New Planet Discovered With The Help Of Its Shadow

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Shadows play a major role in space discoveries. Around 1,000 planets around other stars got cataloged by the shadow they had cast on their parent star. Recently, Hubble has pointed scientists to the possibility of the new planet of a young star called TW Hydrae. This unseen planet is causing a huge shadow to sweep across the disk of gas and dust encircling the young star - like hands of a clock (but in an anti-clockwise direction). The shadow takes 16 years to make one complete rotation across the disk.

According to a news release at the Hubble site, Hubble has been observing the star for last 18 years. Astronomers have a birdeye's view of the disk which is tilted face-on to Earth and have assembled a time-lapse movie of the rotation of its shadow.

Some astronomers think that the gravitational force of this planet in the disk is pulling on material near the star and is warping the inner part of the disk. They theorize that this twisted, misaligned inner disk is the one casting the shadow on the outer disk.

TW Hydrae is 192 light-years away and is about 8 million years old. It is situated in the constellation 'Hydra' and is slightly less massive than our Sun.

According to Science Daily, when the astronomers studied the images of the star taken by the NASA's Hubble Space Telescope one year apart, they found a shadow moving in the anti-clockwise direction. Using archival data, they found that the shadow completes a rotation around the central star in every 16 years. They know that the dim area has to be the shadow because the dust and the gas in the disk move at a much slower speed.

John Debes, who led the team of astronomers at the Space Telescope Science Institute in Baltimore, Maryland, present his results at the winter meeting of the American Astronomical Society in Grapevine, Texas on January 7, 2017.