HAT-P-65b AND HAT-P-66b: TWO TRANSITING INFLATED HOT JUPITERS AND OBSERVATIONAL EVIDENCE FOR THE REINFLATION OF CLOSE-IN GIANT PLANETS (original) (raw)
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Monthly Notices of the Royal Astronomical Society, 2014
It is already stated in the previous studies that the radius of the giant planets is affected by stellar irradiation. The confirmed relation between radius and incident flux depends on planetary mass intervals. In this study, we show that there is a single relation between radius and irradiated energy per gram per second (l −), for all mass intervals. There is an extra increase in radius of planets if l − is higher than 1100 times energy received by the Earth (l ⊕). This is likely due to dissociation of molecules. The tidal interaction as a heating mechanism is also considered and found that its maximum effect on the inflation of planets is about 15 per cent. We also compute age and heavy element abundances from the properties of host stars, given in the TEPCat catalogue (Southworth 2011). The metallicity given in the literature is as [Fe/H]. However, the most abundant element is oxygen, and there is a reverse relation between the observed abundances [Fe/H] and [O/Fe]. Therefore, we first compute [O/H] from [Fe/H] by using observed abundances, and then find heavy element abundance from [O/H]. We also develop a new method for age determination. Using the ages we find, we analyse variation of both radius and mass of the planets with respect to time, and estimate the initial mass of the planets from the relation we derive for the first time. According to our results, the highly irradiated gas giants lose 5 per cent of their mass in every 1 Gyr.
Explorations Into the Viability of Coupled Radius-Orbit Evolutionary Models for Inflated Planets
The Astrophysical Journal, 2011
The radii of some transiting extrasolar giant planets are larger than would be expected by the standard theory. We address this puzzle with the model of coupled radius-orbit tidal evolution developed by Ibgui & Burrows (2009). The planetary radius is evolved self-consistently with orbital parameters, under the influence of tidal torques and tidal dissipation in the interior of the planet. A general feature of this model, which we have previously demonstrated in the generic case, is that a possible transient inflation of the planetary radius can temporarily interrupt its standard monotonic shrinking and can lead to the inflated radii that we observe. In particular, a bloated planet with even a circular orbit may still be inflated due to an earlier episode of tidal heating. We have modified our model to include an orbital period dependence of the tidal dissipation factor in the star, Q ′ * ∝ P γ , −1 γ 1. With this model, we search, for a tidally heated planet, orbital and radius evolutionary tracks that fall within the observational limits of the radius, the semimajor axis, and the eccentricity of the planet in its current estimated age range. We find that, for some inflated planets (WASP-6b and WASP-15b), there are such tracks; for another (TrES-4), there are none; and for still others (WASP-4b and WASP-12b), there are such tracks, but our model might imply that we are observing the planets at a special time. Finally, we stress that there is a two to three order-of-magnitude timescale uncertainty of the inspiraling phase of the planet into its host star, arising from uncertainties in the tidal dissipation factor in the star Q ′ * .
Formation of the giant planets
Planetary and Space Science, 1982
Observational constraints on interior models of the giant planets indicate that these planets were all much hotter when they formed and they all have rock and/or ice cores of ten to thirty earth masses. These cores are probably soluble in the envelopes above, especially in Jupiter and Saturn, and are therefore likely to be primordial. They persist despite the continual upward mixing by thermally driven convection throughout the age of the solar system, because of the inefficiency of double-diffusive convection. Thus, these planets most probably formed by the hydrodynamic collapse of a gaseous envelope onto a core rather than by direct instability of the gaseous solar nebula. Recent calculations by Mizuno (1980, Prog. Theor. Phys. 64, 544) show that this formation mechanism may explain the similarity of giant planet core masses. Problems remain however, and no current model is entirely satisfactory in explaining the properties of the giant planets and simultaneously satisfying the terrestrial planet constraints. Satellite systematics and protoplanetary disk nebulae are also discussed and related to formation conditions.
