200,930 research outputs found
TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf
No full textWe present the discovery of two exoplanets transiting TOI-836 (TIC 440887364) using data from TESS Sector 11 and Sector 38. TOI-836 is a bright (T = 8.5 mag), high proper motion (∼200 mas yr−1), low metallicity ([Fe/H]≈−0.28) K-dwarf with a mass of 0.68 ± 0.05 M⊙ and a radius of 0.67 ± 0.01 R⊙. We obtain photometric follow-up observations with a variety of facilities, and we use these data sets to determine that the inner planet, TOI-836 b, is a 1.70 ± 0.07 R⊕ super-Earth in a 3.82-d orbit, placing it directly within the so-called ‘radius valley’. The outer planet, TOI-836 c, is a 2.59 ± 0.09 R⊕ mini-Neptune in an 8.60-d orbit. Radial velocity measurements reveal that TOI-836 b has a mass of 4.5 ± 0.9 M⊕, while TOI-836 c has a mass of 9.6 ± 2.6 M⊕. Photometric observations show Transit Timing Variations (TTVs) on the order of 20 min for TOI-836 c, although there are no detectable TTVs for TOI-836 b. The TTVs of planet TOI-836 c may be caused by an undetected exterior planet.</p
TOI-481 b and TOI-892 b: Two Long-period Hot Jupiters from the Transiting Exoplanet Survey Satellite
No full textWe present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481 b and TOI-892 b have similar radii (0.99 ± 0.01 R_J and 1.07 ± 0.02 R_J, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses (1.53 ± 0.03 M_J versus 0.95 ± 0.07 M_J, respectively). Both planets orbit metal-rich stars ([Fe/H] = +0.26 ± 0.05 dex and [Fe/H] = +0.24 ± 0.05 for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a M⋆ = 1.14 ± 0.02 M_⊙, R⋆ = 1.66 ± 0.02 R_⊙ G-type star (T_(eff) = 5735 ± 72 K), that with an age of 6.7 Gyr, is in the turn-off point of the main sequence. TOI-892 on the other hand, is a F-type dwarf star (T_(eff) = 6261 ± 80 K), which has a mass of M⋆ = 1.28 ± 0.03 M_⊙ and a radius of R⋆ = 1.39 ± 0.02 R_⊙. TOI-481 b and TOI-892 b join the scarcely populated region of transiting gas giants with orbital periods longer than 10 days, which is important to constrain theories of the formation and structure of hot Jupiters
TOI-811b and TOI-852b: New Transiting Brown Dwarfs with Similar Masses and Very Different Radii and Ages from the TESS Mission
No full textWe report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASA's 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 Mb = 59.9 ± 13.0MJ and radius of Rb = 1.26 ± 0.06RJ, and it orbits its host star in a period of P = 25.16551 ± 0.00004 days. We derive the host star's age of 93+61-29 Myr from an application of gyrochronology. The youth of this system, rather than external heating from its host star, is why this BD's radius is relatively large. This constraint on the youth of TOI-811b allows us to test substellar mass-radius evolutionary models at young ages where the radius of BDs changes rapidly. TOI-852b has a similar mass at Mb = 53.7 ± 1.4MJ but is much older (4 or 8 Gyr, based on bimodal isochrone results of the host star) and is also smaller with a radius of Rb = 0.83 ± 0.04RJ. TOI-852b's orbital period is P = 4.94561 ± 0.00008 days. TOI-852b joins the likes of other old transiting BDs that trace out the oldest substellar mass-radius evolutionary models where contraction of the BD's radius slows and approaches a constant value. Both host stars have a mass of M∗ = 1.32M⊙ ± 0.05 and differ in their radii, Teff, and [Fe/H], with TOI-811 having R∗ = 1.27 ± 0.09R⊙, Teff = 6107 ± 77 K, and [Fe/ H]=+0.40 ± 0.09 and TOI-852 having R∗ = 1.71 ± 0.04R⊙, Teff = 5768 ± 84 K, and [Fe/H]=+0.33 ± 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
A super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270
