(October 17, 2012 at 4:49 pm)Welsh cake Wrote: Its plausible then that we haven't discovered any actual exoplanets, just really big brown dwarfs.
Very few discovered explanets have an upper constraint on mass that fits models of brown dwarfs.
(October 17, 2012 at 4:49 pm)Welsh cake Wrote: The cosmos must have planets orbiting stars, and rogue planets, in their abundance...
I don't recall where I read it, but it's been estimated that there could be hundreds of billions of rogue planets in the Milky Way alone.
http://en.wikipedia.org/wiki/Rogue_planet#Observation Wrote:When a planetary-sized object passes in front of a background star, its gravitational field causes a momentary increase in the visible brightness of the background star. This is known as microlensing. Astrophysicist Takahiro Sumi of Osaka University in Japan and colleagues, who form the Microlensing Observations in Astrophysics (MOA) and the Optical Gravitational Lensing Experiment (OGLE) collaborations, carried out a study of microlensing which they published in 2011. They observed 50 million stars in our galaxy using the 1.8 meter MOA-II telescope at New Zealand's Mount John Observatory and the 1.3 meter Warsaw University Telescope at Chile's Las Campanas Observatory. They found 474 incidents of microlensing, just 10 of which were brief enough to be planets of around Jupiter's size with no associated star in the immediate vicinity. The researchers estimated from their observations that there are nearly two free-floaters for every star in our galaxy.[6][7][8] Other estimations suggest a much larger number, up to 100,000 times more free-floating planets than stars in our Milky Way. [9]
