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Astron. Astrophys. 351, 398 (1999)

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X rays from old open clusters: M 67 and NGC 188

T. Belloni 1, F. Verbunt 2 and R.D. Mathieu 3

1 Astronomical Institute "Anton Pannekoek", University of Amsterdam and Center for High-Energy Astrophysics, Kruislaan 403,
1098 SJ Amsterdam, The Netherlands
2 Astronomical Institute, P.O.Box 80000, 3508 TA Utrecht, The Netherlands
3 Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA

Astron. Astrophys. (1998) 339, 431-439

The correct [FORMULA] colour of Sanders 628, the suggested counterpart of X-ray source no. 35 in Table 1 of Belloni et al. (1998) is [FORMULA]. The location of the counterpart thus is close to the main sequence. The suggestion in Table 3 of Belloni et al. (1998) that the source is a cataclysmic variable is no longer viable; it is more likely to be a RS CVn type system.

The corrected version of Fig. 1 is shown.

[FIGURE] Fig. 1. HR diagram of M 67 in which the stars detected in X rays are indicated with special symbols. The size of a symbol is proportional to the logarithm of the X-ray luminosity in the 0.1-2.4 keV band in erg s-1. The shape of a symbol indicates its spectroscopic binary status. Filled circles and triangles indicate circular binaries and eccentric binaries (i.e. eccentricity larger than 3-[FORMULA]), respectively, squares indicate binaries with unknown period, and crosses indicate objects for which there is no indication of binarity. Note that for the binaries we show the total magnitude and colour.

Present address: Osservatorio astronomico di Brera, Via E. Bianchi 46, 23807, Merate (LC), Italy

Send offprint requests to: T. Belloni (belloni@merate.mi.astro.it)

© European Southern Observatory (ESO) 1999

Online publication: November 2, 1999