An international team of scientists have discovered a population of rogue exoplanets that appear not to be orbiting a host star. Published in Nature, the study used a technique known as gravitational microlensing to identify ten planets that cannot be attributed to a host star.
The technique, which has been used to find several other exoplanets, involves utilising a phenomena first predicted by Albert Einstein. He realised that massive objects, like planets or stars, bend the fabric of spacetime, which distorts passing light rays. If a planet moves in front of the light of a distant star, the mass of the planet bends the light from our perspective, distorting and magnifying it, offering a glimpse of the planet responsible.
The planets are all Jupiter-sized (which is eleven times the diameter of Earth), and from further analysis, it has been confirmed that all of them are at least ten astronomical units (AUs) from a star. One AU is the equal to the distance from the Earth to the Sun.
Although, this technique has only revealed very few exoplanets due to the rarity of a planet passing in front of another star, the ten that have been found in this study suggest that these objects could be extremely common.
It is likely that these planets will have formed as our own solar system did – from an orbiting dust cloud around the Sun, gravitating together to form larger and larger clumps of rock, until eventually a planet is created. It is possible that these newly formed planets were then scattered by something large enough to affect the gravitational pull around the host star.
Image courtesy of: Devon1980
Sumi, T., Kamiya, K., Bennett, D., Bond, I., Abe, F., Botzler, C., Fukui, A., Furusawa, K., Hearnshaw, J., Itow, Y., Kilmartin, P., Korpela, A., Lin, W., Ling, C., Masuda, K., Matsubara, Y., Miyake, N., Motomura, M., Muraki, Y., Nagaya, M., Nakamura, S., Ohnishi, K., Okumura, T., Perrott, Y., Rattenbury, N., Saito, T., Sako, T., Sullivan, D., Sweatman, W., Tristram, P., Yock, P., Udalski, A., Szymański, M., Kubiak, M., Pietrzyński, G., Poleski, R., Soszyński, I., Wyrzykowski, �., & Ulaczyk, K. (2011). Unbound or distant planetary mass population detected by gravitational microlensing Nature, 473 (7347), 349-352 DOI: 10.1038/nature10092
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