Polish way to the planets that broke away from the stars
Scientists have long suspected that there are Earth-like planets in the Universe, but which are not gravitationally bound to any star. Now astronomers from the University of Warsaw have found traces of such objects for the first time.
Not all planetary systems are as stable as the Solar System. Planets in young systems can collide with each other or fall on a star. But they can also – and this happens quite often – break away from the parent system. This is one wayoin which free planets are formed.
The problem is how to observe such planets – after all, except for very young objectsow, free planets cannot be observed directly – they do not emit light. To search for them, astronomers use the gravitational lensing method. They describe their discovery in the latest issue of the prestigious weekly magazine Nature.
– Microlensing is a unique method of finding characteristic brightenings of stars – mowi in an interview with PAP prof. Andrzej Udalski of the Warsaw University Astronomical Observatory. He is the manager of the OGLE project, under which theorego research was done.
The first author of the publication, Przemek Mroz, a doctoral student at OA UW adds: When between an observer on Earth and a distant star (. ) passes a free planet, its gravity is able to bend the light of the star and we observe krotic brightness enhancement.
The duration of the microlensing phenomenon depends on the mass of the lens – The smaller the mass, the krotth phenomenon. While typical microlensing brightenings caused by stars last from a few to several hundred days, phenomena caused by Jupiter-mass planets typically last 1–2 days, and by terrestrial planets – just a few hours.
Polish researchers in the OGLE project have verified how many free planets there are with the mass of Jupiter. For every hundred stars, there are less than 25 free Jupiterow. Meanwhile, an earlier study – by the Japanese-New Zealand MOA team – predicted that there would be 8 times as many such bodies.
– The second very important result of our work is the discovery (. ) microlensing phenomena, whichore last only a few hours each. Such phenomena should be caused by Earth-mass planets,” describes Przemek Mroz. As reported, with estimatesoin the OGLE team shows that there should be between one and five Earth-like free planets per star.
New observations of microlensing phenomena were carried out as part of the OGLE project in 2010–15. Used a telescope with a diameter of 1.3 m, located at the Las Campanas Observatory in Chile – a place with the world’s best conditions for astronomical observations.
– We analyzed the glare curves of nearly 50 millionow stars observed for six years. In total, it is almost 400 billionoin single measurementoin clarity – mowi Przemek Mroz.
Thanks to the installation of new detectorsoin the light in 2010 have significantly increased the observational capabilities of the Polish telescope: a large area of the sky mohead to be photographed every 20 minutes. Such frequent observations make it possible to detect krotkotrival microlensing phenomena caused by free planets – terrestrial and jupiter.
– However, we cannot exclude the possibility that some of these ultracrotion of such phenomena is caused by unknown flare stars or other astrophysical sourcesodła – notes Dr. Jan Skowron, coołautor of publications in the "Nature".
The discovery would not have been possible without years of observations by the OGLE sky survey. OGLE project, whichory is one of the largest wspoHE MODERN REVIEWoin the sky, this year celebrates 25. anniversary. One of the first targetsoin scientific OGLE review was the discovery and study of gravitational microlensing phenomena. Current research involves a wide range of areas wspomodern astrophysics – search for extrasolar planets, study of the structure and evolution of the Milky Way and neighboring galaxies, variable stars, quasarsoin, transient phenomena (new stars, supernovae).