Last week, four lasers were aimed at the European Southern Observatory (ESO) on Mount Paranal in Chile, creating a so-called “artificial star.” According to THATit will allow astronomers to measure and correct blurriness caused by atmospheric turbulence.

This launch marks a major milestone for the GRAVITY+ project, a major upgrade of ESO’s Very Large Telescope Interferometer (VLTI).The upgrades give VLTI the ability to study dim and distant objects previously unobservable and cover much of the southern sky.

First observations

GRAVITY+ and ESO teams aimed new lasers at a cluster of massive stars in the Tarantula Nebula in the Large Magellanic Cloud. The first results show that what was thought to be a single extremely massive star is actually made up of two closely spaced stars.

“This demonstrates the potential of the updated instrument to precisely probe the structure and dynamics of stellar systems,” said Dr. Rebeca Garcia Lopez from the University of California.

She added thatThe new system offers a unique opportunity to study in detail the formation of solar systems similar to ours with unprecedented precision.

The principle of operation of an artificial star

The system combines light from several eight-meter telescopes through interferometry.Lasers create a bright point at an altitude of about 90 km,which is used to correct atmospheric distortions using adaptive optics. Previously, one had to rely on bright guide stars near the object, which limited the number of observations available. Now VLTI can correct the image anywhere in the sky.

Dr. Taro Shimizu from the Max Planck Institute for Extraterrestrial Physics emphasized that the updated instrumentopens access to objects of the early Universe,existing just a few hundred million years after the Big Bang.

GRAVITY and GRAVITY+ achievements

GRAVITY has already made it possible to image exoplanets, observe the rotation of stars around the Milky Way’s supermassive black hole, and measure gravitational redshift. For this, Professor Reinhard Genzel and Professor Andrea Ghezreceived the Nobel Prize in Physics in 2020.

The instrument also provided the first observational evidence of magnetospheric accretion, the process by which material is deposited onto newborn stars. The results were published in Nature in 2020, with Dr. Garcia Lopez as lead author.

GRAVITY+ upgrades telescopes and underground tunnels where light beams are summed. Deformable mirrors, modern sensors and advanced adaptive optics have been introduced. Lasers create reference points, allowing atmospheric distortions to be corrected without reference to real stars, opening up the entire southern sky for exploration.

UCD, led by Dr. García López, is involved in upgrading the spectrograph, increasing spectral resolution. In collaboration with the National Autonomous University of Mexico (UNAM), they developedholographic grating prism and test and install it in VLTI.

Significance for science

GRAVITY+ significantly expands the capabilities of astronomy, allowing you to observe objects previously hidden due to atmospheric blur. The use of lasers and advanced interferometry makes it possible to study the evolution of galaxies, star formation processes and the formation of planetary disks with unprecedented precision,as well as measure the mass of supermassive black holes and study active galaxies at vast distances.