The Araucaria Project. The Distance to the Small Magellanic Cloud From Late-Type Eclipsing Binaries

Abstract

We present a distance determination to the Small Magellanic Cloud (SMC) based on an analysis of four detached, long period, late type eclipsing binaries discovered by the OGLE Survey. The components of the binaries show negligible intrinsic variability. A consistent set of stellar parameters was derived with low statistical and systematic uncertainty. The absolute dimensions of the stars are calculated with a precision of better than 3%.The surface brightness -infrared color relation was used to derive the distance to each binary. The four systems clump around a distance modulus of (m − M ) = 18.99 with a dispersion of only 0.05 mag. Combining these results with the distance published by Graczyk et al. for the eclipsing binary OGLE SMC113.3 4007 we obtain a mean distance modulus to the SMC of 18.965 ± 0.025 (stat.) ± 0.048 (syst.) mag. This corresponds to a distance of 62.1 ± 1.9 kpc, where the error includes both uncertainties. Taking into account other recent published determinations of the SMC distance we calculated the distance modulus difference between the SMC and the LMC equal to 0.458 ± 0.068 mag. Finally we advocate µ SMC = 18.95 ± 0.07 as a new "canonical" value of the distance modulus to this galaxy.

The distance to the Small Magellanic Cloud from multiband period-luminosity relations for classical Cepheids and its dependence on metallicity

“…Our relative distance determination is in very good agreement with the very accurate [10] determination from late-type eclipsing binaries, which amounts to 0.472 ± 0.026 mag. Assuming that the difference between the relative distance moduli between the LMC and SMC obtained from eclipsing binaries and Cepheids is due to metallicity, we conclude that the metallicity effect on the Cepheid brightness in all bands is very small (< 0.07 mag/dex), and within the errors is consistent with zero.…”

The dependence of convective core overshooting on stellar mass

“…These objects were discovered in the course of the Optical Gravitational Microlensing Experiment (OGLE) 1 , and have served to establish a precise distance scale to those galaxies (e.g. Pietrzyński et al 2010Pietrzyński et al , 2013Graczyk et al 2012Graczyk et al , 2014. They are also ideal for our purposes because they are highly evolved.…”

Improving the surface brightness-color relation for early-type stars using optical interferometry

“…Eclipsing binary systems are particularly important to provide the zero point of the extragalactic distances and study in detail populational dependence on other distance indicators like RR Lyrae stars, Cepheids, red clump stars, etc. Thirteen long period systems composed of late-type giants were analyzed in the Magellanic Clouds so far: eight in the Large Magellanic Cloud (Pietrzyński et al 2009(Pietrzyński et al , 2013, and five in the Small Magellanic Cloud (Graczyk et al 2012(Graczyk et al , 2014. For such systems, the linear dimen- A&A 570, A104 (2014) sion of both components can be measured with a precision up to of 1% from the analysis of high-quality spectroscopic and photometric data (e.g., Torres et al 2010).…”

“…The distance to an eclipsing binary follows from the dimensions determined in this way, plus the angular diameters derived from the absolute surface brightness, which is very well calibrated for late-type stars (Di Benedetto 2005). This conceptually very simple technique very weakly depends on reddening and metallicity, and provides the most accurate tool for measuring distances to nearby galaxies (Pietrzyński et al 2013;Graczyk et al 2014).…”