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Looking Directly at Extrasolar Planets

Posted by ScuttleMonkey on Mon Dec 05, 2005 04:24 PM
from the flushing-out-the-noise dept.
Space Technology
D2Deek writes "Science Daily is reporting on a new device called an Optical Vortex Coronagraph that's been invented to directly image planets orbiting other stars by using a special lens that "spins out" the light from the star leaving only the reflected light from the planet." I just can't imagine trying to clean a lens shaped like a giant corkscrew.
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  • Seeing the planet next to its bright star has been compared to trying to discern, from a hundred meters away, the light of a match held up next to the glare of an automobile's headlight.

    I thought a planet must be illuminated by light from a star, and not emitting light itself?

    Anyway, this technology might be useful for photography, so that one will never get an overexposed shot again.

    • I thought a planet must be illuminated by light from a star, and not emitting light itself?


      What this is referring to is the light directly from the star outshining the planet's reflected light.

      I would assume, at anyrate. I am still trying to load the article.

        • Re:The light of a planet (Score:4, Informative)

          by Skye16 (685048) on Monday December 05 2005, @04:53PM (#14188669)
          Your point is valid. A better analogy would be more like a mirror the size of an eraser, reflecting light from a match held a few hundred meters away, in front of a car headlight.

          (Actually, I don't know if the proportions are even remotely close, but meh.)

        • Re:The light of a planet (Score:4, Insightful)

          by Bradee-oh! (459922) on Monday December 05 2005, @04:54PM (#14188678)
          I tend to think it's quite appropriate. Granted, in the strictist of senses, yes a planet reflect the star's light while a match creates its own. But from a analogical sense, it works. The brightness of the light from the match is a fraction of the light coming out of the headlight, just as the light reflected towards us from the planet is many times dimmer than the starlight itself. When applied to very large planets, which are the only extra-solar ones we've discovered so far, the size comparison works as well. Plus who's to say the planet is not a dim-light emitting gas giant? ;)
           
          The point is, the analogy does get across the difficulty of this acheivement quite well, even moreso when you don't knitpick it to oblivion.
    • They already have this technology - so another reason not to sunbath naked on your roof.

    • Uh... from the article summary:

      "...using a special lens that "spins out" the light from the star leaving only the reflected light from the planet."

    • Re:The light of a planet (Score:4, Informative)

      by MindStalker (22827) <jlarsen AT fsu DOT edu> on Monday December 05 2005, @04:30PM (#14188445) Journal
      This is actually more about the angle of light, say I want to capture all light in a very tight .005% angle. Unfortunatly there is a sun at the very very edge of my shot. Even though its technically out of the angle of my shot with conventional lenses the sun will glare through. This technology allows light at the edges of the lense to be spun off. It really has nothing to do with intensity.
      • Note: there should be a lot more Zeros in that % I guess. I don't know astronimically speaking if your trying to view a planet from hundred light years away, and don't want to see its sun, you would be talking about an angle of 1E-100 something I assume. Anyone know?
        • The closest extrasolar planet is (according to this [obs-hp.fr]) Gliese 876. It's situatet 15 lightyears from us which works out to 15years*300000km/s*86400s*364.25days=472068000km. The planetary radius is 0.1 times the solar radius (our sun). Which gives a diameter of (according to wikipedia [wikipedia.org]) 1392000km*0.1=139200km. Thus (according to Python) the angle is; atan(139200km/472068000km)~2.9*10^-4 radians, which is ~0.017 degrees. A supprisingly big number in my opinion.

          • Re:The light of a planet (Score:3, Informative)

            by Anonymous Coward
            Your math is off.

            15years*300000km/s*86400s*364.25days = 14162040000000km, not 472068000km

            Thus, the angle comes to 5.63e-7 degrees, or 0.002 arcseconds


          • The closest extrasolar planet is (according to this) Gliese 876. It's situatet 15 lightyears from us which works out to 15years*300000km/s*86400s*364.25days=472068000km. The planetary radius is 0.1 times the solar radius (our sun). Which gives a diameter of (according to wikipedia) 1392000km*0.1=139200km. Thus (according to Python) the angle is; atan(139200km/472068000km)~2.9*10^-4 radians, which is ~0.017 degrees. A supprisingly big number in my opinion.

