TY  - JOUR
A1  - Beaulieu, Jean-Philippe
A1  - Bennett, David P.
A1  - Fouqué, Pascal
A1  - Williams, Andrew
A1  - Dominik, Martin
A1  - Jorgensen, Uffe Grae
A1  - Kubas, Daniel
A1  - Cassan, Arnaud
A1  - Coutures, Christian
A1  - Greenhill, John
A1  - Hill, Kym
A1  - Menzies, John
A1  - Sackett, Penny D.
A1  - Albrow, Michael D.
A1  - Brillant, Stephane
A1  - Caldwell, John A. R.
A1  - Calitz, Johannes Jacobus
A1  - Cook, Kem H.
A1  - Corrales Cosmeli, Esperanza de Santa Cecilia
A1  - Desort, Morgan
A1  - Dieters, Stefan
A1  - Dominis, Dijana
A1  - Donatowicz, Jadzia
A1  - Hoffman, Martie
A1  - Kane, Stephen R.
A1  - Marquette, Jean-Baptiste
A1  - Martin, Ralph
A1  - Meintjes, Pieter
A1  - Pollard, Karen R.
A1  - Sahu, Kailash C.
A1  - Vinter, Christian
A1  - Wambsganss, Joachim
A1  - Woller, Kristian
A1  - Horne, Keith
A1  - Steele, Iain
A1  - Bramich, Daniel M.
A1  - Burgdorf, Martin
A1  - Snodgrass, Colin
A1  - Bode, Mike
A1  - Udalski, Andr
T1  - Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing
N2  - 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 stars(1-4). 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 5.5(-2.7)(+5.5)M(+) planetary companion at a separation of 2.6(- 0.6)(+1.5) AU from a 0.22(-0.11)(+0.21)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.
Y1  - 2006
UR  - http://www.nature.com/nature/
U6  - https://doi.org/10.1038/Nature04441
SN  - 0028-0836
ER  -