9/10/2023 0 Comments Center of a blackholeThe ELT’s MICADO instrument will push the effective stellar detection sensitivity by more than five magnitudes, making it possible to study the stars across the entire range of stellar masses, including those smaller than the Sun. When we look towards Sagittarius A*, we see so many objects that distinguishing individual stars close to the black hole is difficult, even with adaptive optics on today’s large telescopes. Monitoring the orbits of these stars, including with the GRAVITY instrument on ESO’s Very Large Telescope Interferometer, has become key to studying the properties of the black hole at the centre of the Milky Way. Surprisingly, as many as 40 cold giant stars (so-called S stars) were found to reside in the immediate vicinity of the black hole, whose gravity forces the stars to orbit very quickly the shortest period star confirmed so far orbits the black hole in just 12 years, and the brightest star in the system is on a 16-year orbit. With the advent of adaptive optics on very large telescopes, scientists could resolve the brightest stars around Sagittarius A*. Since investigations of the Galactic Centre were first carried out in the early 1990s, astronomers have constantly been on a quest for higher resolution and sharper observations. Supermassive black holes will be characterised out to large distances with the ELT, allowing us to trace the build-up of supermassive central objects in galaxies when the Universe was as young as a quarter of its present age. The centres of most galaxies harbour supermassive black holes weighing in at more than a million times the mass of the Sun. The ELT will be able to accurately measure the 3D velocities of stars in massive star clusters and dwarf galaxies, where these intermediate mass black holes are thought to reside, allowing astronomers to find out more about them.Īnother mystery astronomers will be able to tackle with the ELT is the role supermassive black holes play in the formation and evolution of galaxies and structures in the Universe. These black holes represent a link currently missing between stellar-mass black holes and supermassive black holes, and they could serve as seeds in the early Universe for the formation of the supermassive black holes that we see today. An open question awaiting the advent of the ELT is the existence and demographics of intermediate mass (100–10000 solar masses) black holes. The Galactic Centre also provides us with a place to study the accretion of matter onto supermassive black holes, as well as to better understand the relationship between their activity and star formation at the centre of galaxies.īlack hole research with the ELT will not be limited to the Galactic Centre. The ELT will enable astronomers to build on research done with ESO telescopes on the Galactic Centre, which was recognised with the 2020 Nobel Prize in Physics. A dense cluster of stars surrounds the supermassive black hole, and the ELT will enable astronomers to study the behaviour of these stars in their strange environment with a level of detail and quality that we could only dream of reaching with smaller telescopes. The centre of the Milky Way is a unique laboratory for exploring gravity around the closest supermassive black hole, a giant with four million times the mass of the Sun. For example, they can infer much about a black hole by tracking the movements of stars and gas around it, something the ELT will excel at. Since these objects are black - they don’t directly emit nor reflect light - astronomers rely mostly on indirect observations to spot their presence and study them. A supermassive black hole lies at the centre of almost every large galaxy, including the Milky Way, while some of the less massive black holes are thought to form when massive stars reach the end of their lives. Astronomers have evidence that black holes are extremely common throughout the Universe.
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