nu2 Lupi CHEOPS light curves

The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. nu^2^ Lupi (HD 136352) is a naked-eye (V=5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6 and 107.6d via radial-velocity monitoring.

The two inner planets (b and c) were recently found to transit2, prompting a photometric follow-up by the brand new Characterising Exoplanets Satellite (CHEOPS). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be 2.56+/-0.09R_{Earth}_ and 8.82+/-0.94M_{Earth}_, respectively. With its bright Sun-like star, long period and mild irradiation (~5.7 times the irradiation of Earth), nu^2^ Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization.