A scientific team led by the Max Planck Institute Quantum Optics, with the participation of the Institute of Astrophysics of the Canary Islands (IAC), has confirmed the high level of precision of a new calibration system, called ‘laser frequency comb’, which can be key to the detection of planets such as Land.
The search for exoplanets it is getting closer and closer to the goal of finding a planet like Earth orbiting a star like the Sun in its habitability zone, that is, at the necessary distance, neither too close nor too far, so that liquid water can exist on its surface .
A planet in orbit produces a gravitational pull on its star that results in a small movement that astronomers can detect through slight changes in the star’s spectrum. This technique is known as the radial velocity method and allowed the discovery of the first orbiting exoplanet a sun-like star, whose authors have recently been awarded the 2019 Nobel Prize in Physics.
To measure these tiny variations in the spectrum of host stars, astronomers need spectrographs of the highest precision.
So, the IAC has participated in a new job, led by the Max Planck Institute for Quantum Optics and published in the journal ‘Nature Astronomy’, which supports a technology that can be key to discover planets like Earth.
Specifically, the team has tested a calibration system called ‘laser frequency comb’, a technique that received the Nobel Prize in Physics 2005, demonstrating unprecedented short-term accuracy.
“To date, it has been shown, on longer time scales, of the order of years, an accuracy of approximately 80 centimeters per second, using other means of calibration, but still insufficient for the discovery of an Earth twin, “says Jonay González Hernández, Ramón y Cajal researcher at IAC and co-author of the article.
As indicated, this study has demonstrated a short-term accuracy, of the order of hours, of one centimeter per second, “which opens up the possibility of finding habitable planets like the Earth orbiting stars like the Sun”. “But we still have to prove this long term accuracy“, Add.
Solar light observation
For its part, as explained Borja Toledo Padrón, PhD student Severo Ochoa-LaCaixa of the IAC and co-author of the research, one of the tests that have been carried out is the observation of sunlight reflected in Ceres, dwarf planet of the Solar System. “Despite many effects we know on this dwarf planet, we have been able to measure absolute speed with an accuracy of three meters per second; this demonstrates the accuracy of this calibration system,” he says.
To carry out this work, in which IAC researchers Rafael Rebolo and Alejandro Suárez Mascareño have also participated, it has been necessary to compare two Laser Frequency Comb (LFC) systems coupled to the instrument HARPS which operates in the 3.6 meter telescope of the European Southern Observatory (ESO) at the La Silla Observatory in Chile.
The campaign has confirmed the high stability and accuracy of the system CFL, which reveals its true potential for higher sensitivity astronomical spectroscopy and provides an ideal tool for the search for Earth-like exoplanets.