Free Astronomy Magazine May-June 2020

MAY-JUNE 2020 T his visible light wide-field view shows the rich star clouds in the constellation of Sagittarius (the Archer) in the direction of the centre of our Milky Way galaxy. The entire image is filled with vast numbers of stars — but far more remain hidden behind clouds of dust and are only revealed in in- frared images. This view was cre- ated from photographs in red and blue light and forming part of the Digitized Sky Survey 2. The field of view is approximately 3.5 degrees x 3.6 degrees. [ESO and Digitized Sky Survey 2. Acknowledgment: Davide De Martin and S. Guisard] the next orbit is rotated with re- gard to the previous one, creating a rosette shape. General Relativity provides a precise prediction of how much its orbit changes and the latest measurements from this re- search exactly match the theory. This effect, known as Schwarzschild precession, had never before been measured for a star around a super- massive black hole. The study with ESO’s VLT also helps scientists learn more about the vicinity of the supermassive black hole at the centre of our galaxy. “Because the S2 measurements fol- low General Relativity so well, we can set stringent limits on how much invisible material, such as distrib- uted dark matter or possible smaller black holes, is present around Sagit- tarius A*. This is of great interest for understanding the formation and evolution of supermassive black holes,” say Guy Perrin and Karine Perraut, the French lead scientists of the project.