EDP Sciences
Free access
Volume 405, Number 3, July III 2003
Page(s) 1063 - 1074
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030643

A&A 405, 1063-1074 (2003)
DOI: 10.1051/0004-6361:20030643

The massive binary CPD - 41° 7742 I. High-resolution optical spectroscopy

H. Sana1, H. Hensberge2, G. Rauw1 and E. Gosset1

1  Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17, Bât. B5c, 4000 Liège, Belgium
    e-mail: sana@astro.ulg.ac.be
2  Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
    e-mail: Herman.Hensberge@oma.be

(Received 28 February 2003 / Accepted 23 April 2003 )

We present the results of a spectroscopic campaign on the early-type binary CPD - 41° 7742. For the first time, we unambiguously detect the secondary's spectral signature and derive an accurate orbital solution for both components of the system. We confirm that the orbit displays a slight but definite eccentricity ( $e=0.027\pm0.006$) despite the short period ( $P=2.44070\pm0.00043$ days). Previous radial velocity measurements available in the literature constitute together with our new observations a data set that spans more than 30 years. The combined primary orbital solution inferred is in excellent agreement with our solution and gives a period $P=2.44062\pm0.00005$ days. Based on spectroscopic criteria, we derive a spectral and luminosity classification of O9 III + B1 III. However, the luminosities and radii inferred from the membership of NGC 6231 rather indicate lower luminosity classes. We show that the equivalent widths of well isolated primary lines display variations that suggest that CPD - 41° 7742 is an eclipsing binary. This makes CPD - 41° 7742 the second known SB2 eclipsing early-type binary of the NGC 6231 cluster. We approximately constrain the inclination of the system $i_\mathrm{min}\approx60\degr$. This may indicate that the system does not offer enough room for two stars with radii typical of giant stars and lends further support to a less evolved luminosity classification for at least one of the objects.

Key words: stars: individual: CPD - 41° 7742 -- stars: binaries: close -- stars: binaries: spectroscopic -- stars: early-type -- stars: fundamental parameters

Offprint request: H. Sana, sana@astro.ulg.ac.be

SIMBAD Objects

© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.