No full textpeer reviewedOne of the primary goals of exoplanetary science is to detect small, temperate planets passing (transiting) in front of bright and quiet host stars. This enables the characterization of planetary sizes, orbits, bulk compositions, atmospheres and formation histories. These studies are facilitated by small and cool M dwarf host stars. Here we report the Transiting Exoplanet Survey Satellite (TESS)[SUP]1[/SUP] discovery of three small planets transiting one of the nearest and brightest M dwarf hosts observed to date, TOI-270 (TIC 259377017, with K-magnitude 8.3, and 22.5 parsecs away from Earth). The M3V-type star is transited by the super-Earth-sized planet TOI-270 b (1.247[SUB]-0.083[/SUB][SUP]+0.089[/SUP]R[SUB]⊕[/SUB]) and the sub- Neptune-sized planets TOI-270 c (2.42 ± 0.13 R[SUB]⊕[/SUB]) and TOI-270 d (2.13 ± 0.12 R[SUB]⊕[/SUB]). The planets orbit close to a mean-motion resonant chain, with periods (3.36 days, 5.66 days and 11.38 days, respectively) near ratios of small integers (5:3 and 2:1). TOI-270 is a prime target for future studies because (1) its near-resonance allows the detection of transit timing variations, enabling precise mass measurements and dynamical studies; (2) its brightness enables independent radial-velocity mass measurements; (3) the outer planets are ideal for atmospheric characterization via transmission spectroscopy; and (4) the quietness of the star enables future searches for habitable zone planets. Altogether, very few systems with small, temperate exoplanets are as suitable for such complementary and detailed characterization as TOI-270
TOI-333b: A Neptune-desert planet around an F7V star
No full textObservations have shown that planets similar to Neptune are rarely found orbiting Sun-like stars with periods up to ∼4 days. This defines the so-called Neptune desert region. The detection of each individual planet in this region therefore holds a high value by providing detailed insights into the formation and evolution of this population. We report the detection of TOI-333b, a Neptune-desert planet with a mass, radius, and bulk density of 20.1 ± 2.4 M
⊕
, 4.26 ± 0.11 R
⊕
, and 1.42 ± 0.21 g cm
−3
. The planet orbits an F7V star every 3.78 d, whose mass, radius, and effective temperature are of 1.2 ± 0.1 M
⊙
, 1.10 ± 0.03 R
⊙
, and 6241
−62
+73
K, respectively. TOI-333bis likely younger than 1 Gyr, which is supported by the doublet Li line around 6707.856 Å and its comparison to Li abundances in open clusters with well-constrained ages. The planet is expected to host only a 8.5
−8.3
+10.9
% gas-to-core mass ratio for an H/He envelope. On the other hand, models of irradiated ocean worlds predict a 20
−10
+11
% H
2
O mass fraction with a core fraction of 35
−23
+20
%. We therefore expect that the internal composition of TOI-333bis dominated by a pure rocky composition with almost no H/He envelope, or a rocky world with almost equal mass fraction of water. Finally, TOI-333bis more massive and larger than 77% and 82% of its Neptune-desert counterparts, and its host ranks among the hottest known stars for Neptune-desert planets. This makes this system a unique laboratory for studying the evolution of these planets around hot stars.</p
Three short-period Earth-sized planets around M dwarfs discovered by TESS: TOI-5720 b, TOI-6008 b, and TOI-6086 b
No full textOne of the main goals of the NASA Transiting Exoplanet Survey Satellite (TESS) mission is the discovery of Earth-like planets around nearby M-dwarf stars. We present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M dwarfs: TOI-5720 b, TOI-6008 b, and TOI-6086 b. We combined TESS data, ground-based multicolor light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD radial velocity data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720 b is an Earth-sized planet with a radius of Rp = 1.09 ± 0.07 R⊕. It orbits a nearby (36 pc) M 2.5 host with an orbital period of P = 1.4344555 ± 0.0000036 days. It has an equilibrium temperature of Teq = 708 ± 19 K (assuming a null albedo) and an incident flux of Sp = 41.7 ± 4.5 S⊕. TOI-6008 b is a short-period planet of P = 0.8574347 ± 0.0000424 day. It has a radius of Rp = 1.03 ± 0.05 R⊕, an equilibrium temperature of Teq = 707 ± 19 K, and an incident flux of Sp = 41.5 ± 4.5 S⊕. The host star (TOI-6008) is a nearby (23 pc) M 5 with an effective temperature of Teff = 3075 ± 75 K. Based on the radial velocity measurements collected with Subaru/IRD, we set a 3σ upper limit of Mp < 4 M⊕, thus ruling out a star or brown dwarf as the transiting companion. TOI-6086 b orbits its nearby (32 pc) M 3 host star (Teff = 3200 ± 75 K) every 1.3888725 ± 0.0000827 days and has a radius of Rp = 1.18 ± 0.07 R⊕, an equilibrium temperature of Teq = 634 ± 16 K, and an incident flux of Sp = 26.8 ± 2.7 S⊕. Additional high-precision radial velocity measurements are needed to derive the planetary masses and bulk densities and to search for additional planets in the systems. Moreover, short-period Earth-sized planets orbiting around nearby M dwarfs are suitable targets for an atmospheric characterization with the James Webb Space Telescope through transmission and emission spectroscopy and phase-curve photometry
