Astronomers from the Astronomical Observatory of the University of Warsaw used the phenomenon of microgravity, thanks to which they determined the mass of the invisible object with high accuracy.
Astronomers in Warsaw noticed the unusual brightness of a particular star in the daily portion of data monitored by the European space mission Gaia on April 18, 2019. – We decided to look closely at this phenomenon, called Gaia19bld, in the hope of a very strong signal amplification in the coming days. Krzysztof Rebicki, a doctoral student at the Astronomical Observatory of the University of Warsaw (OA UW), is the lead author of the analysis and one of the publications on the Gaia19bld phenomenon.
The astronomers speculated that it would be possible to record changes in the image structure of the light source (the star) in the microlensing phenomenon, which – although well defined in theory – had not been directly observed before. They predicted the extent and width of the maximum eclipse, after which, in consultation with other astronomers (for example from the Sorbonne in Paris and the University of Heidelberg), observations were planned on the largest telescopes in the world.
– For the first time, we were able to record not only two separate images of the source, but also change their position during the lens phenomenon. This effect is directly caused by Albert Einstein’s general theory of relativity, and was predicted by Professor Bohdan Baczinski, a prominent Polish astronomer and a graduate of the University of Warsaw, more than 30 years ago.
Gravitational microlensing is a phenomenon when another invisible object is found in our line of sight from Earth to the observed star. This then causes the star to temporarily brighten in a distinct way.
Thanks to the collected observational data, it was possible to determine the mass of the dark object that served as a gravitational lens. The object has a mass slightly greater than the Sun. If it’s an ordinary star, within a few years, telescopes should be able to see it when the source detaches from the lens in the sky. An alternative possibility is a neutron star or black hole, but the lens appears to be too lightweight to believe in such a scenario.
The source star’s brightness has been observed for about a year by various instruments, both space telescopes (such as the European Space Agency’s Gaia or NASA’s Spitzer) and ground-based telescopes, from small robotic telescopes (including those operated by astronomy enthusiasts), to large telescopes It is eight meters long and belongs to the European Southern Observatory (ESO). Of course, the data was also collected by the OGLE project telescope, operating in Chile.
– This is an excellent example of cooperation between various space agencies, but also between scientists and astronomy enthusiasts. Increasingly, important astronomical discoveries are the result of the work of many research groups using instruments located in different places. This ensures that phenomena can be observed without interruption, because in one of the observatories there are always suitable observing conditions – commented Łukasz Wyrzykowski from the Research Center of the University of Warsaw.
The results of the research were presented in three scientific articles in “Natural Astronomy” and “Astronomy and Astrophysics”.
For many years, Polish scientists have been specialized in observing and analyzing microgravity phenomena (eg as part of the OGLE project). The Astronomical Observatory of the University of Warsaw (OA UW) also has a group responsible for organizing a network of ground-based telescopes that study the phenomena detected by the Gaia satellite. It is chaired by Professor Łukasz Wyrzykowski.
Main image source: K. Rybicki, Ł.Wyrzykowski, A. Cassan, E.Bashet
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