Banca de DEFESA: NATÁLIA PEREIRA DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : NATÁLIA PEREIRA DOS SANTOS
DATE: 03/08/2026
TIME: 14:30
LOCAL: remoto
TITLE:

Revisiting the Exoplanet Radius Distribution: The Impact of TESS Objects of Interest on the Separation Between Super-Earths and Sub-Neptunes

KEY WORDS:

exoplanets; radius valley; TESS; Kepler; planetary demographics; statistical methods

PAGES: 66
BIG AREA: Ciências Exatas e da Terra
AREA: Astronomia
SUMMARY:

The radius distribution of small exoplanets exhibits a characteristic structure known as the Radius Valley, associated with the separation between Super-Earths and Sub-Neptunes. In this work, we investigate the presence and detectability of this structure in the sample of TESS Objects of Interest (TOIs), focusing on planetary systems orbiting solar-type (FGK) stars. The analysis is conducted from an observational perspective, without applying completeness corrections, in order to assess the impact of instrumental biases on the morphology of the distributions. Initially, statistical goodness-of-fit tests (Kolmogorov-Smirnov and Anderson-Darling) and a multimodality test (Hartigan’s Dip Test) are applied to the planetary radius distribution. The results indicate that, although the TESS sample shows significant deviations from a log-uniform distribution, there is no statistically robust evidence of bimodality in the global distribution. Subsequently, the sample is analyzed as a function of host star spectral type, revealing indications that the structure of the valley becomes more pronounced in systems orbiting hotter stars. A comparison with the canonical Kepler sample, in which the Radius Valley was originally identified, highlights significant discrepancies between the distributions, primarily attributed to differences in observational sensitivity between the missions. While the Kepler sample exhibits a clear bimodal structure, the TESS sample is dominated by larger planets, hindering the identification of the valley. The construction of a combined sample (TESS + Kepler) allows the bimodal structure to be consistently recovered, demonstrating the complementary nature of the two surveys. Gaussian Mixture Model (GMM) modeling confirms the presence of two distinct planetary populations, with centers near ~1.3 and ~2.4 R, and a minimum in the distribution around ~1.7-1.8 R. When restricting the analysis to the range 1.0 <= R <= 3.0, the Radius Valley structure becomes more evident, indicating that its detectability is strongly influenced by population tails and observational selection effects. Overall, the results demonstrate that the Radius Valley is an intrinsic feature of the exoplanet population, whose observability critically depends on instrumental properties and sample completeness.

COMMITTEE MEMBERS:
Presidente - 1675216 - BRUNO LEONARDO CANTO MARTINS
Interno - 3060853 - IZAN DE CASTRO LEÃO
Externa à Instituição - SIMONE DAFLON DOS SANTOS - ON/MCT