On the eclipsing nature of

L. M. Freyhammer; J. V. Clausen; T. Arentoft; C. Sterken

doi:10.1051/0004-6361:20010194

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Volume 369 / No 2 (April II 2001)

A&A, 369 2 (2001) 561-573

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Issue		A&A Volume 369, Number 2, April II 2001


Page(s)		561 - 573
Section		Interstellar and circumstellar matter
DOI		https://doi.org/10.1051/0004-6361:20010194
Published online		15 April 2001

A&A 369, 561-573 (2001)

On the eclipsing nature of $\mathsf{CPD-59\degr2628}$ ^*

L. M. Freyhammer¹^,2, J. V. Clausen³, T. Arentoft¹ and C. Sterken¹

¹ University of Brussels (VUB), Pleinlaan 2, 1050 Brussels, Belgium
² Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
³ Niels Bohr Institute for Astronomy, Physics and Geophysics; Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark

Corresponding author: L. M. Freyhammer, lfreyham@vub.ac.be

Received: 9 August 2000
Accepted: 24 January 2001

Abstract

The spectroscopic binary CPD -59°2628 (Sp = O9.5 V) has been discovered to be a detached eclipsing binary, and we present an analysis based on new light curves, published spectroscopy and two new high-resolution spectra. uvby light curves from more than 2000 observations are analysed with the WINK and the Wilson-Devinney (WD) programs. Geometric distortions and photometric effects from the proximity of the components are included in the computations. The detached system has a close circular orbit of high inclination and high maximum projected velocities. We find a photometric period $P=1\fd47$ which is consistent with the spectroscopy-binary period by Solivella & Niemela ([CITE]). We use this period to rematch the misidentified radial velocities from Levato et al. ([CITE]) and apply them in an analysis using the method of Lehmann-Filhes. We find that CPD -59°2628 is a young system close to the ZAMS. Its distance is $2.6\pm0.1$ kpc and it has a systemic velocity of -19 km s^-1, confirming its membership in the cluster Trumpler 16 (radial velocity -23.5 km s^-1). The temperatures are 32 000 K for the hotter star (A) and 30 000 K for the cooler (B). We determine the absolute dimensions (solar units): $M_A=14.0\pm2.0$ , $R_A=5.29\pm0.26$ , $M_B=11.7\pm1.8$ and $R_B=4.38\pm0.22$ . By adopting $E(b-y)=0.306$ , we get $M_{{\rm bol},A}=-6.3\pm0.1$ , $M_{V,A}=-3.2\pm0.1$ , $M_{{\rm bol},B}=-5.6\pm0.1$ and $M_{V,B}=-2.7\pm0.1$ . Theoretical stellar models from Claret ([CITE]), including convective-core overshooting and mass loss for a composition ( $X=0.70$ , $Z=0.02$ ), appear to fit the components at an age of ~2 Myr.

Key words: stars: individual: CPD -59°2628 / stars: binaries: spectroscopic / stars: binaries: eclipsing / stars: distances / stars: early-type

^*

Based on observations obtained at the European Southern Observatory at La Silla, Chile (Applications 62H-0110, 62H-0110 and 64.L-0031) and the South African Astronomical Observatory, Sutherland, South Africa.

© ESO, 2001

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On the eclipsing nature of *

On the eclipsing nature of $\mathsf{CPD-59\degr2628}$ ^*