Direct Spectroscopic Confirmation of the Young Embedded Protoplanet WISPIT 2c

Abstract WISPIT 2 is a nearby young star with a multiringed disk that was recently confirmed to host a ∼4.9 M Jup gas giant planet embedded in a large (60 au) gap at a radial separation of 57 au from the host star. We confirm and characterize a second, close-in planet in the WISPIT 2 system using a combination of new Very Large Telescope/SPHERE H -band dual-polarization imaging and VLTI/GRAVITY K -band interferometric observations of the WISPIT 2 system. The GRAVITY detection is consistent with a point-like source while its extracted K -band spectrum shows CO band-head absorption at 2.3 μ m and a continuum shape consistent with a young giant planet. From the GRAVITY data, we extract a medium resolution K -band spectrum of the companion and fit atmospheric model grids using the species tool with nested sampling to constrain its effective temperature, radius, and luminosity. We infer T eff of 1500–2600 K, a radius of 0.91–2.2 R Jup , and a luminosity of (−3.47)–(−3.63). Comparison with evolutionary tracks implies a mass range of 8–12 M Jup , approximately twice as massive as the previously confirmed WISPIT 2b. The astrometry rules out a background source and marginally detects orbital motion of WISPIT 2 c, which needs further follow-up observations for confirmation. WISPIT 2 now becomes an analog to PDS 70, offering a second laboratory for studying the formation and early evolution of a multiplanet system within its natal disk.