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Centro de Astrofísica da Universidade do Porto

A short-period super-Earth orbiting the M2.5 dwarf GJ 3634
Detection with HARPS velocimetry and transit search with Spitzer photometry

X. Bonfils, M. Gillon, T. Forveille, X. Delfosse, D. Deming, B.-O. Demory, C. Lovis, M. Mayor, V. Neves, C. Perrier, N. C. Santos, S. Seager, S. Udry, I. Boisse, M. Bonnefoy

We report on the detection of GJ 3634b, a super-Earth of mass m sin i = 7.0+0.9-0.8 Mô and period P = 2.64561 ± 0.00066 day. Its host star is a M2.5 dwarf, has a mass of 0.45 ± 0.05 M, a radius of 0.43 ± 0.03 R and lies 19.8 ± 0.6 pc away from our Sun. The planet is detected after a radial-velocity campaign using the ESO/Harps spectrograph. GJ 3634b had an a priori geometric probability to undergo transit of ~7% and, if telluric in composition, a non-grazing transit would produce a photometric dip of ≲0.1%.We therefore followed-up upon the RV detection with photometric observations using the 4.5-µm band of the IRAC imager onboard Spitzer. Our six-hour long light curve excludes that a transit occurs for 2σ of the probable transit window, decreasing the probability that GJ 3634b undergoes transit to ~0.5%.

techniques: radial velocities - stars: late-type - planetary systems

Based on observations made with the Harps instrument on the ESO 3.6-m telescope at La Silla Observatory under program IDs 082.C-0718(B) and183.C-0437(A), and observations made with Warm Spitzer under program 60027.
Radial-velocity and photometric tables (Tables 2 and 3) are only available in electronic form at the CDS via anonymous ftp to ( or via

Astronomy and Astrophysics
Volume 528, Page A111_1
April 2011

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