            I think you dropped a 300,000 km/s.

            15 years

            • "I think you dropped a 300,000 km/s."

              Hadn't you heard? The Galactic Senate, in an effort to save our endangered antimatter reserves, lowered the speed of light to 1 km/s in order to conserve energy. Phhzzggzztyt Abbmmmun, the senior senator from Hierantos VIII, said "Someone needs to think of the larvae."

              Of course, it wasn't unanimous. L'fhong Di Tabax, representing the Chorabax Cluster suggested that it was "The Andromeda energy cartel's fault" and added that "if they don't shape up, we should bom

          • Re:The light of a planet (Score:2, Informative)

            by Anonymous Coward
            Not to nitpick - but according to Celestia (take it with a grain of salt, of course) Epsilon Eridani (Gliese 144) is closer than Gliese 876 (10.5 ly as opposed to 15.3 ly) and it has at least 2 known planetary satellites. See here: http://www.daviddarling.info/encyclopedia/E/EpsEri .html [daviddarling.info] or google for "Epsilon Eri."

            On a side note, Eps Eri C (the smaller planet) seems to orbit about 28 au from its parent star - I would think this would be a perfect candidate for this technology! (I'm too lazy to work out t

          • Re:The light of a planet (Score:5, Informative)

            by jgoemat (565882) on Monday December 05 2005, @06:07PM (#14189353)
            The 472,068,000 doesn't include the 300,000km/s. The real number would be 142,009,200,000,000. (also a year is 365.25 days, but the 15 light-year measurement is much less accurate than that I suspect) The page you point to says the planet's average orbit is 0.2 times the earth-sun distance, about 31.5 million km. That gives an angular distance between the star and planet of about 0.0000127 degrees, or 0.045 arcseconds. The hubble can resolve about 0.07 arcseconds, if we can separate the glare from the star bleeding over, then we are close.
    • I thought a planet must be illuminated by light from a star, and not emitting light itself?

      It can reflect light from stars.

  • Do not... (Score:5, Funny)

    by OakDragon (885217) on Monday December 05 2005, @04:27PM (#14188401) Journal
    Do not look directly at extrasolar planets with remaining good eye.

  • Optical Vortex Coronagraph (Score:5, Funny)

    by ch-chuck (9622) on Monday December 05 2005, @04:34PM (#14188486) Homepage
    Is that anything like the Total Perspective Vortex [wikipedia.org] ??
  • I just can't imagine trying to clean a lens shaped like a giant corkscrew.
    Just put some isopropyl alcohol on a giant corkscrew-shaped q-tip. What's the big deal?
    • http://www.imdb.com/title/tt0089886/ [imdb.com]

      Kent: My condolences on your meltdown.
      Chris Knight: What meltdown, Kent?
      Kent: I'm not saying you had one, because how would I know? But just in case you do.
      Chris Knight: You slime!
      Kent: It's your own fault, Knight. Didn't anyone tell you to make sure your optics are clean?

  • Actual Press Release text (Score:4, Informative)

    by Anonymous Coward on Monday December 05 2005, @04:38PM (#14188527)
    ... seeing that the server is slashdotted ...

    A new optical device might allow astronomers to view extrasolar planets directly without the annoying glare of the parent star. It would do this by "nulling" out the light of the parent star by exploiting its wave nature, leaving the reflected light from the nearby planet to be observed in space-based detectors.

    About ten years ago, the presence of planets around stars other than our sun was first deduced by the very tiny wobble in the star's spectrum of light imposed by the mutual tug between the star and its satellite. Since then, more than 100 extrasolar planets have been detected in this way. Also, in a few cases the slight diminution in the star's radiation caused by the transit of the planet across in front of the star has been observed. Many astronomers would, however, like to view the planet directly, a difficult thing to do.

    Seeing the planet next to its bright star has been compared to trying to discern, from a hundred meters away, the light of a match held up next to the glare of an automobile's headlight. The approach taken by Grover Swartzlander and his colleagues at the University of Arizona is to eliminate the star's light by sending it through a special helical-shaped mask, a sort of lens whose geometry resembles that of a spiral staircase turned on its side.

    The process works in the following way: light passing through the thicker and central part of the mask is slowed down. Because of the graduated shape of the glass, an "optical vortex" is created: the light coming along the axis of the mask is, in effect, spun out of the image. It is nulled, as if an opaque mask had been placed across the image of the star, but leaving the light from the nearby planet unaffected.

    The idea of an optical vortex has been around for many years, but it has never been applied to astronomy before. In lab trials of the optical vortex mask, light from mock stars has been reduced by factors of 100 to 1000, while light from a nearby "planet" was unaffected (see figure).

    Attaching their device to a telescope on Mt. Lemon outside Tucson, Arizona, the researchers took pictures of Saturn and its nearby rings to demonstrate the ease of integrating the mask into telescopic imaging system. This is, according to Swartzlander (520-626-3723, grovers@optics.arizona.edu), a more practical technique than merely attempting to cover the star's image, as is done in coronagraphs, devices for observing our sun's corona by masking out the disk of the sun. It could fully come into its own on a project like the Terrestrial Planet Finder, or TPF, a proposed orbiting telescope to be developed over the coming decade and designed to image exoplanets.

    Foo et al., Optics Letters, 15 December 2005 Summary of articles related to optical vortex on Swartzlander's Web page

    Someone more patient than I can put in the links to the figures. See http://aip.org/pnu/2005/755.html [aip.org] for everything.

  • cleaning (Score:5, Funny)

    by winkydink (650484) * <sv.dude@gmail.com> on Monday December 05 2005, @04:38PM (#14188534) Homepage Journal
    I just can't imagine trying to clean a lens shaped like a giant corkscrew.

    Just run a lint-free Debian logo through it a couple of times.

  • Strip coating (Score:5, Interesting)

    by asadodetira (664509) on Monday December 05 2005, @04:40PM (#14188553) Homepage
    The submitter mentioned cleaning lenses and other optical equipment. I want to comment that that's a very tricky thing. Most optical manuals just say: Do not attempt to clean!! Some recent developments are in the area of strip coatings (you pour a polymer over the surface and peel it off to remove dirt without damaging the optics). This has been tried since the early XX century but only recently has became practical. Here's a link to a group that developed a sucessful formula for that process: http://www.uwplatt.edu/~hamiltoj/ [uwplatt.edu]
  • I wonder if it could be used to replace coronography, as for example letting you see only the solar emissions (winds and all that) without the disc of the sun, and this with no occultation, or even helping view the deviation of light nearby a star (in case this can be of any use) without having the annoying light of the star in between.

    I wonder if it could be applied to observing galaxies too... I mean, I'd be curious to know what other uses could be found to this technique

    • Re:Replacing coronography (Score:4, Informative)

      by Anonymous Coward on Monday December 05 2005, @05:06PM (#14188793)
      Apparently all the work so far is only computer simulations. There are some serious problems to overcome before this could be a practical system. The author states:

      "These calculations assume no aberrations or other scattering sources, and they assume the vortex mask can be made achromatic."

      http://www.u.arizona.edu/~grovers/ovc.html [arizona.edu]

      In other words, the lens material is made from unobtanium and the rest of the system has to be perfect. The author certainly knows this will never happen.

      Mike
  • A corkscrew shaped lens, eh? It's amazing the topographical capacity in lens engineering. I bet this is all fused silica. When will we have single crystal sciu light sources? I'm in no hurry. I study the magnetic recombinance of solar coronas. No need here for that source type. Let me jump back to times when I could just play games and not worry about lens and abberration and physics. GRRRR! Real life sucks.

  • That's... (Score:4, Funny)

    by Dirtside (91468) on Monday December 05 2005, @04:45PM (#14188598) Journal
    I just can't imagine trying to clean a lens shaped like a giant corkscrew.
    That's probably why you edit stories for Slashdot, instead of being, you know... a rocket scientist.

  • Foo et al. (Score:5, Funny)

    by dpbsmith (263124) on Monday December 05 2005, @04:49PM (#14188630) Homepage
    It's worth RTFA just to see a reference to "Foo et al."

    (The full paper title is "Optical Vortex Coronagraph" by Gregory Foo, David M. Palacios, Grover A. Swartzlander Jr., College of Optical Sciences, University of Arizona).

