The Sun, our host star, plays a fundamental role in astrophysics due to its vicinity. To understand the processes taking place in the outermost layers of the Sun, but also, indirectly, in its interior, we conduct high spectral and spatial resolution, high cadence observations of diagnostically important spectral lines. The intensity and the polarization of the electromagnetic radiation in the observed spectral lines are a result of the joint action of absorption, emission, and scattering processes, further altered by the Zeeman and Hanle effects. Spectropolarimetric inversions are the techniques devised for the inference of the physical parameters in the solar atmosphere through the interpretation of spectral line shapes and line polarization. This review aims to provide a pedagogical overview of the necessary radiative transfer formalism and cutting-edge techniques, and to help interested readers enter the field and use some of the concepts in their own research. The secondary aim is a critical assessment of the emerging directions for the development of spectropolarimetric inversions, namely, to discuss the friction between physical realism, numerical efficiency, and modeling of the instrumental effects.
We present two new radio-continuum images from the Australian Square Kilometre Array Pathfinder (ASKAP) POlarisation Sky Survey of the Universe's Magnetism (POSSUM) survey in the direction of the Small Magellanic Cloud (SMC). The two new source lists produced from these images contain 36,571 radio continuum sources observed at 944 MHz and 15,227 sources at 1367 MHz, with beam sizes of 14.''5x12.''2 and 8.''7x8.''2, respectively. We used the Aegean software to create these point source catalogues, and together with the previously published Meer-Karoo Array Telescope (MeerKAT) point source catalogue, we estimated spectral indices for the whole population of radio point sources in common. By cross-matching our ASKAP catalogues with the MeerKAT catalogue, we found 21,442 and 12,654 point sources in common for 944 MHz and 1367 MHz, respectively, within a 2'' region. This point source catalogue will help to further our knowledge of the SMC and highlights the power of the new generation of telescopes such as ASKAP in studying different galactic populations.
Coronal holes (CHs) play an important role in solar physics. They contribute to geomagnetic storms. The emission of charged particles into interplanetary space influences the space weather. CHs, being an important part of the solar activity, have a significant influence on Earth's climate. So, detection of CH regions is a significant task. Many attempts have already been made in this regard. In this work, we are proposing a new method for automatic detection of CH regions using a deep learning technique. We used Supervised Intensity Thresholding with Distance Transform Clustering and Connected Component Labeling (SITDTCCCL) to find out Regions of Interest (ROI) on 193 A & ring; images collected from the Solar Dynamics Observatory (SDO). The state-of-the-art deep learning method (YOLO v8) has shown excellent performance in detection of CH regions with scores of evaluation matrices such as F1 score 95%, Precision 97.1%, mAP50 98.1%, and True Positive Rate
This study explores a Kantowski-Sachs cosmological model within the framework of Modified gravity, utilizing an interacting field as the energy source. The interacting field comprises a linear combination of electromagnetic, massless scalar, and charged perfect fluid components. Our analysis encompasses four distinct scenarios: perfect fluid, disordered radiation, dust fluid, and dark energy. By establishing a relationship between metric potentials, we solved the field equations and investigated pressure and density profiles using the equation of state. A comprehensive examination of cosmological and dynamical parameters was also conducted.
The purpose of this study is to investigate the relation between binary asteroids and mean motion resonances (MMRs). For more than 700 asteroids from two catalogues, the Johnston Archive (Johnston 2024) and the Gaia DR3 VizieR list of binary candidates from Liberato et al. (2024), we applied a resonance identification algorithm, treating all planetary perturbations. Our results showed that the presence of binary asteroids in MMRs largely depends on their dynamical class. The highest percentage, more than 30%, is found in the Trans-Neptunian region where most of these objects have exhibited resonant librations longer than 10 Myr. For the main-belt asteroid pairs, this percentage is about 10-12%. Contrary to expectations, the more unstable region populated with NEOs, showed a higher percentage of resonant pairs (above 17%), but with temporal resonant captures. These results could indicate that the mean motion resonances, particularly the stronger ones, could play a role in the evolution and formation of binary systems. Finally, we highlight that in the present paper, 82 resonant binary asteroids are newly identified.
