Determine the nature of WISPIT 2 b’s thermal emission

Determine whether the observed spectral energy distribution of the protoplanet WISPIT 2 b is adequately described by a single blackbody or instead requires an atmospheric model, using longer-wavelength and higher-resolution observations.

Background

The paper combines GRAVITY+ medium-resolution K-band spectroscopy with SPHERE and LBTI photometry to model the thermal emission of WISPIT 2 b. Atmospheric models, particularly Exo-REM and DRIFT-PHOENIX, provide better fits than a single blackbody, but the available spectral and photometric coverage is sparse and the preference is not definitive.

The unresolved issue is whether the apparent flat spectral energy distribution reflects atmospheric effects such as clouds and molecular absorption or can still be explained by a blackbody. The authors identify mid-infrared observations with JWST/MIRI or ELT/METIS as the means of testing for diagnostic CO, H2O, and silicate features.

References

With the available data, we were unable to significantly rule out a single blackbody as the best fit to the observed SED of WISPIT 2 b.

— A first look at the protoplanet WISPIT 2 b with VLTI/GRAVITY+  (2610.21629 - Collaboration et al., 15 Oct 2026) in Section 3.4, “Constraining the nature of WISPIT 2 b in the mid-infrared”