EDP Sciences
Free access
Volume 417, Number 2, April II 2004
Page(s) 689 - 693
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20031741

A&A 417, 689-693 (2004)
DOI: 10.1051/0004-6361:20031741

IO Aqr: Twins just at turn off?

W. Dimitrov1, D. Kolev2 and A. Schwarzenberg-Czerny1, 3

1  Astronomical Observatory of Adam Mickiewicz University, ul. Sloneczna 36, 60-286 Poznan, Poland
2  National Astronomical Observatory Rozhen, PO Box 136, 4700 Smolyan, Bulgaria
    e-mail: dzkolev@abv.bg
3  Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa, Poland
    e-mail: alex@camk.edu.pl

(Received 22 April 2003 / Accepted 8 December 2003)

We present photometric and spectroscopic analysis of the eclipsing binary IO Aqr with orbital period $2\fd37$. The system is detached, with similar almost spherical components. The star is classified as G0 spectral type. In the analysis we have used spectra obtained at a 2-m telescope with a Coudé spectrograph for two regions NaD and H $_\alpha$, as well as ASAS I band photometry and R, V photometry obtained at a 0.4 m telescope. The model of the star was obtained using a code based on the Wilson-Devinney method. The radii of the stars for our best fit are $R_1=2.09\pm0.13~R_{\odot}$ and $R_2=2.54\pm0.06~R_{\odot}$ while the masses of the components are $M_1=1.53\pm0.02~M_{\odot}$ and $M_2=1.64\pm0.02~M_{\odot}$. Both components are slightly evolved main sequence stars.

Key words: eclipsing binaries -- binaries: spectroscopic -- stars: individual: IO Aqr

Offprint request: W. Dimitrov, dimitrov@amu.edu.pl

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