Researchers from the Physics Department of the University of Salento, associated to the Istituto Nazionale di Fisica Nucleare (INFN, Italy's National Institute of Nuclear Physics) located in Lecce, have calculated the possible presence of a planet orbiting around a star in the Andromeda Galaxy. This could be the first time that a planet has been detected outside of our galaxy, the Milky Way, where more than three hundred planets orbiting around stars have been documented.
The discovery was made by Francesco De Paolis and Gabriele Ingrosso (INFN of Lecce), together with Sebastiano Calchi Novati (INFN of Naples) and researchers from Switzerland, Spain, and Russia. The results will be published in the prestigious British journal Monthly Notices of the Royal Astronomical Society.
The research is based on what is known as a “gravitational micro-lens”. According to this phenomenon, which was foreseen by Einstein, the gravitational field of a star deflects light from the part of the Universe that is on the other side of the star with respect to the side that the telescope is on. The light splits and then recombines, forming a highly magnified image of that part of the Universe.
The INFN researchers have developed a computer model that, based on the variations in luminosity created by this phenomenon, can detect a planet in orbit around the star that is acting as a lens (or "lens-star").
The INFN model was applied to observations performed in 2004 using the INT telescope in the Canary Islands, and the results suggest that there is a planet orbiting around a lens-star which, according to Francesco De Paolis, “is very likely to be located in the Andromeda Galaxy.... the planet could have a mass that is six to seven times greater than that of Jupiter, so it's quite large”. The great majority of planets that have been observed in the Milky Way, which to date are the only planets known to exist, have masses that exceed that of Jupiter.
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