  • Azathoth have mercy (Score:4, Funny)

    by rolypolyman (933130) on Monday December 05 2005, @05:01PM (#14188753)

                "As Gilman looked into the Optical Vortex Coronagraph at the extrasolar planet, he became conscious of some formless alien presence watching him with horrible intentness. He felt entangled with something -- something which was not in the telescope, but which had looked through it at him. Something which would ceaselessly follow him.
                "Cautious investigators will hesitate to challenge the common belief that Gilman was killed by lightning, or by some profound nervous shock derived from an electrical discharge. Archaeologists and astronomers, however, are still trying to explain the bizarre designs impressed on the special helical-shaped mask, whose inner side bore ominous stains."

    • No no no... Lovecraft uses lots of adjectives and tells his stories from the first person. "As I looked through the aeons into the Optical Vortex Coronagraph at the extrasolar dark orb, I became conscious of some obscene nameless presence watching with horrible intentness."

  • The point (Score:5, Insightful)

    by oni (41625) on Monday December 05 2005, @05:29PM (#14189029) Homepage
    You wont be able to see any surface details, but the point, for those who don't already know, is that if you can look at just the light that's reflected, then you can run that light through a spectroscope. If you see in the spectroscope that there is free oxygen in the atmosphere, then you've probably found life. See, free oxygen (O2) doesn't occur anywhere in nature - except where it's created by life. So, if you find lots of O2 in the atmosphere, you've found a living planet (and a reason to build daedelus [geocities.com])
    • See, free oxygen (O2) doesn't occur anywhere in nature - except where it's created by life.

      And you know this because you have witnessed the entirety of nature? Or this has been deduced and isn't actually a fact, but an assumption?

      Actually, O2 does appear in places other than our planet (places assumed to be devoid of life), just not in abundance. But even an abundance is only a hint that life exists. There are inorganic processes that can create oxygen. These usually don't create abundant amounts, but we'v
      • Not that this is at all likely...

        Indeed. The real catch is, oxygen tends to get consumed by other common geological and chemical processes. If all life on Earth died today, oxygen would become a trace element in the Earth's atmosphere within a few thousand years (i.e. practically instantaneously on a geological timescale). Whatever process was generating atmospheric O2 would have to be doing it currently and continuously and on a massive scale. Although alternatives are not impossible, so far, there is

  • Frankly, I'm more interested in a comprehensive set of photos of our own solar system's planets, such as Pluto and the various "Planet X" candidates that pop on and off the public debate radar from over the years. At least we have the technology to actually visit these places today were we so inclined.

    I'm not saying it's unimportant to continue with research like this, only that I wish more effort were put into slightly less glamorous subjects like Pluto that could actually do us some tangible good one da
    • Worry not, for New Horizons, set to launch in January, will reach Pluto in Summer 2015 (it's one of the fastest spacecraft we've ever designed, and will get a gravitational slingshot boost from Jupiter.) Among other things, the New Horizons spacecraft will take the first clear pictures of Pluto.
  • This is extremely cool. I was wondering if there would be any way to do this in software (at least that technical explanation page shows there is a simulator) but thoguht that if it is based on slowing down light of a certain color, you would have to have all the phase info stored. Or at least extremely high resolution/range to have any data left after subtracting the green. I could be way off here but does anyone know of a way this technique could be used on an amateur telescope computationally based on light captured by a ccd without actually physically building a vortex lens? Is it true that this is based on a single color? Also, if you worked on the spectra of the star would this not also include spectra of the planet, i.e. is this really based on a pure black body incandescense i.e. pure green for this star and not really the full spectra of the star? Thanks.
  • For information, the European Space agency has a project named Darwin that intends to cancel the light of a star by destructive interferometry, leaving the neigboring planet alone: from its specifications, I retain that in order to "see" the planet, you must damp the star from a factor 10^9 in visible light (10^6 in IR). Basically this is how the Earth looks like close to the sun: 10^9 times less brilliant.

    Compared to this, the damping factor announced in the original paper (between 100 and 1000), would loo
  • Sounds like some researchers taking marketing lessons. They kinda missed the concept of 'the spin' though, took it literally, in thier quest to market themselves hunting for more welfare^H^H^H^H^H^H grant cheques.

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