3D configuration of a compact multi-giant system lying at the stability boundary

The compact multi-giant system WASP-148, harboring a transiting hot Jupiter and a nearby non-transiting warm Jupiter, offers a unique opportunity to understand the formation and evolution of short-period gas giants. In this talk, I will present the 3D configuration of the system, which includes: 1). The Rossiter-McLaughlin effect measurements of WASP-148 b observed with WIYN/NEID and Keck/HIRES indicate an aligned orbit. It is one of the few R-M measurements for compact multi-planet systems. It is also considered one of the first scientific results from the NEID instrument. 2). Mutual inclination of two planets is determined by simultaneously modeling the archived and our newly-collected transit, radial-velocity, and transit timing variation data. Our work suggests a mutual inclination of 26.5^+5.3_-6.6 degrees and stable configuration, whereas the best fit from the previous study indicates a mutual inclination of 41.0^+6.2_-7.6 degrees with a probability being stable of only 2.5%. Our stability analysis shows WASP-148 lies right at its stability boundary, suggesting it is in a transition phase between purely quiescent compact multi-planet systems and dynamically violent isolated-planet systems. The 3D configuration of WASP-148 derived from our work provides observational evidence to support a unified theory of exoplanet formation that can link the configurations we found in compact multi-planet and isolated-Jupiter systems.