A revista Cadernos de Astronomia é uma publicação semestral do Núcleo Cosmo-Ufes da Universidade Federal do Espírito Santo e que conta também com recursos humanos do Centro Brasileiro de Pesquisas Físicas e da Universidade Federal de Ouro Preto (vide o Corpo Editorial). Propõe-se a publicar artigos destinados à divulgação científica, história da ciência, ensino e pesquisa em astronomia e áreas correlatas. O objetivo é tornar acessível a um amplo público, que inclui estudantes secundários, graduandos e simpatizantes da área, o conhecimento científico relacionado à astronomia, cosmologia e gravitação. Possuindo acesso totalmente gratuito, cada número dedica uma seção inteira a um tema específico, onde especialistas nacionais e internacionais discutem em detalhes aspectos qualitativos e quantitativos do tópico em questão. A partir de 2023 os números semestrais dos CdA serão publicados nos meses de Março e Setembro. Cada um desses números possuem datas limite para receber submissões: Números publicados em Março - Submissões feitas até 10 de Janeiro; Números publicados em Setembro - Submissões feitas até 1º de Julho. Submissões recebidas após as datas limite acima não terão garantias de que, uma vez aceitas para publicação, façam parte do próximo número. Não sendo publicadas no próximo número, elas são automaticamente programadas para publicação no número subsequente a ser lançado.
Estimation of the photometric redshift of galaxies using artificial neural networks
This work was presented at the event "The Astro-Scientists: III Brazilian Meeting of Girls and Women in Astrophysics, Cosmology and Gravitation", held between March 31 and April 4, 2025.
Copyright (c) 2026 Sofia Garcia Telles Brito, Flávia Sobreira https://creativecommons.org/licenses/by/4.0
Environmental Mapping of Post-Starburst Galaxies
Summary of the poster presented in the third edition of the As Astrocientistas event, held between March 31st and April 4th, 2025.
Copyright (c) 2026 Rafaela Conz da Costa, Sandro Barboza Rembold https://creativecommons.org/licenses/by/4.0
Considerations on the impact of experiments and computational simulations with gravitational waves on the advancement of physics: the context of LIGO
The direct detection of gravitational waves represents one of the most important achievements of contemporary physics, opening a new window for observing the Universe. This work presents a report of a personal experience related to the scientific impact of gravitational-wave experiments regarding the experimental practice acquired through activities related to the Laser Interferometer Gravitational-Wave Observatory (LIGO) during a scientific exchange at the University of California, Riverside (UCR). As well, the computational simulation practice associated with the master’s research project of one of the authors is presented. Various experimental activities are described, like those involving standard LIGO cleaning protocols, the assembly and sealing of a vacuum chamber for preliminary tests, studies on heat absorption using spherical mirror configurations, and materials analysis. Based on the experience acquired, the authors reflect that matching experimental practice and computational simulation is valuable to help understand instrumental limitations, mitigating noise sources, and improving devices applied to gravitational-wave detection.
Copyright (c) 2026 Pamella Aline de Almeida, Nadja Simão Magalhães https://creativecommons.org/licenses/by/4.0
The Process of Investigating Planetary Transits in Photometric Light Curves from TESS
In exoplanetary astronomy, the transit method, based on the analysis of variations in stellar brightness due to the passage of the planet in front of its host star and recorded in light curves, is one of the main techniques for detecting planets outside the Solar System, responsible for most of the current discoveries. In this work, we use data obtained by the Transiting Exoplanet Survey Satellite (TESS) and study the use of a methodology for the processing, detection, and validation of transit signals in TESS photometric data, involving the adaptation of codes, the implementation of analysis pipelines, and the verification of candidates based on astrophysical criteria, with a view to identifying new exoplanets.
Copyright (c) 2026 Mariana S. Bittencourt, Clécio R. Bom, Stela Ishitani Silva https://creativecommons.org/licenses/by/4.0
Non-Parametric Reconstructions of Cosmic Curvature
Work presented at the event As Astrocientistas: III Encontro Brasileiro de Meninas e Mulheres da Astrofísica, Cosmologia e Gravitação, held between March 31 and April 4, 2025.
