PyIRD is a Python-based pipeline for reducing spectroscopic data obtained with IRD (InfraRed Doppler; Kotani et al. (2018)) and REACH (Rigorous Exoplanetary Atmosphere Characterization with High dispersion coronagraphy; Kotani et al. (2020)) on the Subaru Telescope. It is designed to process raw images into one-dimensional spectra in a semi-automatic manner. Unlike traditional methods, it does not rely on IRAF (Tody, 1986; 1993), a software used for astronomical data reduction. This approach simplifies the workflow while maintaining efficiency and accuracy. Additionally, the pipeline includes an updated method for removing readout noise patterns from raw images, enabling efficient extraction of spectra even for faint targets such as brown dwarfs. The code is open source and available at https://github.com/prvjapan/pyird .
Jens Kammerer, Sydney Vach, Sylvestre Lacour
et al.
Direct observations of exoplanets probe the demographics and atmospheric composition of young self-luminous companions, yielding insight into their formation and early evolution history. In the near future, Gaia will reveal hundreds of nearby young exoplanets amenable to direct follow-up observations. Long-baseline interferometry with current and future facilities is best capable of exploiting this unique synergy which is poised to deliver a statistical sample of benchmark planets with precise dynamical masses and in-depth atmospheric characterization. This will enable tackling the longstanding question of how giant planets form from multiple angles simultaneously, shining light on the complex physical processes underlying planet formation.
Este texto foi extraído da palestra realizada no dia 10 de Fevereiro de 2023 pela autora na segunda edição do evento As Astrocientistas: Encontro Brasileiro de Meninas e Mulheres da Astrofísica, Cosmologia e Gravitação.
Solar-type stars form with a wide range of rotation rates. A wide range persists until a stellar age of 0.6 Gyr, after which solar-type stars exhibit Skumanich spin-down. Rotational evolution models incorporating polytropic stellar winds struggle to simultaneously reproduce these two regimes, namely the initially wide range and the Skumanich spin-down without imposing an a-priori cap on the wind mass-loss rate. We show that a three-dimensional wind model driven by Alfvén waves and observational data yields wind torques that agree with the observed age distribution of rotation rates. In our models of the Sun and twenty-seven open cluster stars aged from 0.04 to 0.6 Gyr that have observationally derived surface magnetic maps and rotation rates, we find evidence of exponential spin-down in young stars that are rapid rotators and Skumanich spin-down for slow rotators. The two spin-down regimes emerge naturally from our data-driven models. Our modelling suggests that the observed age distribution of stellar rotation rates arises as a consequence of magnetic field strength saturation in rapid rotators.
AbstractCharacterising the mechanical properties of flowing microcapsules is important from both fundamental and applied points of view. In the present study, we develop a novel multilayer perceptron (MLP)-based machine learning (ML) approach, for real-time simultaneous predictions of the membrane mechanical law type, shear and area-dilatation moduli of microcapsules, from their camera-recorded steady profiles in tube flow. By MLP, we mean a neural network where many perceptrons are organised into layers. A perceptron is a basic element that conducts input–output mapping operation. We test the performance of the present approach using both simulation and experimental data. We find that with a reasonably high prediction accuracy, our method can reach an unprecedented low prediction latency of less than 1 millisecond on a personal computer. That is the overall computational time, without using parallel computing, from a single experimental image to multiple capsule mechanical parameters. It is faster than a recently proposed convolutional neural network-based approach by two orders of magnitude, for it only deals with the one-dimensional capsule boundary instead of the entire two-dimensional capsule image. Our new approach may serve as the foundation of a promising tool for real-time mechanical characterisation and online active sorting of deformable microcapsules and biological cells in microfluidic devices.
We propose a self-consistent explanation of Rieger-type periodicities, the Schwabe cycle, and the Suess-de Vries cycle of the solar dynamo in terms of resonances of various wave phenomena with gravitational forces exerted by the orbiting planets. Starting on the high-frequency side, we show that the two-planet spring tides of Venus, Earth and Jupiter are able to excite magneto-Rossby waves which can be linked with typical Rieger-type periods. We argue then that the 11.07-year beat period of those magneto-Rossby waves synchronizes an underlying conventional $α-Ω$-dynamo, by periodically changing either the field storage capacity in the tachocline or some portion of the $α$-effect therein. We also strengthen the argument that the Suess-de Vries cycle appears as an 193-year beat period between the 22.14-year Hale cycle and a spin-orbit coupling effect related with the 19.86-year rosette-like motion of the Sun around the barycenter.
