Hubble captures strange shadow of possible exoplanet

Photo: NASA, ESA and J. Debes (STScl)
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Hubble telescope might have captured the shadow of a possible planet. The images offer scientists new ways in discovering existing planets.

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The presence of a previously unknown planet could have been disclosed in a unique way, by having its shadow photographed by the Hubble Telescope. The curious cast was observed on the gas dust disks that surround a young star in a far-away galaxy. According to scientists, the planet itself is not casting the shadow but its gravity is pulling on the material near the star, warping the inner part of the disc and this in return is casting the shadow across the surface of the inner disk.

According to a team of astronomers, led by John Debes form the Space Telescope Science Institute in Baltimore, Maryland, this is the most plausible scenario for explaining the strange shadow they have observed in the Hydra constellation, some 192 light-years away from Earth. The star they have been watching is 8 million years old and slightly less massive than our own sun. The phenomenon described was observed while analyzing 18 years’ worth of data taken by NASA’s Hubble Space Telescope.

“This is the very first disk where we have so many images over such a long period of time, therefore allowing us to see this interesting effect,” Debes said in a press statement. “That gives us hope that this shadow phenomenon may be fairly common in young stellar systems.”

Debes said that his first clue about the possible existence of an exoplanet was given by the fact that a brightness in the disk changed with position. This asymmetry was observed in 2005 but further observations were needed in order to make a definitive determination about its causes.

Searching the archive, Debes’ team put together six images from several different epochs. The observations were made by STIS and by Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS).  STIS is equipped with a coronagraph that blocks starlight to within about 1 billion miles from the star, allowing Hubble to look as close to the star as Saturn is to our sun. Over time, the structure appeared to move in counterclockwise fashion around the disk, until, in 2016, it was in the same position as it was in images taken in 2000.

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A new Jupiter-sized planet in Hydra constellation

Initially, astronomers believed that the feature was part of the disk but its rapid movement left them puzzled as gravity laws show that disks rotate at glacial speeds and the outermost parts of the disk should take centuries to complete one rotation.

“The fact that I saw the same motion over 10 billion miles from the star was pretty significant, and told me that I was seeing something that was imprinted on the outer disk rather than something that was happening directly in the disk itself,” Debes said in the same statement. “The best explanation is that the feature is a shadow moving across the surface of the disk.”

This is how scientists came to consider the existence of an exoplanet as the cause for the strange phenomenon. According to their calculations, the planet would have to be as large as Jupiter in order to have sufficient gravitational pull to create the shadow.

The research also offers new ways of discovering new planets by analyzing and studying the indirect evidence that proves their existence.

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