For refcode 2002ApJ...565..959L: Retrieve 2 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by American Astronomical Society.
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2002ApJ...565..959L
Determination of the Distance to M33 Based on Single-Epoch I-Band Hubble
Space Telescope Observations of Cepheids
Myung Gyoon Lee and Minsun Kim
Astronomy Program, SEES, Seoul National University, Seoul 151-742, Korea;
mglee@astrog.snu.ac.kr, mskim@astro.snu.ac.kr
Ata Sarajedini
Department of Astronomy, University of Florida, P.O. Box 112055,
Gainesville, FL 32611; ata@astro.ufl.edu
and
Doug Geisler and Wolfgang Gieren
Departamento de Fisica, Grupo de Astronomia, Universidad de Concepcion,
Casilla 160-C, Concepcion, Chile; doug@kukita.cfm.udec.cl,
wgieren@coma.cfm.udec.cl
Received 2001 July 2; accepted 2001 October 4
ABSTRACT
We have determined the distance to M33 using single-epoch I-band
observations of Cepheids based on Hubble Space Telescope (HST)/Wide Field
Planetary Camera 2 (WFPC2) images of five fields in M33. Combining the
HST I-band photometry and the periods determined from the ground-based
observations (DIRECT) for 21 Cepheids with log P > 0.8 in the sample of 32
Cepheids, we derive a distance modulus of (m - M)_0_ =
24.52 +/- 0.14(random)+/-0.13(systematic) for an adopted total reddening of
M33, E(B - V) = 0.20 +/- 0.04 [E(V - I) = 0.27 +/- 0.05] given by Freedman
et al.; the reddening to the LMC, E(B - V) = 0.10; and the distance to the
LMC, (m - M)_0_ = 18.50. If the total reddening to M33 of E(B - V) =
0.10 +/- 0.09 given by Freedman, Wilson, and Madore is used, the Cepheid
distance modulus based on the I-band photometry will be increased by 0.20.
Metallicity effect on the Cepheid distance to M33 is estimated to be small,
{delta}(m - M)_Z_ = 0.01-0.06, which leads to (m - M)_0_ = 24.53-24.58
after this metallicity effect correction. Using the Wesenheit W_I_, an
extinction-free parameter, we derive a similar value, (m - M)_0_ =
24.52 +/- 0.15(random)+/-0.11(systematic). These results are in reasonable
agreement with those based on the ground-based multiepoch BVRI observations
of brighter Cepheids in M33 and are ~0.3 smaller than those based on the
tip of the red giant branch and the red clump. It is needed to estimate
better the reddening to Cepheids in M33.
Subject headings: Cepheids - galaxies: distances and redshifts - galaxies:
individual (M33, NGC 598)
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