TOI-4010: A System of Three Large Short-Period Planets With a Massive Long-Period Companion

We report the confirmation of three exoplanets transiting TOI-4010 (TIC-352682207), a metal-rich K dwarf observed by TESS in Sectors 24, 25, 52, and 58. We confirm these planets with HARPS-N radial velocity observations and measure their masses with 8 - 12% precision. TOI-4010 b is a sub-Neptune ($P=1.3$ days, $R_p=3.02_{-0.08}^{+0.08}{R}_{\oplus }$, $M_p=11.00_{-1.27}^{+1.29}{M}_{\oplus }$) in the hot Neptune desert, and is one of the few such planets with known companions. Meanwhile, TOI-4010 c ($P=5.4$ days, $R_p=5.93_{-0.12}^{+0.11}{R}_{\oplus }$, $M_p=20.31_{-2.11}^{+2.13}{M}_{\oplus }$) and TOI-4010 d ($P=14.7$ days, $R_p=6.18_{-0.14}^{+0.15}{R}_{\oplus }$, $M_p=38.15_{-3.22}^{+3.27}{M}_{\oplus }$) are similarly-sized sub-Saturns on short-period orbits. Radial velocity observations also reveal a super-Jupiter-mass companion called TOI-4010 e in a long-period, eccentric orbit ($P\sim 762$ days and $e\sim 0.26$ based on available observations). TOI-4010 is one of the few systems with multiple short-period sub-Saturns to be discovered so far.