The first direct distance determination to a detached eclipsing binary in M33 Academic Article uri icon


  • We present the first direct distance determination to a detached eclipsing binary in M33, which was found by the DIRECT Project. Located in the OB 66 association at coordinates (, ) = (01h33 m46s.17, + 304439.9) for J2000.0, it was one of the most suitable detached eclipsing binaries found by DIRECT for distance determination, given its apparent magnitude and orbital period. We obtained follow-up BV time-series photometry, JHKs photometry, and optical spectroscopy from which we determined the parameters of the system, It contains two O7 mainsequence stars, with masses of 33.4 3.5 and 30.0 3.3 M and radii of 12.3 0.4 and 8.8 0.3 R, respectively. We derive temperatures of 37,000 1500 and 35,600 1500 K. Using BVRJHKs photometry for the flux calibration, we obtain a distance modulus of 24.92 0.12 mag (964 54 kpc), which is 0.3 mag longer than the Key Project distance to M33. We discuss the implications of our result and the importance of establishing M33 as an independent rung on the cosmological distance ladder. 2006. The American Astronomical Society. All rights reserved.

published proceedings


altmetric score

  • 19.624

author list (cited authors)

  • Bonanos, A. Z., Stanek, K. Z., Kudritzki, R. P., Macri, L. M., Sasselov, D. D., Kaluzny, J., ... Torres, G.

citation count

  • 136

complete list of authors

  • Bonanos, AZ||Stanek, KZ||Kudritzki, RP||Macri, LM||Sasselov, DD||Kaluzny, J||Stetson, PB||Bersier, D||Bresolin, F||Matheson, T||Mochejska, BJ||Przybilla, N||Szentgyorgyi, AH||Tonry, J||Torres, G

publication date

  • November 2006