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Register a new userThree Short Period Jupiters from TESS
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Added by
Louise Dyregaard Nielsen
Publication date
2020
fields
Physics
and research's language is
English
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We 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 Mjup planet in a grazing transit configuration with an impact parameter of b = 1.17 +0.10/-0.08. As a result the radius is poorly constrained, 2.03 +0.61/-0.49 Rjup. The planets 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 Qs = 10^7 - 10^9. 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 Mjup and a radius of 1.29 +/- 0.02 Rjup. 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 Mjup and a radius of 1.09 +0.08/-0.05 Rjup. 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 - 0.24.
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We report the discovery of two short-period massive giant planets from NASAs Transiting Exoplanet Survey Satellite (TESS). Both systems, TOI-558 (TIC 207110080) and TOI-559 (TIC 209459275), were identified from the 30-minute cadence Full Frame Images and confirmed using ground-based photometric and spectroscopic follow-up observations from TESSs Follow-up Observing Program Working Group. We find that TOI-558 b, which transits an F-dwarf ($M_{star}=1.349^{+0.064}_{-0.065} M_{odot}$, $R_{star}=1.496^{+0.042}_{-0.040} R_{odot}$, $T_{eff}=6466^{+95}_{-93}$ K, age $1.79^{+0.91}_{-0.73}$ Gyr) with an orbital period of 14.574 days, has a mass of $3.61pm0.15 M_J$, a radius of $1.086^{+0.041}_{-0.038} R_J$, and an eccentric (e=$0.300^{+0.022}_{-0.020}$) orbit. TOI-559 b transits a G-dwarf ($M_{star}=1.026pm0.057 M_{odot}$, $R_{star}=1.233^{+0.028}_{-0.026} R_{odot}$, $T_{eff}=5925^{+85}_{-76}$ K, age $1.79^{+0.91}_{-0.73}$ Gyr) in an eccentric (e=$0.151pm0.011$) 6.984-day orbit with a mass of $6.01^{+0.24}_{-0.23} M_J$ and a radius of $1.091^{+0.028}_{-0.025} R_J$. Our spectroscopic follow-up also reveals a long-term radial velocity trend for TOI-559, indicating a long-period companion. The statistically significant orbital eccentricity measured for each system suggests that these planets migrated to their current location through dynamical interactions. Interestingly, both planets are also massive ($>3 M_J$), adding to the population of massive hot Jupiters identified by TESS. Prompted by these new detections of high-mass planets, we analyzed the known mass distribution of hot Jupiters but find no significant evidence for multiple populations. TESS should provide a near magnitude-limited sample of transiting hot Jupiters, allowing for future detailed population studies.
We report the discovery of TOI 263.01 (TIC 120916706), a transiting substellar object (R = 0.87 RJup) orbiting a faint M3.5~V dwarf (V=18.97) on a 0.56~d orbit. We set out to determine the nature of the TESS planet candidate TOI 263.01 using ground-based multicolour transit photometry. The host star is faint, which makes RV confirmation challenging, but the large transit depth makes the candidate suitable for validation through multicolour photometry. Our analysis combines three transits observed simultaneously in r, i, and z_s bands using the MuSCAT2 multicolour imager, three LCOGT-observed transit light curves in g, r, and i bands, a TESS light curve from Sector 3, and a low-resolution spectrum for stellar characterisation observed with the ALFOSC spectrograph. We model the light curves with PyTransit using a transit model that includes a physics-based light contamination component that allows us to estimate the contamination from unresolved sources from the multicolour photometry. This allows us to derive the true planet-star radius ratio marginalised over the contamination allowed by the photometry, and, combined with the stellar radius, gives us a reliable estimate of the objects absolute radius. The ground-based photometry excludes contamination from unresolved sources with a significant colour difference to TOI 263. Further, contamination from sources of same stellar type as the host is constrained to levels where the true radius ratio posterior has a median of 0.217. The median radius ratio corresponds to an absolute planet radius of 0.87 RJup, which confirms the substellar nature of the planet candidate. The object is either a giant planet or a brown dwarf (BD) located deep inside the so-called brown dwarf desert. Both possibilities offer a challenge to current planet/BD formation models and makes 263.01 an object deserving of in-depth follow-up studies.
WASP-12 b, WASP-33 b, WASP-36 b, and WASP-46 b are four transiting planetary systems which we have studied. These systems light curves were derived from observations made by the Transiting Light Exoplanet Survey Satellite (TESS) and some ground-based telescopes. We used Exofast-v1 to model these light curves and calculate mid-transit times. Also, we plotted TTV diagrams for them using derived mid-transit times and those available within the literature. O-C analysis of these timings enables us to refine the linear ephemeris of four systems. We measured WASP-12s tidal quality factor based on adding TESS data as Q*=(2.13+-0.29)*10^5. According to the analysis, the orbital period of the WASP-46 b system is increasing. The WASP-36 b and WASP-33 b systems have not shown any obvious quadratic trend in their TTV diagrams. The increase in their period is most likely due to inaccurate liner ephemeris that has increased over time. So, more observations are needed to evaluate whether or not there is an orbital decay in the WASP-36 b and WASP-33 b systems.
Several authors have shown that precise measurements of transit time variations of exoplanets can be sensitive to other planetary bodies, such as exo-moons. In addition, the transit timing variations of the exoplanets closest to their host stars can provide tests of tidal dissipation theory. These studies, however, have not considered the effect of the host star. There is a large body of observational evidence that eclipse times of binary stars can vary dramatically due to variations in the quadrupole moment of the stars driven by stellar activity. In this paper we investigate and estimate the likely impact such variations have on the transit times of exoplanets. We find in several cases that such variations should be detectable. In particular, the estimated period changes for WASP-18b are of the same order as those expected for tidal dissipation, even for relatively low values of the tidal dissipation parameter. The transit time variations caused by the Applegate mechanism are also of the correct magnitude and occur on timescales such that they may be confused with variations caused by light-time travel effects due to the presence of a Jupiter-like second planet. Finally, we suggest that transiting exoplanet systems may provide a clean route (compared to binaries) to constraining the type of dynamo operating in the host star.
We present the discovery of two new 10-day period giant planets from the Transiting Exoplanet Survey Satellite ($TESS$) mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481 b and TOI-892 b have similar radii ($0.99pm0.01$ $rm R_{J}$ and $1.07pm0.02$ $rm R_{J}$, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses ($1.53pm0.03$ $rm M_{J}$ versus $0.95pm0.07$ $rm M_{J}$, respectively). Both planets orbit metal-rich stars ([Fe/H]= $+0.26pm 0.05$ dex and [Fe/H] = $+0.24 pm 0.05$ dex, for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a $rm M_{star}$ = $1.14pm0.02$ $rm M_{odot}$, $rm R_{star}$ = $1.66pm0.02$ $rm R_{odot}$ G-type star ($T_{rm eff}$ = $5735 pm 72$ 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 ($T_{rm eff}$ = $6261 pm 80$ K), which has a mass of $rm M_{star}$ = $1.28pm0.03$ $rm M_{odot}$, and a radius of $rm R_{star}$ = $1.39pm0.02$ $rm R_{odot}$. 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.
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