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Gravity-Bent Starlight Reveals a New Planet
dfab writes "The first experimental proof of Einstein's general theory has been revamped to discover planets around distant stars. Yesterday astronomers announced that a new technique called gravitational microlensing has found a star that hosts a roughly Jupiter-sized planet in a roughly Jupiter-sized orbit by observing its effect on the light from a bright star beyond that planetary system. See the NASA report or the gory details."
...failed. Eddington's measurements were flawed, and the good ones weren't good enough. He was lucky. His unsupportable "result" was correct.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
This image from the "gory details" gives you a quick understanding of what they mean. Pretty cool that they use one star to see the planet around another star.
Space.com also had an article about this yesterday. It gives a little better timeline to when it will be available to check low mass stars in the future, as well as doing a comparision on other extrasolar planetary detection techniques.
actual apparent position
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earth
For those who want a quick excerpt of the science:
Gravitational microlensing uses a distant star (or other massive object) to bend light the same way as a lens would. If that star is perfectly aligned with an even more distant star (from our perspective) then the lens will call the more distant star to brighten, at least for as long as the alignment lasts.
The brightening comes with a spike (from "caustics" which are like irregularities in the lens), as the alignment gets good and them bad again. If you see a second, smaller spike, or an unusual extra image, that's evidence of a planet.
I'm not sure how you distinguish planets from weird caustics.
Note: this technique is good for detecting planets with long-period orbits, whereas the doppler-shift techniques are lousy for that, because they only work if the planet's revolution period is small (like in days).
It's been in orbit for what, two weeks or less and already we've reconfigured it for something else? Either we very efficiently proved/disproved frame dragging and moved on and I missed it or else someone screwed up royally and had to go to plan B: hey look, it can detect gravity lenses!
-- I'm not a pessimist, I'm a realist. It's not my fault that life sucks so much. --
This doesn't seem like a reliable method, because it requires a star to be right behind the one you want to find a planet around, which must be quite unlikely, unless I'm missing something.
In fact, having just scanned through the article, they do mention that problem:
"Because the effect works only in rare instances, when two stars are perfectly aligned, millions of stars must be monitored."
What keeps something from focusing the light of a bright star/nova on the Earth like sun thru a magnifying glass on an ant, and cooking the whole planet? I suppose the perfect "burn" alignment would not last long enough to do large damage.
Table-ized A.I.
Interesting. I had the idea that some star was being used to help focus light from the planet, acting as a gravitational lens and giving us a better view of the planet.
Instead, the planet is lensing some star beyond it, and then (later) so is the star that planet is around, as the planet+star moves past the object being focused.
This shows up as two sharp spikes in the brightness of the star over time (I guess one on each side of the planet, imperfectly aligned?) and one broader curve as it passes the star. The shape of the curves tell you how massive the planet and star are.
It looks like it's about Jupiter's size and a bit nearer in than Jupiter. That's comforting; thus far the only planets we ever seem to detect are bigger than Jupiter and closer than Mercury, which really boggles my mind. This system looks a lot more like ours.
Neat. What will those clever astrophysicists think of next.
.... they're looking towards the center of our galaxy, although a globular cluster might also be a good candidate.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
The first experimental proof of Einstein's general theory
I seem to recall that Einstein's General Theory of Relativity was used to explain the irregularities in observations of Mercury's orbit as it passed behind the sun, shortly after his theory was published. And using this theory explained those irregularities with a very high degree of accuracy.
"No problem. I have the capacity to do infinite work so long as you don't mind that my quality approaches zero."-Dilbert
Not really... microlensing causes an increase in the brightness of the star, not a change in the apperent position. Although you've drawn a nice picture of gravitational lensing. (see, for example, einsteins cross)
It's not wasting time, I'm educating myself.
Not really... microlensing causes an increase in the brightness of the star, not a change in the apperent position.
I'm no expert, but the gory details page notes that the microlensing event does cause a change in the apparent position (see this pic). In fact, you're seeing two distorted copies of the star.
It's just that in this case, there's not enough distance between the distorted images, so they show up as a single, brighter dot where there used to be a single, duller dot.
The AC's exaggerated angular distance can be attributed to the limitations of ASCII art. I can't find a character with an angle that small, although this is a pretty good approximation: ||
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