The Astrophysical Journal, 2005
Two extrasolar planets, HD 209458b and TrES-1, are currently known to transit bright parent stars for which physical properties can be accurately determined. The two transiting planets have very similar masses and periods and hence invite detailed comparisons between their observed and theoretically predicted properties. In this paper, we carry out these comparisons. We first report photometric and spectroscopic follow-up observations of TrES-1, and we use these observations to obtain improved estimates for the planetary radius, R pl ¼ (1:08 AE 0:05)R J , and the planetary mass, M pl ¼ (0:729 AE 0:036)M J . We also confirm that the inclination estimate of the planetary orbit as i ¼ 88N2. These values agree with those obtained by Alonso et al. in their discovery paper, but the uncertainty in the planet radius has been improved as a result of both high-cadence photometry of two full transits and from independent radius determinations for the V ¼ 11:8 K0 V parent star. We derive estimates for the TrES-1 stellar parameters of R Ã =R ¼ 0:83 AE 0:03 (by combining independent estimates from stellar models, high-resolution spectra, and transit light curve fitting) M Ã =M ¼ 0:87 AE 0:05 (via fitting to evolutionary tracks), T eA ¼ 5214 AE 23 K , ½Me=H ¼ 0:001 AE 0:04, rotational velocity V sin (i) ¼ 1:08 AE 0:3 km s À1 , log g ¼ 4:52 AE 0:05 dex, log L Ã =L ¼ À0:32, d ¼ 157 AE 6 pc, and an age of ¼ 4 AE 2 Gyr. These estimates of the physical properties of the system allow us to compute evolutionary models for the planet that result in a predicted radius of R pl ¼ 1:05R J for a model that contains an incompressible 20 M È core and a radius R pl ¼ 1:09R J for a model without a core. We use our grids of planetary evolution models to show that, with standard assumptions, our code also obtains good agreement with the observed radii of the other recently discovered transiting planets, including OGLE-TR-56b, OGLE-TR-111b, OGLE-TR-113b, and OGLE-TR-132b. We report an updated radius for HD 209458b of R pl ¼ (1:32 AE 0:05)R J , based on a new radius estimate of R Ã ¼ 1:12 R for the parent star. Our theoretical predictions for the radius of HD 209458b are R pl ¼ 1:05R J and 1.09R J for models with and without cores. HD 209458b is therefore the only transiting planet whose radius does not agree well with our theoretical models. We argue that tidal heating stemming from dynamical interaction with a second planet is currently the most viable explanation for its inflated size. Subject headingg s: planetary systems -planets and satellites: general -stars: individual (HD 209458, TrES-1)
TIC 257060897b: An inflated, low-density, hot-Jupiter transiting a rapidly evolving subgiant star
Monthly Notices of the Royal Astronomical Society, 2021
We report the discovery of a new transiting exoplanet orbiting the star TIC 257060897 and detected using TESS full frame images. We acquired HARPS-N time-series spectroscopic data, and ground-based photometric follow-up observations from which we confirm the planetary nature of the transiting body. For the host star we determined: Teff = (6128 ± 57) K, log g = (4.2 ± 0.1), and [Fe/H] = (+ 0.20 ± 0.04). The host is an intermediate age (∼3.5 Gyr), metal-rich, subgiant star with M⋆ = (1.32 ± 0.04) M⊙ and R⋆ = (1.82 ± 0.05) R⊙. The transiting body is a giant planet with a mass mp =(0.67 ± 0.03) Mj, a radius rp = (1.49 ± 0.04) Rj yielding a density ρp = (0.25 ± 0.02) g cm−3 and revolving around its star every ∼3.66 d. TIC 257060897b is an extreme system having one of the smallest densities known so far. We argued that the inflation of the planet’s radius may be related to the fast increase of luminosity of its host star as it evolves outside the main sequence and that systems like ...