How do the characteristics of starspots influence the triggering of stellar flares? Here we investigate the activity of two K-type stars, similar in every way from mass to rotation periods and planetary systems. Both stars exhibit about a hundred spots, however, Kepler-411 produced 65 superflares, while Kepler-210 presented none. The spots of both stars were characterized using the planetary transit mapping technique, which yields the intensity, temperature, and radius of starspots. The average radius was $(17\pm7) \times 10^3$ km and $(58 \pm 23) \times 10^3$ km, while the intensity ratio with respect to the photosphere was $(0.35\pm0.24)$ $I_{c}$ and $(0.64\pm0.15)$ $I_{c}$, and the temperature was $(3800 \pm 700)$ K and $(4180 \pm 240)$ K for spots of Kepler-411 and Kepler-210, respectively. Therefore, spots on the star with no superflares, Kepler-210, are mostly larger, less dark, and warmer than those on the flaring star, Kepler-411. This may indicate magnetic fields with smaller magnitude and complexity of the spots on Kepler-210 when compared to those on Kepler-411. Thus, starspot area appears not to be the main culprit of superflares triggering. Perhaps the magnetic complexity of active regions is more important.
The presence of cubic PuH2 and PuH3, the products of hydrogen corrosion of Pu, during long-term storage is of concern because of the materials’ pyrophoricity and ability to catalyse the oxidation reaction of Pu to form PuO2. Here, we modelled cubic PuH2 and PuH3 using Density Functional Theory (DFT) and assessed the performance of the PBEsol+U+SOC (0 ≤ U ≤ 7 eV) including van der Waals dispersion using the Grimme D3 method and the hybrid HSE06sol+SOC. We investigated the structural, magnetic and electronic properties of the cubic hydride phases. We considered spin–orbit coupling (SOC) and non-collinear magnetism to study ferromagnetic (FM), longitudinal and transverse antiferromagnetic (AFM) orders aligned in the <100>, <110> and <111> directions. The hybrid DFT confirmed that FM orders in the <110> and <111> directions were the most stable for cubic PuH2 and PuH3, respectively. For the standard DFT, the most stable magnetic order is dependent on the value of U used, with transitions in the magnetic order at higher U values (U > 5 eV) seen for both PuH2 and PuH3.
R. Astro, Konstantinus Denny Pareira Meke, Kristina Sara
et al.
This study aimed to analyze the knowledge and readiness of students in the application of Independent Learning-Independent Campus (MBKM) in the Study Program of Information Systems, Faculty of Information Technology, Flores University. This study applied a survey method with a descriptive approach. The data obtained from the population are 277 student respondents. The instrument used in this study was a questionnaire using SPADA DIKTI by the Ministry of Education, Culture, Research, and Technology (KEMDIKBUD RISTEK). Data that has been collected through questionnaires were analyzed using descriptive analysis. The results of this study indicated that students in the Study Program of Information Systems, Faculty of Information Technology, Flores University have sufficient knowledge and readiness and a positive response to the MBKM program. This shows that MBKM has a positive impact on the technical, learning process and evaluation of learning activities in higher education. Article History Received: 30-12-2021 Revised: 29-01-2022 Accepted: 14-02-2022 Published: 09-03-2022
Galáxias são alguns dos objetos astronômicos mais impressionantes conhecidos. São estruturas com com tamanhos de dezenas ou até centenas de milhares de anos-luz, contendo centenas de bilhões de estrelas, e imersas em um halo de matéria escura com trilhões de vezes a massa do Sol. Dadas as suas dimensões impressionantes, pode ser curioso pensar que uma galáxia apresenta um ciclo de vida. Mas sim, uma galáxia nasce, evolui e “morre”, embora o processo possa levar alguns bilhões de anos. Neste texto, vou descrever alguns dos processos que conhecemos sobre a evolução de galáxias, ou que ainda estamos tentando descobrir, e como os cientistas estão trabalhando para desvendar esses mistérios.
O Sol e as estrelas apresentam atividade magnética na forma de manchas escuras em sua superfície, além de produzirem explosões e ejeções de massa de suas atmosferas. As assinaturas de manchas escuras na superfície das estrelas podem ser modeladas a fim de caraterizar seus tamanhos e temperaturas. Estrelas jovens e anãs M produzem energéticas superexplosões, as quais podem impactar os planetas em órbitas, principalmente os que estiverem bem próximos da sua estrela hospedeira. O fluxo de radiação ultravioleta destas explosões pode ser prejudicial para possíveis organismos vivos na superfície de exoplanetas orbitando na zona habitável de estrelas ativas. Entretanto, uma atmosfera com ozônio poderia protegê-los, ou então um oceano. Os ventos estelares também afetam as atmosferas planetárias, podendo ser responsáveis pela sua erosão.
