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Register a new userTOI-811b and TOI-852b: New transiting brown dwarfs with similar masses and very different radii and ages from the TESS mission
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We report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASAs Transiting Exoplanet Survey Satellite mission. These two transiting BDs have similar masses, but very different radii and ages. Their host stars have similar masses, effective temperatures, and metallicities. The younger and larger transiting BD is TOI-811b at a mass of $M_b = 55.3 pm 3.2{rm M_J}$ and radius of $R_b = 1.35 pm 0.09{rm R_J}$ and it orbits its host star in a period of $P = 25.16551 pm 0.00004$ days. Its age of $93^{+61}_{-29}$ Myr, which we derive from an application of gyrochronology to its host star, is why this BDs radius is relatively large, not heating from its host star since this BD orbits at a longer orbital period than most known transiting BDs. This constraint on the youth of TOI-811b allows us to test substellar mass-radius isochrones where the radius of BDs changes rapidly with age. TOI-852b is a much older (4.0 Gyr from stellar isochrone models of the host star) and smaller transiting BD at a mass of $M_b = 53.7 pm 1.3{rm M_J}$, a radius of $R_b = 0.75 pm 0.03{rm R_J}$, and an orbital period of $P = 4.94561 pm 0.00008$ days. TOI-852b joins the likes of other old transiting BDs that trace out the oldest substellar mass-radius isochrones where contraction of the BDs radius asymptotically slows. Both host stars have a mass of $M_star = 1.32{rm M_odot}pm0.05$ and differ in their radii, $T_{rm eff}$, and [Fe/H] with TOI-811 having $R_star=1.27pm0.09{rm R_odot}$, $T_{rm eff} = 6107 pm 77$K, and $rm [Fe/H] = +0.40 pm 0.09$ and TOI-852 having $R_star=1.71pm0.04{rm R_odot}$, $T_{rm eff} = 5768 pm 84$K, and $rm [Fe/H] = +0.33 pm 0.09$. We take this opportunity to examine how TOI-811b and TOI-852b serve as test points for young and old substellar isochrones, respectively.
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We report the discovery of two intermediate-mass brown dwarfs (BDs), TOI-569b and TOI-1406b, from NASAs Transiting Exoplanet Survey Satellite mission. TOI-569b has an orbital period of $P = 6.55604 pm 0.00016$ days, a mass of $M_b = 64.1 pm 1.9 M_J$, and a radius of $R_b = 0.75 pm 0.02 R_J$. Its host star, TOI-569, has a mass of $M_star = 1.21 pm 0.03 M_odot$, a radius of $R_star = 1.47 pm 0.03 R_odot$, $rm [Fe/H] = +0.29 pm 0.09$ dex, and an effective temperature of $T_{rm eff} = 5768 pm 110K$. TOI-1406b has an orbital period of $P = 10.57415 pm 0.00063$ days, a mass of $M_b =46.0 pm 2.7 M_J$, and a radius of $R_b = 0.86 pm 0.03 R_J$. The host star for this BD has a mass of $M_star =1 .18 pm 0.09 M_odot$, a radius of $R_star = 1.35 pm 0.03 R_odot$, $ rm [Fe/H] = -0.08 pm 0.09$ dex and an effective temperature of $T_{rm eff} = 6290 pm 100K$. Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI-569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI-415). TOI-1406b is one of three known transiting BDs to occupy the mass range of $40-50 M_J$ and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b).Both BDs have reliable ages from stellar isochrones in addition to their well-constrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD mass-radius diagram.
