For the first time in its history, the Institute of Astronomy of the National Autonomous University of Mexico (UNAM) is participating, through a consortium of European institutes from France, Portugal, the United Kingdom, Belgium, Ireland and Germany, in the modernization of one of the most important telescopes for astronomy: the Very Large Telescope Interferometer (VLTI), located in Cerro Paranal, in northern Chile. The project is called GRAVITY+ AND It consists of an upgrade of the VLTI that transforms its performance and sky coverage. It seeks to incorporate lasers to create artificial stars and correct atmospheric distortion, and wants to create an improved system to more precisely measure the masses of black holes, according to Germany’s Max Planck Institute for Extraterrestrial Physics, which is leading this project.
The VTLI consists of the combination of the four units of the Very Large Telescope (VLT), eight-meter diameter telescopes, working simultaneously to observe the same object in the sky. “It’s as if we had synthesized a telescope of over 130 meters in diameter,” explains Joel Sánchez Bermúdez, doctor of Physics and Space Sciences at the Institute of Astronomy, one of the scientists involved in the project, for Gaceta UNAM, the university’s biweekly publication.
Salvador Cuevas Cardona, a physicist from the Instrumentation Department of the Institute of Astronomy, designed an optical element which he called Grisma—from English grateful (grid) e prism (prism) – and is key within one of the enhancement packages, as it will increase the spectral resolution four times more than it currently is, according to the Gazette. The piece created by Cuevas is made of germanium, a chemical element known for its use in semiconductors such as transistors, but much less exploited than the silicon used in computer and mobile phone chips, integrated circuits and memories, as he explains. “Depending on the number of lines per millimeter of the diffraction grating part and the diffraction index of the prism, the spectral resolution increases,” the publication reads. Furthermore, the Instrumentation Department of the Institute of Astronomy designs and builds the mechanical and electronic components of the filter wheel of the new high resolution (HR) spectrograph which will be installed in GRAVITY+ in 2027.
The Mexicans behind the project
For 38 years, Salvador Cuevas Cardona worked in the Astronomical Instrumentation department of the UNAM Institute of Astronomy. His work includes the design and production of instruments for national and international observatories, such as the verification instrument for the Gran Telescopio Canarias (GTC) in Spain, and the fusion of science and art, such as the lenses integrated into the Divinità in Luce stained glass window in the church of Santa Maria degli Angeli, Rome, in which perfect images of the sun are projected during the equinoxes and solstices, in the center of the rotunda in front of the temple entrance.
Joel Sánchez Bermúdez is an expert in the use of interferometric data, a technique that combines waves, such as light, radio, or sound, to make high-precision infrared measurements for studying stellar physics. The central axis of his research is the study of star formation and evolution using high angular resolution infrared techniques, according to his biography. In 2018, he was a member of the scientific team led by Nobel Prize winner Rehinard Genzel for discovering that the formation of black holes is a robust prediction of the general theory of relativity.
