Re:Free-Floating Planets May be More Common Than Stars
by wattsbaat on Wednesday May 18, 2011 @03:46PM
(#2561455)
IANA astronomer, but I believe that the typical method of planet detection relies on the assumption that planets revolve around stars. They can detect planets by measuring the tiny wobble of stars caused by the gravity of revolving planets. So I was wondering how the hell they detect free-floating (orphan) planets. The article explains that they use gravitational microlensing, which is a pretty cool technique. http://en.wikipedia.org/wiki/Gravitational_microlensing
From the article:
> A 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand is used to regularly scan the copious stars at the center of our galaxy for gravitational microlensing events. These occur when something, such as a star or planet, passes in front of another, more distant star. The passing body's gravity warps the light of the background star, causing it to magnify and brighten. Heftier passing bodies, like massive stars, will warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less.
Re:Free-Floating Planets May be More Common Than Stars
by michaelbuckbee on Wednesday May 18, 2011 @04:14PM
(#2561584)
This is far from my areas of expertise, I was hoping someone more knowledgeable might be willing to comment on whether or not this is a feasible explanation for dark matter? Thanks.
Re:Free-Floating Planets May be More Common Than Stars
by th0ma5 on Wednesday May 18, 2011 @04:33PM
(#2561672)
Not my area of expertise either, but I don't believe so. The dark matter (and energy) comes from very very large aggregate gravitational forces that are observed from galactic movement as a whole, but I think you already are aware of that, so I'm not saying anything new there, but I would certainly imagine that there would have to be a whole hell of a lot of extra-solar planets in order to account for what they're seeing, and it makes more sense (and they have presumably produced the stuff for a brief period in the lab) that there is an antithesis to matter (or energy) that is out there causing this behavior.
Basicly, there is not enough baryonic matter (stuff like protons and neutrons) in the universe to explain the observed effects of dark matter without invalidating a lot of other observations.
From the article:
> A 5.9-foot (1.8-meter) telescope at Mount John University Observatory in New Zealand is used to regularly scan the copious stars at the center of our galaxy for gravitational microlensing events. These occur when something, such as a star or planet, passes in front of another, more distant star. The passing body's gravity warps the light of the background star, causing it to magnify and brighten. Heftier passing bodies, like massive stars, will warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less.
Basicly, there is not enough baryonic matter (stuff like protons and neutrons) in the universe to explain the observed effects of dark matter without invalidating a lot of other observations.