We report the discovery of an intermediate-mass transiting brown dwarf, TOI-503b, from the TESS mission. TOI-503b is the first brown dwarf discovered by TESS and orbits a metallic-line A-type star with a period of $P=3.6772 pm 0.0001$ days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the brown dwarfs radius ($R_b = 1.34^{+0.26}_{-0.15} R_J$). We obtained high-resolution spectroscopic observations with the FIES, Ondv{r}ejov, PARAS, Tautenburg, and TRES spectrographs and measured the mass of TOI-503b to be $M_b = 53.7 pm 1.2 M_J$. The host star has a mass of $M_star = 1.80 pm 0.06 M_odot$, a radius of $R_star = 1.70 pm 0.05 R_odot$, an effective temperature of $T_{rm eff} = 7650 pm 160$K, and a relatively high metallicity of $0.61pm 0.07$ dex. We used stellar isochrones to derive the age of the system to be $sim$180 Myr, which places its age between that of RIK 72b (a $sim$10 Myr old brown dwarf in the Upper Scorpius stellar association) and AD 3116b (a $sim$600 Myr old brown dwarf in the Praesepe cluster). We argue that this brown dwarf formed in-situ, based on the young age of the system and the long circularization timescale for this brown dwarf around its host star. TOI-503b joins a growing number of known short-period, intermediate-mass brown dwarfs orbiting main sequence stars, and is the second such brown dwarf known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the brown dwarf desert ($35-55 M_J sin{i}$) is reforesting and its mass range shrinking.
We report the discovery and confirmation of two new hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS): TOI 564 b and TOI 905 b. The transits of these two planets were initially observed by TESS with orbital periods of 1.651 d and 3.739 d, respectively. We conducted follow-up observations of each system from the ground, including photometry in multiple filters, speckle interferometry, and radial velocity measurements. For TOI 564 b, our global fitting revealed a classical hot Jupiter with a mass of $1.463^{+0.10}_{-0.096} M_J$ and a radius of $1.02^{+0.71}_{-0.29} R_J$. TOI 905 b is a classical hot Jupiter as well, with a mass of $0.667^{+0.042}_{-0.041} M_J$ and radius of $1.171^{+0.053}_{-0.051} R_J$. Both planets orbit Sun-like, moderately bright, mid-G dwarf stars with V ~ 11. While TOI 905 b fully transits its star, we found that TOI 564 b has a very high transit impact parameter of $0.994^{+0.083}_{-0.049}$, making it one of only ~20 known systems to exhibit a grazing transit and one of the brightest host stars among them. TOI 564 b is therefore one of the most attractive systems to search for additional non-transiting, smaller planets by exploiting the sensitivity of grazing transits to small changes in inclination and transit duration over the time scale of several years.
We report the detection of the first circumbinary planet found by TESS. The target, a known eclipsing binary, was observed in sectors 1 through 12 at 30-minute cadence and in sectors 4 through 12 at two-minute cadence. It consists of two stars with masses of 1.1 MSun and 0.3 MSun on a slightly eccentric (0.16), 14.6-day orbit, producing prominent primary eclipses and shallow secondary eclipses. The planet has a radius of ~6.9 REarth and was observed to make three transits across the primary star of roughly equal depths (~0.2%) but different durations -- a common signature of transiting circumbinary planets. Its orbit is nearly circular (e ~ 0.09) with an orbital period of 95.2 days. The orbital planes of the binary and the planet are aligned to within ~1 degree. To obtain a complete solution for the system, we combined the TESS photometry with existing ground-based radial-velocity observations in a numerical photometric-dynamical model. The system demonstrates the discovery potential of TESS for circumbinary planets, and provides further understanding of the formation and evolution of planets orbiting close binary stars.
We report the discovery and validation of TOI 122b and TOI 237b, two warm planets transiting inactive M dwarfs observed by textit{TESS}. Our analysis shows TOI 122b has a radius of 2.72$pm$0.18 R$_rm{e}$ and receives 8.8$pm$1.0$times$ Earths bolometric insolation, and TOI 237b has a radius of 1.44$pm$0.12 R$_rm{e}$ and receives 3.7$pm$0.5$times$ Earth insolation, straddling the 6.7$times$ Earth insolation that Mercury receives from the sun. This makes these two of the cooler planets yet discovered by textit{TESS}, even on their 5.08-day and 5.43-day orbits. Together, they span the small-planet radius valley, providing useful laboratories for exploring volatile evolution around M dwarfs. Their relatively nearby distances (62.23$pm$0.21 pc and 38.11$pm$0.23 pc, respectively) make them potentially feasible targets for future radial velocity follow-up and atmospheric characterization, although such observations may require substantial investments of time on large telescopes.
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