J. J. Chebly, J. D. Alvarado-Gómez, K. Poppenhaeger
Stars interact with their planets through gravitation, radiation, and magnetic fields. Although magnetic activity decreases with time, reducing associated high-energy (e.g., coronal XUV emission, flares), stellar winds persist throughout the entire evolution of the system. Their cumulative effect will be dominant for both the star and for possible orbiting exoplanets, affecting in this way the expected habitability conditions. However, observations of stellar winds in low-mass main sequence stars are limited, which motivates the usage of models as a pathway to explore how these winds look like and how they behave. Here we present the results from a grid of 3D state-of-the-art stellar wind models for cool stars (spectral types F to M). We explore the role played by the different stellar properties (mass, radius, rotation, magnetic field) on the characteristics of the resulting magnetized winds (mass and angular momentum losses, terminal speeds, wind topology) and isolate the most important dependencies between the parameters involved. These results will be used to establish scaling laws that will complement the lack of stellar wind observational constraints.
Accurate disk mass measurements are necessary to constrain disk evolution and the timescale of planet formation, but such measurements are difficult to make and are very dependent on assumptions. Here we look at the assumption that the disk is optically thin at radio wavelengths and the effect of this assumption on measurements of disk dust mass. We model the optical to radio spectral energy distributions (SEDs) of 41 protoplanetary disks located in the young (~1-3 Myr old) Lupus star-forming region, including 0.89 mm, 1.33 mm, and 3 mm flux densities when available. We measure disk dust masses that are ~1.5-6 times higher than when using the commonly adopted disk dust mass equation under the assumption of optically thin emission in the (sub-)millimeter. The cause of this discrepancy is that most disks are optically thick at millimeter wavelengths, even up to 3 mm, demonstrating that observations at longer wavelengths are needed to trace the fully optically thin emission of disks.
Regina Rudawska, Mária Hajduková, Tadeusz J. Jopek
et al.
Since 2007, the Meteor Data Center (MDC) has had two components: the Orbital database (OD) and the Shower database (SD). The orbital part is in charge of the efficient collection, checking, and dissemination of geocentric parameters and orbits of individual orbits. Is also acts as a central depository for meteoroid orbits obtained by different techniques: photographic, television, video, CCD and radar. The shower database collects the geocentric and orbital parameters of the meteor showers and meteoroids streams. It is not an archive of all information related to meteor showers, its primary task is to give unique names and codes to new meteor showers (streams). The SD acts in conjunction with the Working Group on Meteor Shower Nomenclature of International Astronomical Union (IAU) Commission F1, "Meteors, Meteorites, and Interplanetary Dust". In our paper, we give a concise description of the IAU MDC database, its origin, structure and, in particular, the current requirements for the introduction of new orbital and shower data.
Galáxias desempenharam e seguem desempenhando um relevante papel na determinação da matéria escura e suas propriedades. Apresentamos uma introdução sobre a dinâmica interna de galáxias, em particular sobre a rotação de galáxias de disco, e sobre como seus dados indicam a presença de matéria escura. Este texto é destinado a qualquer leitor interessado no assunto, ainda que sem experiência prévia em astrofísica.
Neste artigo são revistos os principais eventos que teriam ocorrido nas primeiras fases de evolução do universo, quando o plasma cósmico é opaco à radiação eletromagnética. Neste caso, a informação sobre tais eventos não pode provir de fótons mas somente de ondas gravitacionais, detetadas pela primeira vez em 2015. Serão revisitados os espectros do fundo de ondas gravitacionais gerados durante o período inflacionário e as transições de fase eletrofraca e quark-hádron. Além disso, são examinados os espectros do fundo de ondas gravitacionais gerados em cenários alternativos ao \textit{big bang}, sugeridos por teorias efetivas de campo.
PURPOSE In 2014 ASTRO's Accreditation Program for Excellence (APEx®) was created in response to the Target Safely campaign. APEx is a powerful tool to measure and drive quality improvement in radiation oncology practices. METHODS A task group from ASTRO's Practice Accreditation Committee was formed to provide an overview of the APEx accreditation program including analysis from specific program data.