A ~5 M⊕ Super-Earth Orbiting GJ 436? The Power of Near-Grazing Transits
Abstract
Most of the presently identified exoplanets have masses similar to that of Jupiter and therefore are assumed to be gaseous objects. With the ever-increasing interest in discovering lower mass planets, several of the so-called super-Earths (1 M⊕ < M < 10 M⊕), which are predicted to be rocky, have already been found. Here we report the possible discovery of a planet around the M-type star GJ 436 with a minimum mass of 4.7 ± 0.6 M⊕ and a true mass of ~5 M⊕, which would make it the least massive planet around a main-sequence star found to date. The planet is identified from its perturbations on an inner Neptune-mass transiting planet (GJ 436b), by pumping eccentricity and producing variations in the orbital inclination. Analysis of published radial velocity measurements indeed reveals a significant signal corresponding to an orbital period that is very close to the 2:1 mean motion resonance with the inner planet. The near-grazing nature of the transit makes it extremely sensitive to small changes in the inclination.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2008
- DOI:
- 10.1086/587961
- arXiv:
- arXiv:0801.3230
- Bibcode:
- 2008ApJ...677L..59R
- Keywords:
-
- planetary systems;
- planetary systems: formation;
- stars: individual: GJ 436;
- Astrophysics
- E-Print:
- 5 pages, 3 figures, accepted for publication in The Astrophysical Journal Letters
