Free Astronomy Magazine January-February 2019

13 JANUARY-FEBRUARY 2019 SPACE CHRONICLES E SO’s GRAVITY instrument on the Very Large Telescope (VLT) Interferometer has been used by scientists from a consortium of European institutions, including ESO, to observe flares of infrared ra- diation coming from the accretion disc around Sagittarius A*, the mas- sive object at the heart of the Milky Way. The observed flares provide long-awaited confirmation that the object in the centre of our galaxy is, as has long been assumed, a super- massive black hole. The flares origi- nate from material orbiting very close to the black hole’s event hori- zon — making these the most de- tailed observations yet of material orbiting this close to a black hole. While some matter in the accretion disc — the belt of gas orbiting Sagit- tarius A* at relativistic speeds — can orbit the black hole safely, anything that gets too close is doomed to be pulled beyond the event horizon. The closest point to a black hole that material can orbit without being ir- resistibly drawn inwards by the im- ns of o a T his visible light wide-field view shows the rich star clouds in the constella- tion 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 infrared images. This view was created 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 (www.eso.org/~sguisard )]