGC 55 to-date the galaxy with the largest known number of long-period Cepheids in the Sculptor Group. We construct period-luminosity relations from our data and obtain distance moduli corrected for the small foreground reddening to NGC 55 of 26.79 $\pm$ 0.04 mag (internal error) in V, 26.66 $\pm$ 0.03 mag in I and 26.40 $\pm$ 0.05 mag in the reddening-independent V-I Wesenheit index. The trend of increasing distance moduli with shorter wavelength hints at the existence of significant reddening intrinsic to NGC 55 which affects the measured Cepheid magnitudes. From our data, we determine the intrinsic mean reddening of the Cepheids in NGC 55 as E(B-V) = 0.102 mag which brings the distance determinations from the different bands into excellent agreement. Our best distance estimate for NGC 55 from the present optical Cepheid photometry is 26.40 mag $\pm$ 0.05 mag (internal error) $\pm$ 0.09 mag (systematic error). This value is tied to an assumed LMC distance of 18.50 mag. Our quoted systematic error of the present NGC 55 Cepheid distance does not take into account the current uncertainty on the distance of the fiducial LMC galaxy itself. Within the small respective uncertainties, the Sculptor Group galaxies NGC 55 and NGC 300 are at the same distance of 1.9 Mpc, strengthening the case for a physical association of these galaxies

arXiv commentAstronomical Journal in press (December issue)

References in corpus (16)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Distances to Nearby Galaxies in Sculptor
• Cepheid Distances to SNe Ia Host Galaxies based on a Revised Photometric Zero-Point of the HST-WFPC2 and New P-L Relations and Metallicity Corrections
• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 300
• The effect of metallicity on the Cepheid Period-Luminosity relation from a Baade-Wesselink analysis of Cepheids in the Galaxy and in the Small Magellanic Cloud
• Direct Distances to Cepheids in the Large Magellanic Cloud: Evidence for a Universal Slope of the Period-Luminosity Relation up to Solar Abundance
• The Araucaria Project. The Distance to the Local Group Galaxy IC 1613 from Near-Infrared Photometry of Cepheid Variables
• The Araucaria Project. The Distance to the Local Group Galaxy NGC 6822 from Cepheid Variables discovered in a Wide-Field Imaging Survey
• The Araucaria Project: Distance to the Local Group Galaxy NGC 3109 from Near-Infrared Photometry of Cepheids
• Star formation in gaseous galaxy halos: VLT-spectroscopy of extraplanar HII-regions in NGC55
• The Araucaria Project: The effect of blending on the Cepheid distance to NGC 300 from Advanced Camera for Surveys images
• The Araucaria Project. An improved distance to the Sculptor spiral galaxy NGC 300 from its Cepheid variables
• Photometric standard stars in the BVI system in a wide field centered on the spiral galaxy NGC 300
• The Araucaria Project. A Wide-Field Photometric Survey for Cepheid Variables in NGC 3109
• The Hubble Constant from Type Ia Supernova Calibrated with the Linear and Non-Linear Cepheid Period-Luminosity Relation
• The Araucaria Project. Bright Variable Stars in NGC 6822 from a Wide-Field Imaging Survey

Cited by in corpus (28)

• Insights into the Cepheid distance scale
• Absolute-Magnitude Distributions of Supernovae
• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 300
• Taking the Measure of the Universe: Precision Astrometry with SIM PlanetQuest
• Characteristics of the Galaxy according to Cepheids
• On the distance of the globular cluster M4 (NGC 6121) using RR Lyrae stars: I. optical and near-infrared Period-Luminosity and Period-Wesenheit relations
• Gas and dark matter in the Sculptor group: NGC 300
• Comparison of Distances from RR Lyrae Stars, the Tip of the Red-Giant Branch and Classical Cepheids
• Radio haloes in nearby galaxies modelled with 1D cosmic-ray transport using SPINNAKER
• The ARAUCARIA project: Grid-Based Quantitative Spectroscopic Study of Massive Blue Stars in NGC55
• A spectroscopic study of blue supergiant stars in the Sculptor galaxy NGC 55: chemical evolution and distance
• The Araucaria Project. The Distance to the Sculptor Galaxy NGC 247 from Near-Infrared Photometry of Cepheid Variables
• The Araucaria Project. First Cepheid Distance to the Sculptor Group Galaxy NGC 7793 from Variables discovered in a Wide-Field Imaging Survey
• Using Ultra Long Period Cepheids to Extend the Cosmic Distance Ladder to 100 Mpc and Beyond
• The Environmental Influence on the Evolution of Local Galaxies
• The Araucaria Project: VLT-spectroscopy of blue massive stars in NGC 55
• The Araucaria Project. Near-Infrared Photometry of Cepheid Variables in the Sculptor Galaxy NGC 55
• The Araucaria Project. The Distance to the Local Group Galaxy WLM from Cepheid Variables discovered in a Wide-Field Imaging Survey
• Stellar metallicities beyond the Local Group: the potential of J-band spectroscopy with extremely large telescopes
• Gas and dark matter in the Sculptor group: NGC 55
• Ultra Long Period Cepheids: a primary standard candle out to the Hubble flow
• A Chandra Observation of the Nearby Sculptor Group Sd Galaxy NGC 7793
• Physical properties of the first spectroscopically confirmed red supergiant stars in the Sculptor Group galaxy NGC 55
• LBT Discovery of a Yellow Supergiant Eclipsing Binary in the Dwarf Galaxy Holmberg IX
• The Araucaria Project: The Distance to the Sculptor Group Galaxy NGC 247 from Cepheid Variables Discovered in a Wide-Field
• First VLT/X-shooter spectroscopy of early-type stars outside the Local Group
• Asteroseismology, standard candles and the Hubble Constant: what is the role of asteroseismology in the era of precision cosmology?
• Pulsating variables from the OGLE and Araucaria projects