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Astron. Astrophys. 358, L5-L8 (2000)


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Letter to the Editor

A search for Jovian-mass planets around CM Draconis using eclipse minima timing

H.J. Deeg 1,2, L.R. Doyle 3, V.P. Kozhevnikov 4, J.E. Blue 5, E.L. Martín 6 and J. Schneider 7

1 Instituto de Astrofísica de Andalucía, Granada, Spain (hdeeg@bigfoot.com)
2 Instituto de Astrofísica de Canarias, 38200 La Laguna (Tenerife), Spain
3 SETI Institute, 2035 Landings Drive, Mountain View, CA 94043, USA (ldoyle@seti.org)
4 Ural State University, Astronomical Observatory, Lenin ave. 51, Ekaterinburg 620083, Russia (valerij.kozhevnikov@usu.ru)
5 SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025, USA
6 Division of Geology and Planetary Sciences, Caltech MC 150-21, Pasadena, CA 91125, USA
7 CNRS-Observatoire de Paris, 92195 Meudon, France

Received 17 March 2000 / Accepted 2 May 2000

Abstract

For the eclipsing binary system CM Draconis, eclipse minimum times have been monitored with high precision between 1994 and 1999. Periodic deviations of minimum times from a linear ephemeris may indicate the presence of an orbiting third body. Individual measurements of 41 eclipse minimum times result in a standard deviation from linear ephemeris of 5.74 seconds. A power spectral analysis of the residuals reveals only one periodicity with more then 2 seconds amplitude. This feature, with a periodicity between 750 and 1050 days has an amplitude of 2.8[FORMULA]0.5 seconds, and is also present with similar phases if the power spectral analysis is performed independently for primary and secondary eclipses. It would be compatible with a circumbinary planet of 1.5 -3 Jupiter masses at an orbital distance of 1.1-1.45 AU to the binary barycenter. The assignation of a planet to the CM Dra system can however only be upheld if this periodicity can be followed in future observations for several years. For low-mass eclipsing binary stars, the method of eclipse minimum timing allows one to reach mass limits for the detection of third bodies well below that feasible by radial velocity measurements.

Key words: eclipses – stars: binaries: eclipsing – stars: individual: CM Dra – stars: low-mass, brown dwarfs – stars: planetary systems

Send offprint requests to: H.J. Deeg

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000

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