Copyright (c) 2026 Mariana L. S. Dias, Carlos A. P. Bengaly, Antônio F. B. da Cunha, Rodrigo S. Gonçalves, Jonathan Morais https://creativecommons.org/licenses/by/4.0
Black Strings and String Clouds Embedded in Anisotropic Quintessence: Solutions for Scalar Particles and Implication
In this work, we show that the radial solutions of the Klein-Gordon equation in an AdS spacetime composed of a black string, surrounded by both a matter distribution analogous to a string cloud and an anisotropic quintessence fluid, exhibit the occurrence of so-called dark phases, which are induced by the presence of the quintessential fluid. These dark phases are possible quantum observables for spin−0 particles located near the black string’s event horizon.
Copyright (c) 2026 Maria de Lourdes Deglmann https://creativecommons.org/licenses/by/4.0
We investigate the circumnuclear stellar populations of 12 Seyfert 2 galaxies selected from the Swift-BAT AGN Spectroscopic Survey based on their ultra-hard X-ray luminosity (14–195 keV). Using MUSE/VLT integral field spectroscopy and spectral synthesis, we spatially characterize the stellar populations in the central regions of the galaxies. Preliminary results indicate signatures of central stellar rejuvenation, with significant contributions from young and intermediate-age populations and the presence of radial metallicity gradients. Moderate correlations between stellar properties and AGN activity indicators suggest that both gas recycled by evolved stars and gas associated with recent star formation may contribute to supermassive black hole fueling. Given the exploratory nature of the sample, these results should be regarded as preliminary.
Copyright (c) 2026 Lais Nery Marinho, Rogério Riffel https://creativecommons.org/licenses/by/4.0
Work presented at ’The Astro-scientists: III Brazilian Meeting of Girls and Women in Astrophysics, Cosmology, and Gravitation,’ held between March 31 and April 4, 2025.
Copyright (c) 2026 Jhonny A. A. Ruiz, Alesandro Ferreira https://creativecommons.org/licenses/by/4.0
Acoustic barionic scale in $z_{eff} = 0,166$ with blue galaxies from SDSS
Work presented at the event As Astrocientistas: III Encontro Brasiliero de Meninas e Mulheres da Astrofísica, Cosmologia e Gravitação, held between March 31 and April 4, 2025.
Copyright (c) 2026 Hanna Lima, Rafael da Costa Nunes, Felipe Avila, Edilson Carvalho, Armando Bernui https://creativecommons.org/licenses/by/4.0
Non-linear effects: a new window for the primordial universe
Understanding the primordial universe is fundamental to connecting high-energy physics, observational cosmology, and the formation of cosmic structures. This article discusses the stochastic formalism applied to inflation and alternative collapse scenarios, highlighting its ability to access non-linear effects in the primordial density distribution. Applications to primordial black holes (PBHs), including strongly non-Gaussian curvaton scenarios, and to stochastic collapse models are presented, together with conceptual limitations and open questions.
Copyright (c) 2026 Tays Miranda https://creativecommons.org/licenses/by/4.0
A New perspective about the Hubble Constant
A constante de Hubble ($H_0$) é um parâmetro fundamental da cosmologia que descreve a velocidade com que o Universo está se expandindo atualmente, sendo este essencial para a definição da dinâmica cósmica. Contudo, os valores obtidos para $H_0$ apresentam uma crescente discrepância quando medidos por diferentes métodos observacionais, fenômeno conhecido na cosmologia como tensão em $H_0$ e sendo esse um dos desafios mais notáveis da cosmologia moderna, pois sugere que algo pode estar faltando em nosso entendimento atual do Universo ou dos métodos de medição. Este trabalho traz uma análise sobre a relevância da utilização de ondas gravitacionais na mensuração do valor da constante de Hubble, dado que sua recente detecção com contrapartida eletromagnética oferece uma nova ferramenta de medição, o que torna apropriado a mesma diante do atual panorama da tensão de $H_0$. Assim, o estudo explora o histórico e o arcabouço matemático relacionados ao tema, sempre com base em fontes já publicadas na literatura científica. A conclusão destaca que a medição da constante de Hubble por meio de ondas gravitacionais resultou em um valor de $70.0^{+12.0}_{-8.0} km/s/Mpc$. Embora esse resultado ainda tenha uma margem de incerteza considerável, ele mostra um potencial promissor para refinar e talvez solucionar a tensão existente em torno do valor da constante de Hubble, contribuindo assim para um melhor entendimento da expansão do Universo.
