Astronomy: Precise mass of a lonely exoplanet determined for the first time
Although we already know dozens of exoplanets without their own star, their masses could only be estimated. Now a precise measurement has been achieved.
Artistic representation of the measurement of the lonely exoplanet
(Image: Yu Jingchuan, Peking University)
An international research group has succeeded for the first time in precisely determining the mass and distance of a lonely exoplanet, thus unequivocally proving for the first time that the celestial body is not a star. This has now been announced by Peking University, where research lead Dong Subo works. This was made possible by a microlensing event observed by observatories on Earth's surface and by space telescopes. According to the data collected, the celestial body, approximately 9800 light-years away, has a mass roughly equivalent to that of Saturn. The research group assumes that it originated in a star system and was later ejected from it.
Ideal Circumstances for Measurement
In astronomy, microlensing is a special case of so-called gravitational lensing, where a massive foreground object bends the light rays of objects behind it so strongly that they can be seen multiple times in front of it. However, unlike large gravitational lenses, microlenses do not produce separable images. Only a brightening of the object behind it can be detected. Nevertheless, this brightening reveals details about the foreground object, especially when these microlenses are observed from different locations. Through so-called parallax measurement, the fundamental values for the mass and distance of this foreground object can then be determined.
Videos by heise
Lonely exoplanets have been found since the beginning of the millennium, but much about them remains unknown. In the case of the celestial body now measured, researchers assume that the object originated in a protoplanetary disk and is not alone in interstellar space. Dynamic processes must then have ejected it from its "birthplace," after which it now drifts lonely through the Milky Way. The celestial body has exactly 0.219 Jupiter masses. The team sees the simultaneous observation of such microlensing events as promising for the analysis of other lonely planets as well. The discovery is presented in a research paper in the scientific journal Science.
(mho)
