Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing
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Open Access
- 1 January 2006
- journal article
- letter
- Published by Springer Science and Business Media LLC in Nature
- Vol. 439 (7075), 437-440
- https://doi.org/10.1038/nature04441
Abstract
In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M⊕) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars1,2,3,4. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a M⊕ planetary companion at a separation of au from a M⊙ M-dwarf star, where M⊙ refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.Keywords
This publication has 23 references indexed in Scilit:
- Toward a Deterministic Model of Planetary Formation. II. The Formation and Retention of Gas Giant Planets around Stars with a Range of MetallicitiesThe Astrophysical Journal, 2004
- The Core Accretion Model Predicts Few Jovian-Mass Planets Orbiting Red DwarfsThe Astrophysical Journal, 2004
- Simulation of a Space‐based Microlensing Survey for Terrestrial Extrasolar PlanetsThe Astrophysical Journal, 2002
- The 1995 Pilot Campaign of PLANET: Searching for Microlensing Anomalies through Precise, Rapid, Round‐the‐Clock MonitoringThe Astrophysical Journal, 1998
- The Use of High‐Magnification Microlensing Events in Discovering Extrasolar PlanetsThe Astrophysical Journal, 1998
- Discovering Galactic planets by gravitational microlensing: magnification patterns and light curvesMonthly Notices of the Royal Astronomical Society, 1997
- Detecting Earth‐Mass Planets with Gravitational MicrolensingThe Astrophysical Journal, 1996
- Discovering planetary systems through gravitational microlensesThe Astrophysical Journal, 1992
- Gravitational microlensing by double stars and planetary systemsThe Astrophysical Journal, 1991
- Formation of the Terrestrial PlanetsAnnual Review of Astronomy and Astrophysics, 1980