2025A&A...699A.237G

Context. The multitude of different architectures found for evolved exoplanet systems are in all likelihood set during the initial planet-formation phase in the circumstellar disk. To understand this process, we have to study the earliest phases of planet formation.
Aims. Complex sub-structures, believed to be driven by embedded planets, have been detected in a significant portion of the disks observed at high angular resolution. We aim to extend the sample of such disks to low stellar masses and to connect the disk morphology to the expected proto-planet properties.
Methods. In this study, we used VLT/SPHERE to obtain resolved images on the scale of ∼10 au of the circumstellar disk in the 2MASSJ16120668-3010270 system in polarized scattered light. We searched for the thermal radiation of recently formed gas giants embedded in the disk. Additionally, we used VLT/XSHOOTER to obtain the stellar properties in the system.
Results. We resolve the disk in the 2MASSJ16120668-3010270 system for the first time in scattered near-infrared light and reveal an exceptionally structured disk. We find an inner disk (reaching out to 40 au) with two spiral arms, separated by a gap from an outer ring extending to 115 au. By comparison with our own model and hydrodynamic models from the literature, we find that these structures are consistent with the presence of an embedded gas giant with a mass range between 0.1 M_Jup and 5 M_Jup depending on the employed model and their underlying assumptions. Our SPHERE observations find a tentative candidate point source within the disk gap, the brightness of which would be consistent with this mass range if it indeed traces thermal emission by an embedded planet. This interpretation is somewhat strengthened by the proximity of this signal to compact millimeter continuum emission in the disk gap, which may trace circumplanetary material. It is, however, unclear if this tentative companion candidate could be responsible for the observed disk gap size, given its close proximity to the inner disk. Generally, our VLT/SPHERE observations set an upper limit of ∼5 M_Jup in the disk gap (∼0.2”-0.5”), consistently with our modeling results. The 2MASSJ16120668-3010270 system is one of only a few systems that shows this exceptional morphology of spiral arms located inside a scattered light gap and ring. We speculate that this may have to do with a higher disk viscosity compared with other systems such as PDS 70. If planets in the disk are confirmed, 2MASSJ16120668-3010270 will become a prime laboratory for the study of planet-disk interaction.