Three new brown dwarfs and a massive hot Jupiter revealed by TESS around early-type stars

Abstract

The detection and characterization of exoplanets and brown dwarfs (BDs) around massive AF-type stars is essential to investigate and constrain the impact of stellar mass on planet properties. However, such targets are still poorly explored in radial velocity (RV) surveys because they only feature a small number of stellar lines and those are usually broadened and blended by stellar rotation as well as stellar jitter. As a result, the available information about the formation and evolution of planets and BDs around hot stars is limited. We aim to increase the sample and precisely measure the masses and eccentricities of giant planets and BDs transiting AF-type stars detected by the Transiting Exoplanet Survey Satellite (TESS). We followed bright (V < 12 mag) stars with $T_{\mathrm{eff}}$ > 6200 K that host giant companions (R > 7 ${\mathrm{R}}_{\oplus }$) using ground-based photometric observations as well as high precision RV measurements from the CORALIE, CHIRON, TRES, FEROS, and MINERVA-Australis spectrographs. In the context, we present the discovery of three BD companions, TOI-629b, TOI-1982b, and TOI-2543b, and one massive planet, TOI-1107b. From the joint analysis we find the BDs have masses between 66 and 68 ${\mathrm{M}}_{\mathrm{Jup}}$, periods between 7.54 and 17.17 days, and radii between 0.95 and 1.11 ${\mathrm{R}}_{\mathrm{Jup}}$. The hot Jupiter TOI-1107b has an orbital period of 4.08 days, a radius of 1.30 ${\mathrm{R}}_{\mathrm{Jup}}$, and a mass of 3.35 ${\mathrm{M}}_{\mathrm{Jup}}$. As a by-product of this program, we identified four low-mass eclipsing components (TOI-288b, TOI-446b, TOI-478b, and TOI-764b). Both TOI-1107b and TOI-1982b present an anomalously inflated radius with respect to the age of these systems. TOI-629 is among the hottest stars with a known transiting brown dwarf. TOI-629b and TOI-1982b are among the most eccentric brown dwarfs.

21 pages, 13 figures, Accepted by Astronomy & Astrophysics

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