TOI-1130: A photodynamical analysis of a hot Jupiter in resonance with an inner low-mass planet

The TOI-1130 is a known planetary system around K-dwarf consisting of gas giant planet, c, on an 8.4-day orbit, accompanied by inner Neptune-sized b, with orbital period 4.1 days. We collected precise radial velocity (RV) measurements the HARPS and PFS spectrographs as part our ongoing RV follow-up program. perform photodynamical modeling RVs, transit photometry from Transiting Exoplanet Survey Satellite (TESS) TESS Follow-up Observing Program. determine planet masses radii b c to be Mb = 19.28 $\pm$ 0.97 M$_\oplus$ Rb 3.56 0.13 R$_\oplus$, Mc 325.59 5.59 Rc 13.32+1.55-1.41 respectively. spectroscopically confirm that was previously only validated. find two planets orbit small eccentricities in 2:1 resonant configuration. This first hot Jupiter lower mass locked mean-motion resonance. belongs yet increasing population Jupiters low-mass challenges pathway for formation. also detect linear trend possibly due presence outer massive companion.