Titol: Helium as a window into exoplanet atmospheres and stellar environment

Lloc: Seminari del DAA. Edifici Investigació Jeroni Muñoz, planta quarta, a Burjassot.

Dia: dimecres, 6 de maig de 2026. Hora: 12:00.

Resum:

Since 2018, the University of Texas at Austin has been conducting an extensive survey of exoplanet atmospheres using the Habitable-zone Planet Finder (HPF) on the 10m Hobby-Eberly Telescope (HET). Leveraging the HET’s large collecting area and the HPF’s high spectral resolution and stability, the program has focused on observations of the Helium triplet at 1083nm, a powerful tracer of extended atmospheres and atmospheric escape in close-in exoplanets. Helium transmission spectroscopy provides information for several aspects of planetary properties and demographics:

i) Influence of different atmospheric escape regimes: bubble vs stream evaporation in the exoplanet population. Distinguishing between these two scenarios is critical to avoiding misinterpretation of planetary absorption and mass loss rates.

ii) Atmospheric formation and early planetary evolution. Only Helium observations of young exoplanets can test atmospheric formation theories, and constrain the timescales predicted.

iii) Star-planet interaction. Atmospheric escape is mainly driven by stellar irradiation, which varies throughout different stellar cycles. Thus, Helium observations provide a valuable opportunity to study the relationship between an exoplanet's atmosphere and its host star.


We will place HET/HPF results in the broader context of space- and ground-based Helium surveys and summarize the main observational trends that have emerged from the different programs. Finally, we will outline future opportunities for Helium science with HET/HPF to address remaining open questions in the field.