Astronomy & Astrophysics, 2005
Giant planets found orbiting close to their central stars, the so called “hot Jupiters”, are thought to have originally formed in the cooler outer regions of a protoplanetary disk and then to have migrated inward via tidal interactions with the nebula gas. We present the results of N-body simulations which examine the effect such gas giant planet migration has on the formation of terrestrial planets. The models incorporate a 0.5 Jupiter mass planet undergoing type II migration through an inner protoplanet-planetesimal disk, with gas drag included. Each model is initiated with the inner disk being at successively increased levels of maturity, so that it is undergoing either oligarchic or giant impact style growth as the gas giant migrates. In all cases, a large fraction of the disk mass survives the passage of the giant, either by accreting into massive terrestrial planets shepherded inward of the giant, or by being scattered into external orbits. Shepherding is favored in younger disks where there is strong dynamical friction from planetesimals and gas drag is more influential, whereas scattering dominates in more mature disks where dissipation is weaker. In each scenario, sufficient mass is scattered outward to provide for the eventual accretion of a set of terrestrial planets in external orbits, including within the system’s habitable zone. This scattering, however, significantly reduces the density of solid material, indicating that further accretion will occur over very long time scales. A particularly interesting result is the generation of massive, short period, terrestrial planets from compacted material pushed ahead of the giant. These planets are reminiscent of the short period Neptune-mass planets discovered recently, suggesting that such “hot Neptunes” could form locally as a by product of giant planet migration.
Comparison of current models for Hot Jupiters to the sample of transiting exoplanets
Arxiv preprint arXiv:1010.1032, 2010
A growing number (over 100!) of extra-solar planets (ESPs) have been discovered by transit photometry, and these systems are important because the transit strongly constrains their orbital inclination and allows accurate physical parameters for the planet to be derived, especially their radii. Their mass-radius relation allows us to probe their internal structure. In the present work we calculate Safronov numbers for the current sample of ESP and compare their masses and radii to current models with the goal of obtaining better constrains on their formation processess. Our calculation of Safronov numbers for the current TESP sample does show 2 classes, although about 20% lie above the formal Class I definition. These trends and recent results that argue against a useful distinction between Safronov classes are under further investigation. Mass-radius relations for the current sample of TESP are inconsistent with ESP models with very large core masses (≥ 100 M ⊕). Most TESP with radii near 1R J are consistent with models with no core mass or core masses of 10 M ⊕. The inflated planets, with radii ≥1.2 R J are not consistent with current ESP models, but may lie along the lower end of models for brown dwarfs. Although such models are nascent, it is important to establish trends for the current sample of ESP, which will further the understanding of their formation and evolution.
Formation of Giant Planets– An Attempt in Matching Observational Constraints
Space Science Reviews, 2005
We present models of giant planet formation, taking into account migration and disk viscous evolution. We show that migration can significantly reduce the formation timescale bringing it in good agreement with typical observed disk lifetimes. We then present a model that produces a planet whose current location, core mass and total mass are comparable with the one of Jupiter. For this model, we calculate the enrichments in volatiles and compare them with the one measured by the Galileo probe. We show that our models can reproduce both the measured atmosphere enrichments and the constraints derived by , if we assume the accretion of planetesimals with ices/rocks ratio equal to 4, and that a substantial amount of CO 2 was present in vapor phase in the solar nebula, in agreement with ISM measurements.
2021
We use a high-precision radial velocity survey of FGKM stars to study the conditional occurrence of two classes of planets: close-in small planets (0.023–1 au, 2–30 M⊕) and distant giant planets (0.23–10 au, 30–6000 M⊕). We find that 41 +15 −13% of systems with a close-in, small planet also host an outer giant, compared to 17.6 −1.9% for stars irrespective of small planet presence. This implies that small planet hosts may be enhanced in outer giant occurrence compared to all stars with 1.7σ significance. Conversely, we estimate that 42 −13% of cold giant hosts also host an inner small planet, compared to 27.6 −4.8% of stars irrespective of cold giant presence. We also find that more massive and close-in giant planets are not associated with small inner planets. Specifically, our sample indicates that small planets are less likely to host outer giant companions more massive than approximately 120 M⊕ and within 0.3–3 au than to host less massive or more distant giant companions, with ...