Copyright (c) 2026 Ranna Santana Pereira, Fernando Marques de Oliveira Moucherek https://creativecommons.org/licenses/by/4.0
Neural Network to interpret neutrino's signal from supernovae gravitational collapse
Massive stars end their life cycles when their inert core collapses and a protoneutron star (PNS) is born, often followed up by a supernova explosion. If such supernova were to occur in the Milky Way or a nearby galaxy, thousands to millions of neutrinos would be detected on laboratories on Earth. In this work we use a Long short-term memory (LSTM) neural newtwork to infer the gravitational mass of a PNS from the neutrinos it emits in the first two seconds after its formation. Neutrino data was obtained from spherically symmetric (1D) simulations of core-collapse supernovae of 18 progenitor stars employing two equations of state as well as two heating factors to emulate multidimensional effects in 1D simulations. We tested our LSTM network in data from core-collapse simulations of 49 stars not used in the training and showed that, in 18 cases, the neural network is able to reproduce the gravitational mass evolution of the PNS with only small deviations (R2 ≳ 0.80). We discuss how the neural network can be improved and the steps still needed so that it can be used to analyze future neutrino detections. To the best of our knowledge, this is the first work of its kind and will be useful as a parameterization of future works.
Copyright (c) 2026 Isadora da Silva Espíndola, André da Silva Schneider https://creativecommons.org/licenses/by/4.0
The Dark Sectos of the Universe in a Neutron Star Environment
In this work, we present some results from a series of studies investigating the effects of incorporating a dark-sector component into the structure of neutron stars. In particular, we examine how dark matter and dark energy fluids can alter the macroscopic properties of these compact objects. Two main scenarios are considered: the coexistence of three fluids coupled solely through gravity and the presence of interactions among them. We find that the impact of the dark-energy component on stellar structure depends on the equation-of-state parameter (ω), potentially leading to configurations with larger radii and higher maximum masses, whereas values of ω < −1 tend to weaken the hydrostatic support against gravitational collapse. More generally, larger relative fractions of the dark sector result in smaller stellar masses and radii due to their limited contribution to the total pressure. Across all scenarios considered, only specific parameter ranges were found to be consistent with current observational constraints, with the requirement of supporting maximum masses of at least (2 M⊙) providing the most stringent constraint.
Copyright (c) 2026 Loreany Ferreira de Araújo, José Ademir Sales de Lima, Germán Lugones https://creativecommons.org/licenses/by/4.0
Probing darking energy through gass mass fraction
We explore the possibility of breaking the dark degeneracy by using measurements of the gas mass fraction observed in massive and relaxed galaxy clusters. This data is particularly interesting for this purpose because it isolates the matter contribution, possibly allowing the degeneracy breaking. We study the particular case of the wCDM model with its interactive counterpart. We compare the results obtained from both descriptions with a non-parametric analysis obtained through Gaussian Process. Even though the degeneracy may be broken from the theoretical point of view, we find that current gas mass fraction data seems to be insufficient for a final conclusion about which approach is favored, even when combined with SNIa, BAO and CMB.
Copyright (c) 2026 Dinorah Barbosa, Rodrigo von Marttens, Javier Gonzalez, Jailson Alcaniz https://creativecommons.org/licenses/by/4.0
Investigating the Dark Sector with New Liht and HiddenParticles
Despite its success, the Standard Model (SM) of particle physics remains incomplete, with the absence of a dark matter (DM) candidate being one of its primary gaps. The lack of evidence for new heavy particles has driven interest toward light, feebly interacting DM candidates, whose thermal production in the early Universe requires a portal mediator. In this work, we propose a model where a vector mediator, originating from a U(1)Q gauge symmetry, connects the visible sector to inelastic dark matter (iDM) candidates. Unlike the standard dark photon scenario, in which SM fermions do not carry direct charges under the new symmetry, we explore Q charges defined by combinations of baryonic and leptonic numbers. We demonstrate that this framework can alter the relic abundance calculation and the experimental phenomenology. Consequently, such models can unlock new windows in the parameter space, expanding the possibilities for DM discovery beyond the constraints of the conventional model.
