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Absolute Dimensions and Distance Modulus for HV 2226 in the SMC

Published online by Cambridge University Press:  07 August 2017

S.A. Bell
Affiliation:
Department of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY169SS, Scotland
G. Hill
Affiliation:
Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, R.R. No. 5, Victoria, B. C., Canada, V8×4M6
R.W. Hilditch
Affiliation:
Department of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY169SS, Scotland
J.V. Clausen
Affiliation:
Copenhagen University Observatory, Brorfeldevej 23, DK-4340, Tølløse, Denmark
A.P. Reynolds
Affiliation:
Department of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY169SS, Scotland
A. Giménez
Affiliation:
Laboratorio de Astrofísica Espacial y Física Fundamental, Instituto Nacional de Técnica Aerospacial, Apdo. 50727-28080 Madrid, Spain

Abstract

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Absolute dimensions and the distance modulus have been established for the early-type eclipsing binary HV 2226 in the SMC. Analyses of the new radial velocities reported here, and CCD light curves published by Jensen et al. (1988) yield component masses of 9.3 ± 0.7 and 5.6 ± 0.5 M, respectively. The radii are 5.6 ± 0.2 and 5.3 ± 0.2 R with the secondary component filling its Roche lobe which implies that HV 2226 must have evolved through a case A mass-transfer process. A distance modulus of (mv Mv )0 = 18m.6 ± 0m.3 is derived, marginally lower than the adopted mean of 18m.9 for the SMC. The position of HV 2226, however, indicates that it is in fact situated in the near side of the SMC. In the present case, the accuracy of this estimate is limited mainly by the uncertainties of ≈ 2000 K in the effective temperatures. We point out that distance moduli with uncertainties of ± 0m.15 can be achieved from accurate radial velocities, light curves and colour indices of eclipsing binaries; such systems in the SMC and LMC are therefore promising distance indicators and work on further selected candidates is in progress.

Type
Oral and Contributed Papers
Copyright
Copyright © Kluwer 1992 

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