Astrometry of Exoplanets Using Optical Interferometry: Insights from the GRAVITY Instrument

In March 2019, the GRAVITY collaboration unveiled the first spectrum and astrometry of an exoplanet achieved through optical interferometry. Four years on, we reflect on how this technique has changed our view of imaged exoplanets, offering enhanced astrometry (typically by several tens of milliarcseconds) and superior spectra compared to those obtained with single telescopes. But to what extent has this transformation occurred? What levels of precision can we now achieve, and what are the implications? In this talk, I will detail the method that facilitated these high-contrast observations and weigh its pros and cons. Furthermore, I will highlight some of the key results to date and explore the future prospects of this technique.