Yolanda Frensch
IA

Abstract
Gas giants around low-mass stars are rare. However, they do exist, challenging current models of planet formation. To find and characterise them, we need to push our instruments to their limits: M dwarfs are intrinsically faint in the visible, while near-infrared spectroscopy introduces challenges such as fiber modal noise and telluric contamination.

I will introduce NIRPS, the near-infrared spectrograph installed alongside HARPS on the ESO 3.6-m telescope, and discuss its commissioning, performance, and the techniques used to mitigate modal noise and tellurics. Building on our understanding of these instrumental limits, we initiated a TESS follow-up program to search for gas giants transiting faint M dwarfs, complemented by a CORALIE survey targeting late-K dwarfs. I will present the main results of these two programs, whose discoveries reveal tentative trends in the giant-planet population toward lower stellar masses: giant-planet mass appears to decrease with effective temperature, while high metallicity and wide stellar companions may favour their formation.

Finally, I will complement these short-period discoveries with long-period companions found through two decades of HARPS observations. Together, this connects instrumental development, individual discoveries, and planetary demographics across stellar masses and orbital separations.

2026 October 27, 11:00

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto