* Astronomy

A pair of planets around HD 202206 or a circumbinary planet?
Authors: A.C.M. Correia, S. Udry, M. Mayor, J. Laskar, D. Naef, F. Pepe, D. Queloz, N.C. Santos

(revised - OLD NEWS)


Long-term precise Doppler measurements with the CORALIE spectrograph reveal the presence of a second planet orbiting the solar-type star HD202206.
The radial-velocity combined fit yields companion masses of m_2\sini = 17.4 Jupiter masses and 2.44 Jupiter masses, semi-major axes of a = 0.83 AU and 2.55 AU, and eccentricities of e = 0.43 and 0.27, respectively.
A dynamical analysis of the system further shows a 5/1 mean motion resonance between the two planets.
This system is of particular interest since the inner planet is within the brown-dwarf limits while the outer one is much less massive.
Therefore, either the inner planet formed simultaneously in the protoplanetary disk as a superplanet, or the outer Jupiter-like planet formed in a circumbinary disk. The researchers believe this singular planetary system will provide important constraints on planetary formation and migration scenarios.





Name: HD 202206 c
M.sini: 2.44 jupiter masses
Semi-major axis: 2.55 AU
Orbital period: 1383.4 ± 18.4 d.
Eccentricity: 0.267 ± 0.021
Omega (deg): 78.99 ± 6.65
T_peri (JD-2400000): 52250.0

Name: HD 202206 b
M.sini: 17.4 jupiter masses
Semi-major axis: 0.83 AU
Orbital period: 255.87 ± 0.06 d.
Eccentricity: 0.435 ± 0.001
Omega (deg): 161.18 ± 0.30
T_peri (JD-2400000): 52250.0

The Star HD 202206
� Distance: 46.34 pc
� Spectral type: G6 V
� Apparent magnitude: V = 8.8
� Metallicity: [Fe/H] = 0.37 ± 0.07
� Mass (M_sun): M = 1.15
� Position(2000): RA = 21 14 57.7693, : DEC = -20 47 21.154

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