Search

Atmospheric escape shapes the fate of exoplanets, with statistical evidence for transformative mass loss imprinted across the mass–radius–insolation distribution. Here, we present transit spectroscopy of the highly irradiated, low-gravity, inflated hot Saturn HAT-P-67 b. The Habitable Zone Planet Finder spectra show a detection of up to 10% absorption depth of the 10833 Å helium triplet. The 13.8 hr of on-sky integration time over 39 nights sample the entire planet orbit, uncovering excess helium absorption preceding the transit by up to 130 planetary radii in a large leading tail. This configuration can be understood as the escaping material overflowing its small Roche lobe and advecting most of the gas into the stellar—and not planetary—rest frame, consistent with the Doppler velocity structure seen in the helium line profiles. The prominent leading tail serves as direct evidence for dayside mass loss with a strong day-/nightside asymmetry. We see some transit-to-transit variability in the line profile, consistent with the interplay of stellar and planetary winds. We employ one-dimensional Parker wind models to estimate the mass-loss rate, finding values on the order of 2 × 10 ^13 g s ^−1 , with large uncertainties owing to the unknown X-ray and ultraviolet (XUV) flux of the F host star. The large mass loss in HAT-P-67 b represents a valuable example of an inflated hot Saturn, a class of planets recently identified to be rare, as their atmospheres are predicted to evaporate quickly. We contrast two physical mechanisms for runaway evaporation: ohmic dissipation and XUV irradiation, slightly favoring the latter.

Este artigo tem como objetivo investigar a dinâmica que determina quem possui o privilégio de discorrer sobre a matemática. Isso é realizado por meio da análise das experiências de duas jovens mulheres matriculadas em cursos de licenciatura em matemática, com a base na lente das epistemologias feministas. As protagonistas centrais deste estudo são estudantes desses cursos, que também se identificam como feministas, e cujas identidades e corpos desafiam as normas convencionais, com uma delas sendo negra e a outra sendo travesti. A abordagem do corpo é examinada sob a perspectiva das teorias de Butler e do Transfeminismo, as quais contribuem para a construção de corpos políticos. Este trabalho adota uma abordagem metodológica qualitativa feminista e utiliza entrevistas narrativas como a principal fonte de dados. A análise desses dados ressalta tanto as singularidades quanto as convergências presentes nas narrativas das entrevistadas. Os resultados evidenciam a importância da diversidade no contexto do aprendizado matemático, destacando a necessidade de incluir variadas vozes e perspectivas. Isso reforça a vitalidade da inclusão na educação matemática, permitindo que um leque amplo de visões participe.

One of the major challenges facing society, in order to avoid environmental degradation and the contamination of water and soil sources, is the adequate disposal of industrial and urban waste. The area of construction is also considered to be the most harmful to the environment, especially as regards the waste of natural resources and the gradual increase of waste. This study aims to analyze the waste recycling process for the manufacture of non-structural concrete, promoting the practice of waste recycling as a sustainable alternative for the disposal of the debris. In order to respond to the research objectives, the methodological choice was a bibliographical review of the integrative type. The study showed that waste recycling is a sustainable alternative for waste disposal, reducing the chances of deposition in clandestine sites, helping to relieve pressure on landfills and allowing reuse of previously discarded materials.