Astronomy and Astrophysics, volume 645A, 16-16 (2021/1-1)
TOI-519 b: A short-period substellar object around an M dwarf validated using multicolour photometry and phase curve analysis.
PARVIAINEN H., PALLE E., ZAPATERO-OSORIO M.R., NOWAK G., FUKUI A., MURGAS F., NARITA N., STASSUN K.G., LIVINGSTON J.H., COLLINS K.A., HIDALGO SOTO D., BEJAR V.J.S., KORTH J., MONELLI M., MONTANES RODRIGUEZ P., CASASAYAS-BARRIS N., CHEN G., CROUZET N., DE LEON J.P., HERNANDEZ A., KAWAUCHI K., KLAGYIVIK P., KUSAKABE N., LUQUE R., MORI M., NISHIUMI T., PRIETO-ARRANZ J., TAMURA M., WATANABE N., GAN T., COLLINS K.I., JENSEN E.L.N., BARCLAY T., DOTY J.P., JENKINS J.M., LATHAM D.W., PAEGERT M., RICKER G., RODRIGUEZ D.R., SEAGER S., SHPORER A., VANDERSPEK R., VILLASENOR J., WINN J.N., WOHLER B. and WONG I.
Abstract (from CDS):
Context. We report the discovery of TOI-519 b (TIC 218795833), a transiting substellar object (R=1.07RJup) orbiting a faint M dwarf (V=17.35) on a 1.26d orbit. Brown dwarfs and massive planets orbiting M dwarfs on short-period orbits are rare, but more have already been discovered than expected from planet formation models. TOI-519 is a valuable addition to this group of unlikely systems, and it adds towards our understanding of the boundaries of planet formation.
Aims. We set out to determine the nature of the Transiting Exoplanet Survey Satellite (TESS) object of interest TOI-519 b.
Methods. Our analysis uses a SPOC-pipeline TESS light curve from Sector 7, multicolour transit photometry observed with MuSCAT2 and MuSCAT, and transit photometry observed with the LCOGT telescopes. We estimated the radius of the transiting object using multicolour transit modelling, and we set upper limits for its mass, effective temperature, and Bond albedo using a phase curve model that includes Doppler boosting, ellipsoidal variations, thermal emission, and reflected light components.
Results. TOI-519 b is a substellar object with a radius posterior median of 1.07RJup and 5th and 95th percentiles of 0.66 and 1.20RJup, respectively, where most of the uncertainty comes from the uncertainty in the stellar radius. The phase curve analysis sets an upper effective temperature limit of 1800K, an upper Bond albedo limit of 0.49, and a companion mass upper limit of 14MJup. The companion radius estimate combined with the Teff and mass limits suggests that the companion is more likely a planet than a brown dwarf, but a brown-dwarf scenario is a priori more likely given the lack of known massive planets in ≃1 day orbits around M dwarfs with Teff<3800K, and given the existence of some (but few) brown dwarfs.
© ESO 2020
stars: individual: TIC 218795833 - planets and satellites: general - methods: statistical - techniques: photometric
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