Copyright (c) 2026 Ana Luisa Foguel https://creativecommons.org/licenses/by/4.0
Copyright (c) 2026 Carla Rodrigues Almeida, Igor de O. C. Pedreira, Laura de Carvalho, Paola C. M. Delgado, Tays Miranda https://creativecommons.org/licenses/by/4.0
A Constrained Universe: reflections on women in astrophysics, cosmology, and gravitation
The history of women in science is marked by institutional restrictions that constricted their practices and hid their achievements. Even within this constrained universe, women were responsible for major scientific contributions; many of these remain partially or completely erased. In this essay, we will reflect on the role of gender in science through the works of Margaret Rossiter and Sandra Harding, two pioneers in gender studies who extended our comprehension about scientific practices. The discussion will be supported by historical examples of women researchers on the fields of astrophysics, cosmology, and gravitation.
Divulgação Científica, Ciência e Sociedade
Copyright (c) 2026 Carla Rodrigues Almeida https://creativecommons.org/licenses/by/4.0
The rebirth of general relativity: theses and historiographical perspectives
In this article, we discuss the thesis, common among physicists and historians, that, after three decades of stagnation, there was a “renaissance” of interest in general relativity in the 1950s and 1960s. We present two versions of this thesis: one places the shift in the 1950s, following the first conferences dedicated to general relativity, and the other identifies the shift in the 1960s, due to advancements in astrophysics. We review the main arguments supporting this thesis by physicists and historians, recall some of the criticisms it has received, and analyze the key historical evidence that emerges in this historiographical debate. Finally, we reflect on the validity of this thesis and on the current challenges in research on the history of general relativity.
Copyright (c) 2025 Juliana Correia Ferreira, Juliana Youssef, Thiago Hartz https://creativecommons.org/licenses/by/4.0
From gravity to water: analyzing climate change in Brazil with computational methods
Predicting droughts and floods in climatically dynamic regions requires rigorous analyses that integrate both spatial and temporal information. This study leverages gravitational data from the GRACE missions to examine hydrological variability in Brazil, an area of strategic importance due to its extensive river network and high sensitivity to global climate phenomena such as El Niño and the Pacific Decadal Oscillation. By adopting a computational framework that includes Singular Value Decomposition (SVD), CFAR (peak detection), and DBSCAN (spatial clustering), key variability patterns are identified and highlight regions with elevated hydrological vulnerability, notably Manaus, Mato Grosso, and Minas Gerais.
Copyright (c) 2025 Fabian Trigo https://creativecommons.org/licenses/by/4.0
Official monitoring of Brazil's native vegetation using satellite images: the BiomasBR program and the Prodes, Deter and TerraClass systems
The Brazilian government has three official satellite monitoring systems for monitoring native vegetation loss in its six biomes, designed and executed by the National Institute for Space Research, through the Brazilian Biomes Monitoring Program (BiomasBR): 1) Prodes - Annual Monitoring of Native Vegetation Suppression; 2) Deter - Daily Monitoring of Suppression and Degradation of Native Vegetation; and 3) TerraClass - Systematic Monitoring of Land Cover and Use. This article presents the main characteristics of each of these systems, the most recent results of Brazilian native vegetation monitoring, the main public policies based on BiomasBR, and the role of the program as a tool for achieving goals within international climate agreements.
João Felipe Sobrinho Kneipp Cerqueira Pinto
Copyright (c) 2025 Cláudio Aparecido de Almeida, Letícia Palazzi Perez, Mariane Souza Reis, Vagner Luis Camilotti , Cassiano Gustavo Messias, Erison Carlos dos Santos Monteiro, Taise Farias Pinheiro, João Felipe Sobrinho Kneipp Cerqueira Pinto, Luciana de Souza Soler, Lubia Vinhas, Luis Eduardo Pinheiro Maurano, Marcos Adami, Tatiana Mora Kuplich, Gustavo F. Balué Arcoverde, Igor da Silva Narvaes da Silva Narvaes, Silvana Amaral https://creativecommons.org/licenses/by/4.0
Climate Change and the Challenges Faced by the Amazonia
The Amazon, one of the most biodiverse biomes on the planet, plays a crucial role in global climate regulation and the hydrological cycle of South America. However, climate change and the intensification of human activities, such as deforestation and wildfires, have significantly impacted the region’s ecological stability. This article analyzes the effects of land-use changes on the Amazonian climate, emphasizing the relationship between forest degradation, greenhouse gas emissions, and alterations in precipitation patterns. It also discusses the impacts of atmospheric pollution, including locally and transcontinentally sourced aerosols, which affect the radiative balance and rainfall formation. Given this scenario, the need for strict environmental policies and international cooperation is reinforced to mitigate the effects of climate change and preserve the biome’s resilience. The upcoming COP 2025 in Belém do Pará is highlighted as a strategic opportunity to strengthen global commitments to forest conservation and environmental impact mitigation.
Copyright (c) 2025 Marco Aurélio de Menezes Franco https://creativecommons.org/licenses/by/4.0
The Production of ignorance about science: an analysis of the relationship between propaganda, the climate emergency and information ethics
Despite an apparent consensus on the strategic value of science for society and the material gains that the development of research and technologies brings to industry, culture and power relations, there is an important debate about the influence of external political and economic values on scientific knowledge. Using the conceptual perspective of agnotology, this article analyzes how propaganda campaigns use the information ethics of digital platforms to produce and disseminate doubt and ignorance about scientific knowledge of anthropogenic climate change and its spokespeople. Based on a literature review, we reinforce the warning of astrophysicists, geologists, sociologists and many other scientists about how the idea of a “neutral science” weakens the community and fuels denialism. We observe the main strategies and discourses that combat the consensus on the climate emergency and its relationship with an unsustainable economic model of exploitation of the planet’s resources, pointing out the responsibilities of the oil industry, agribusiness and big tech in this scenario.
Copyright (c) 2025 Carlos Eduardo Barros https://creativecommons.org/licenses/by/4.0
The historical supernovae, recorded by different observers around the globe for many centuries, may have also been depicted as rock art by Indigenous peoples of the Americas. There are suggestions of the association of petroglyphs and rupestrian art in the northern hemisphere with some of these events. This work aims to present and discuss whether a set of petroglyphs located in the states of Paraíba and Rio Grande do Norte may represent these historical supernovae. Using Stellarium software, the sky patterns at the time of each supernova explosion were simulated and then compared to the figures found. Considering the well-established cultural practices of the Tarairiú peoples, we identified suggestive correspondences between the figures and the supernovae of 185, 1054, and 1572, although the start of a definitive confirmation depends on dating analysis not yet available.
Copyright (c) 2025 Jorge Ernesto Horvath, Bianca Bulhões Martins, Felipe Felipe Sérvulo Maciel Costa, Luiz Carlos Jafelice https://creativecommons.org/licenses/by/4.0
Human development, which began around 300,000 years ago, has always occurred in parallel with natural climate variations. However, since the Industrial Revolution, human action has intensified the greenhouse effect, raising the average global temperature and altering weather patterns, resulting in severe impacts such as rising temperatures, changes in precipitation patterns and an increase in the frequency of severe weather events such as storms, tornadoes and hurricanes. This article explores the main current climate changes and how they are monitored through the analysis of historical data. In addition, it presents projections from climate models that allow us to anticipate future scenarios, including rising temperatures and changes in precipitation patterns, especially in South America. Finally, the text highlights the importance of concrete actions to mitigate greenhouse gas emissions, responsible for current climate change, using technologies already available. We conclude that, in order to face the climate emergency, it is essential to integrate Brazil’s human and natural resources, combined with scientific knowledge, in order to implement effective solutions to reduce impacts and protect the most vulnerable populations.
