Erratum

Extrasolar planets and brown dwarfs around A-F type stars

V. A planetary system found with HARPS around the F6IV-V star HD 60532

M. Desort¹ - A.-M. Lagrange¹ - F. Galland¹ - H. Beust¹ - S. Udry² - M. Mayor² - G. Lo Curto³

1 - Laboratoire d'Astrophysique de Grenoble, UMR5571 CNRS, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
2 - Observatoire de Genève, Université de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
3 - European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile

A&A 491, 883-888 (2008), DOI: 10.1051/0004-6361:200810241

Abstract
The dynamical analysis in the original paper was erroneous due to a mismatch in the choice of angular parameters. The calculations had been made by assuming a pole-on () instead of an edge-on orbit. In this framework, is just the mutual inclination between the orbital planes of the two planets. We also correct some stellar parameters given in the original paper ( , [Fe/H] ).

Key words: techniques: radial velocities - stars: early-type - stars: planetary systems - stars: oscillations - stars: individual: HD 60532 - errata, addenda

	Figure 1: Orbital evolution over 100 yr of the semi-major axes (top) and eccentricities (bottom) for planets b ( left) and c (right), under their mutual perturbations, in a 3:1 resonance configuration.
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In the original paper the calculations had been made by assuming a pole-on () instead of an edge-on () orbit. The dynamical study has been made again, but this time by assuming coplanarity of the orbits, hence . The figures are changed but the main conclusions remain. Over 10⁸ yr, the planetary system is chaotic but does not indicate any instability. The semi-major axes of the two planets oscillate between 0.754 AU and 0.752 AU for planet b, and between 1.568 AU and 1.595 AU for planet c. The eccentricity of planet b oscillates between 0.118 and 0.3, and that of planet c between 0.015 and 0.141. As before, we show that, given the error bars, the secular evolution of the semi-major axis of planet b should be detectable within 10 years from now. This would constitute a strong indication of a resonant configuration. The sense of this variation is not constrained, because of the error bar on the argument of the planet c periastron. Figure 2 shows the secular evolution of the semi-major axis of planet b (a_b) in the same conditions as above, but for an initial choice of instead of . The initial evolution sense is reversed compared to Fig. 1.

As in the initial calculations, the size of the error bars in Table 2 does even not ensure that the orbital configuration is actually resonant, but here again in non resonant configurations (Fig. 4), the variations of the semi-major axis of planet b achieve a much lower amplitude than in the resonant case.

Our basic conclusions are thus unchanged: i) the resonant configuration cannot be stated, but it is probable; ii) the system is significantly chaotic; iii) in a resonant configuration, we should be able to detect semi-major axis variations in planet b's motion within 10 yrs.

Recently, a global analysis of this system by Laskar & Correia (2009) confirmed the resonant status, using numerical integration and frequency analysis. In fact, non resonant systems appear less stable than resonant ones of Gyr timescales. This further indicates a resonant configuration.

We must also correct the of the star, which is +3.83. And we can update the estimated metallicity, which is now -0.26 according to new calibrations of the data from Holmberg et al. (2007), thus slightly more metallic than before. An estimation from Gray et al. (2006) (from which we took the ) gives .

	Figure 2: Evolution of semi-major axis if planet b in the same conditions as in Fig. 1, but assuming an initial instead of .
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	Figure 3: Evolution of the 3:1 critical argument over 1000 yr, in the same condition as described in Fig. 1. We note the -libration characteristic for resonant motion.
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	Figure 4: Evolution of the semi-major axes of planet b and of the critical angle for 3:1 resonance in the same conditions as described in Fig. 1, but with ac=1.56 AU. This is a non-resonant configuration.
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We thank Daniel Fabrycky, Jacques Laskar, and Alexandre Correia for pointing out the dynamical inconsistencies of the initial version of the paper, and the referee for the stellar parameter corrections.

References

• Holmberg J., Nordström B., & Andersen J., 2007, A&A, 475, 519 [NASA ADS] [CrossRef] [EDP Sciences] (In the text)
• Laskar J., & Correia A.C.M. 2009, A&A, 496, L5 [NASA ADS] [CrossRef] [EDP Sciences] (In the text)

All Figures

	Figure 1: Orbital evolution over 100 yr of the semi-major axes (top) and eccentricities (bottom) for planets b ( left) and c (right), under their mutual perturbations, in a 3:1 resonance configuration.
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In the text

	Figure 2: Evolution of semi-major axis if planet b in the same conditions as in Fig. 1, but assuming an initial instead of .
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In the text

	Figure 3: Evolution of the 3:1 critical argument over 1000 yr, in the same condition as described in Fig. 1. We note the -libration characteristic for resonant motion.
Open with DEXTER
In the text

	Figure 4: Evolution of the semi-major axes of planet b and of the critical angle for 3:1 resonance in the same conditions as described in Fig. 1, but with ac=1.56 AU. This is a non-resonant configuration.
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In the text