Gravity-Bent Starlight Reveals a New Planet 26
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."
"The first experimental proof" (Score:4, Interesting)
Interesting (Score:5, Interesting)
More Info (Score:5, Informative)
I can draw this stroy. Neat, huh? (Score:2, Funny)
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earth
Re:I can draw this stroy. Neat, huh? (Score:3, Informative)
Re:I can draw this stroy. Neat, huh? (Score:2)
I'm no expert, but the gory details page [princeton.edu] notes that the microlensing event does cause a change in the apparent position (see this pic [princeton.edu]). 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 angula
How it works (Score:5, Informative)
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).
Re:What happened to the original experiment? (Score:2, Informative)
As far as I know, the satellite you're thinking of has to sit up there for a few months yet, so that we can see if it's moved by a few gazillionths of a millimetre or something - I can hardly wait!
Re:What happened to the original experiment? (Score:4, Informative)
Re:What happened to the original experiment? (Score:3, Informative)
Not only is it going to take 1-2 years to test the theory, it hasn't been launched yet. It's new\rescheduled launch date isn't till April 19, 2004.
So to answer your question of what happened to the results??
It's hard to give results on a project that hasn't been launched yet.
Read more about this project here. [stanford.edu]
Lucky (Score:3, Informative)
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."
There's a reason (Score:3, Insightful)
Re:Lucky (Score:1)
Projects like the OGLE surveys sample many millions of objects many times: just to produce this sort of variability data. Its not a question of reliably finding the objects during an observation, but more being able to identify them when they do occur, throughout a long sequence of observations.
Re:Lucky (Score:2)
Well, since the guys who found this [astrouw.edu.pl] say that: "In the 2004 Galactic bulge season about 120 million stars are regularly monitored and analyzed by the EWS system.", I don't think that should be a problem.
Burnt? (Score:2, Funny)
Re:Burnt? (Score:3, Informative)
Re:Burnt? (Score:1)
In other words, it is far from a perfect "lens". Sort of like astigmatism or a non-geometricly perfect lens?
Re:Burnt? (Score:2)
The planet is the lens, not the focus (Score:4, Interesting)
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.
I thought this experiment was done a long time ago (Score:3)
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.