Copyright (c) 2025 Amanda Rehbein, Tercio Ambrizzi https://creativecommons.org/licenses/by/4.0
The mean life of CO2 in the Earth's atmosphere and the temperature increase over the 2050 horizon
In this work a toy model is presented describing the evolution of the CO2 level in the Earth’s atmosphere. Using present data on the CO2 emission resulting from the human activity and carbon stockage by mechanisms acting in the biosphere, the average lifetime of CO2 in the atmosphere was estimated to be 120 years. If the emission rate behavior observed in the last decades is maintained, our model predicts around 2050 a CO2 concentration of 513 ppm and a temperature increase of +2,6°C above the limit fixed by the Paris agreement.
Copyright (c) 2025 J. A. F. Pacheco https://creativecommons.org/licenses/by/4.0
The Antarctic Climate and the Four Decades of Research in the Brazilian Antarctic Program
Antarctica plays a key role in the planet’s climate dynamics. Its characteristic cold climate is responsible for maintaining temperatures, global climate modulation, sustaining ecosystems and ice-dependent biodiversity. Likewise, the region is significantly impacted by global climate change. Over the past few decades, the Brazilian Antarctic Program has been making efforts to study the region, with several modules and facilities used to collect climatic, atmospheric, and biological data, among others. This paper characterizes the Antarctic climate, its importance in the global context, the impacts of climate change on Antarctica, and the efforts of the Brazilian Antarctic Program to study the polar climate.
Copyright (c) 2025 Dafne Anjos, Cesar Amaral, Anna Donato, Rodrigo Goldenberg-Barbosa, Letícia Eller https://creativecommons.org/licenses/by/4.0
Cosmic Rays and their Connections to Earth's Climate
There is now a consensus among scientists that human contribution to greenhouse gas emissions has caused a significant increase in global temperature over the last century, with simulations indicating an increase of around 5.0°C by 2100. In these models, cloud dynamics contribute the greatest uncertainties. Although the process is based on a relatively well-known chain, from aerosols evolving into condensation nuclei to macroscopic clouds, the role of ionic induction promoted by cosmic rays as a possible intensifier of nucleating processes in the atmosphere remains inconclusive. Recent research carried out at the particle physics laboratory, CLOUD/CERN, despite the difficult task of emulating the atmosphere in the laboratory, has yielded results that motivate its study in a real system, as in the Brazilian project CRE4AT (Cosmic Ray Experiment for Atmosphere).
Copyright (c) 2025 André Massafferri Rodrigues https://creativecommons.org/licenses/by/4.0
It includes the editorial information for this edition, the Letter to the Reader, and the Table of Contents.
Copyright (c) 2026 Os Editores https://creativecommons.org/licenses/by/4.0
Dark energy and the challenges to the standard cosmological model
Observational evidence that the Universe is undergoing accelerated expansion represents one of the main challenges of modern cosmology, usually attributed to the presence of a dominant component known as dark energy. The standard cosmological model, ΛCDM, provides a consistent description of a wide range of observations, but faces significant difficulties from both a theoretical and observational standpoint. In this article, we present a review of the ΛCDM model, discussing its theoretical foundation and the main observational tests that support its validity. We emphasize recent observational strains, such as those associated with the Hubble constant (H0) and the amplitude of matter fluctuations (S8), as well as recent results from the DESI survey that suggest possible deviations from the standard model. We also discuss the implications of these strains and possible extensions of the model, highlighting the role of scenarios with dynamic dark energy. This overview seeks to provide an updated view of the challenges faced by contemporary cosmology and the prospects for understanding cosmic acceleration.
Copyright (c) 2026 Rodrigo Von Marttens, Jailson Alcaniz, Saulo Carneiro https://creativecommons.org/licenses/by/4.0
Cosmological considerations on the general theory of relativity.
We present the translation of the article published by Albert Einstein in 1917. In it, he introduces, for the first time, a cosmological constant, a term that today plays a very important role in the standard model of cosmology. Some introductory comments are presented, followed by the Portuguese version of the text originally written in German.
Copyright (c) 2026 Albert Einstein; Júlio C. Fabris (trad.), Oliver F. Piattella (trad.) https://creativecommons.org/licenses/by/4.0