The period-mass and period-radius distribution of exoplanets is known to exhibit a desert. Unlike the existence of very hot (P orb < 3 d) super-Earths and hot Jupiters, no planets are known between a super Earths and sub-Jupiters with as short orbital periods as a day or two. In this Letter, we show that the period boundary of this desert is dependent on stellar parameters (T eff , [M/H], log g in the order of significance), there is a conclusive dependence on the incident stellar irradiation, and a dependence on the stellar mass acting only on planets around T eff < 5600 K host stars. We found a significant lack of very inflated planets on closest orbits to the host star. There is no significant dependence on tidal forces currently acting on the planet, planet's surface gravity, or current filling factor of Roche lobe. These distributions are most compatible with the dominant role of photoevaporation in forming the desert.
Aims. WASP-33 is one of the few δ Sct stars with a known planetary companion. By analyzing the stellar oscillations, we search for possible star-planet interactions in the pattern of the pulsation. Methods. We made use of the Transit and Light Curve Modeller to solve the light curve from the Transiting Exoplanet Survey Satellite. We include gravity darkening in our analysis. Results. The stellar oscillation pattern of WASP-33 clearly shows signs of several tidally perturbed modes. We find that there are peaks in the frequency spectrum that are at or near the 3rd, 12th, and 25th orbital harmonics (forb ∼ 0.82 d−1). Also, there is a prominent overabundance of pulsational frequencies rightward of the orbital harmonics, a characteristic of a tidally perturbed stellar pulsation, which is an outcome of star-planet interactions in the misaligned system. There are peaks in both the δ Sct and γ Dor ranges of the Fourier spectrum, implying that WASP-33 is a γ Dor – δ Sct hybrid pulsator. The transit light curves are best fitted by a gravity-darkened stellar model, and the planet parameters are consistent with earlier determinations.
Context. Correlated noise in exoplanet light curves, such as noise from stellar activity, convection noise, and instrumental noise, distorts the exoplanet transit light curves and leads to biases in the best-fit transit parameters. An optimal fitting algorithm can provide stability against the presence of correlated noises and lead to statistically consistent results, namely, the actual biases are usually within the error interval. This is not automatically satisfied by most of the algorithms in everyday use and the testing of the algorithms is necessary. Aims. In this paper, we describe a bootstrapping-like test to handle with the general case and we apply it to the wavelet-based Transit and Light Curve Modeller (TLCM) algorithm, testing it for the stability against the correlated noise. We compare and contrast the results with regard to the FITSH algorithm, which is based on an assumption of white noise. Methods. We simulated transit light curves with previously known parameters in the presence of a correlated noise model generated by an Autoregressive Integrated Moving Average (ARIMA) process. Then we solved the simulated observations and examined the resulting parameters and error intervals. Results. We have found that the assumption of FITSH, namely, that only white noise is present, has led to inconsistencies in the results: the distribution of best-fit parameters is then broader than the determined error intervals by a factor of 3–6. On the other hand, the wavelet-based TLCM algorithm handles the correlated noise properly, leading to both properly determined parameter and error intervals that are perfectly consistent with the actual biases.
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