TOI 564 b and TOI 905 b: Grazing and Fully Transiting Hot Jupiters Discovered by TESS
No full textWe 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 MJ and a radius of 1.02+0.71/−0.29 RJ. TOI 905 b is a classical hot Jupiter as well, with a mass of 0.667+0.042/−0.041 MJ and radius of 1.171+0.053/−0.051 RJ. 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
Two sub-Neptunes around the M dwarf TOI-1470
No full textAims. A transiting planet candidate with a sub-Neptune radius orbiting the nearby ( d = 51.9 ± 0.07 pc) M1.5 V star TOI-1470 with a period of ~2.5 d was announced by the NASA Transiting Exoplanet Survey Satellite (TESS), which observed the field of TOI-1470 in four different sectors. We aim to validate its planetary nature using precise radial velocities (RVs) taken with the CARMENES spectrograph. Methods. We obtained 44 RV measurements with CARMENES spanning eight months between 3 June 2020 and 17 January 2021. For a better characterization of the parent star activity, we also collected contemporaneous optical photometric observations at the Joan Oró and Sierra Nevada Observatories, and we retrieved archival photometry from the literature. We used ground-based photometric observations from MuSCAT and also from MuSCAT2 and MuSCAT3 to confirm the planetary transit signals. We performed a combined photometric and spectroscopic analysis by including Gaussian processes and Keplerian orbits to simultaneously account for the stellar activity and planetary signals. Results. We estimate that TOI-1470 has a rotation period of 29 ± 3d based on photometric and spectroscopic data. The combined analysis confirms the discovery of the announced transiting planet, TOI-1470 b, with an orbital period of 2.527093 ± 0.000003 d, a mass of 7.32 -1.24 +1.21 M ⊕ , and a radius of 2.18 -0.04 +0.04 R ⊕ . We also discover a second transiting planet that was not announced previously by TESS, TOI-1470 c, with an orbital period of 18.08816 ± 0.00006 d, a mass of 7.24 -2.77 +2.87 M ⊕ , and a radius of 2.47 -0.02 +0.02 R ⊕ . The two planets are placed on the same side of the radius valley of M dwarfs and lie between TOI-1470 and the inner border of its habitable zone
TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet
No full textWe present the bright (Vmag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 ± 0.7 d using archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431 b is a super-Earth with a period of 0.49 d, a radius of 1.28 ± 0.04 R, a mass of 3.07 ± 0.35 M, and a density of 8.0 ± 1.0 g cm-3; TOI-431 d is a sub-Neptune with a period of 12.46 d, a radius of 3.29 ± 0.09 R, a mass of 9.90+1.53-1.49 M, and a density of 1.36 ± 0.25 g cm-3. We find a third planet, TOI-431 c, in the High Accuracy Radial velocity Planet Searcher RV data, but it is not seen to transit in the TESS light curves. It has an Msin i of 2.83+0.41-0.34 M, and a period of 4.85 d. TOI-431 d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431 b may be a stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431 b is a prime TESS discovery for the study of rocky planet phase curves
Three short-period Jupiters from TESS. HIP 65Ab, TOI-157b, and TOI-169b
No full textpeer reviewedWe report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 M[SUB]J[/SUB] planet in a grazing transit configuration with an impact parameter of b = 1.17[SUB]-0.08[/SUB][SUP]+0.10[/SUP]. As a result the radius is poorly constrained, 2.03[SUB]-0.49[/SUB][SUP]+0.61[/SUP]R[SUB]J[/SUB]. The planet's distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Q[SUB]s[/SUB][SUP]'[/SUP] = 10[SUP]7[/SUP] - 10[SUP]9[/SUP]. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13 M[SUB]J[/SUB] and a radius of 1.29 ± 0.02 R[SUB]J[/SUB]. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06 M[SUB]J[/SUB] and a radius of 1.09[SUB]-0.05[/SUB][SUP]+0.08[/SUP]R[SUB]J[/SUB]. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to0.24
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