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The Daily Wildcat

The Daily Wildcat


    Starlight blocking device could reveal new planets

    Looking for Earth-like planets in distant solar systems may be a little easier thanks to a UA scientist’s new optics innovation.

    Grover Swartzlander, an associate professor in optical sciences, has developed a device that cancels out starlight so scientists can view distant planets.

    The main problem facing astronomers who study planets beyond our solar system is they are nearly impossible to see because the brightness of the star overwhelms that of the planet, said astronomy professor Nick Woolf.

    The device solves this problem by twisting the light traveling through a telescope in such a way that it cancels out, leaving the planet’s illumination, Swartzlander said.

    This could allow astronomers to study the reflected light from the planet for traces of oxygen-rich atmospheres.

    The key to this device is an optical vortex mask, a thin plastic or glass structure similar to a spiral staircase that will slow certain color wavelengths, thereby canceling out the light.

    “”If you shine a laser beam through a vortex, it will send a black dot through the middle of the beam,”” said Masud Mansuripur, an optics professor. “”If you take a cross-section, it will look like a donut.””

    The mask will create a vortex, effectively changing the phase of the light around the edge of the donut, Mansuripur said.

    In astronomical applications, the proper vortex mask would separate the light from the star and the light from the planet, Mansuripur said.

    “”The main breakthrough here is studying it in the configuration to block light,”” Swartzlander said.

    Blocking starlight is essential to studying planets because the light from the star is 10 billion times stronger than the light reflected off the planet.

    “”There has been a push for many years to get rid of starlight without getting rid of light from the planet,”” Swartzlander said.

    A similar situation can be seen with the naked eye.

    Just before the sun rises, the planet Venus is bright, but after sunrise, the planet disappears from view because the sun is over a billion times brighter, Woolf said.

    Once the light reflected by the planet is isolated, astronomers can use a filter to study the light spectrum for signs of an atmosphere with oxygen, Mansuripur said.

    The development of a light-canceling device would mark a new way planets could be discovered.

    Approximately 170 planets outside of the solar system have been discovered, almost all of which were detected by measuring the star’s gravitational wobble caused by the presence of a planet, Woolf said.

    Only three or four of these planets were discovered through other methods, such as measuring the star’s change in brightness due to a planet passing in front of it, Woolf said.

    These ways only allow astronomers to detect the presence of planets but not the light spectrum, Woolf said.

    While there are no immediate plans for the device’s application, Swartzlander said it could be put into telescopes within a few months, but they would not be very useful due to disturbances from the atmosphere.

    A better application for the device could be used in an orbiting telescope that could possibly separate the light from the planet without being affected by the atmosphere, Swartzlander said.

    This development will have to wait because the Terrestrial Planet Finder project was cut from NASA’s 2006 budget, Woolf said.

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