Band 34, Heft 1

In this third article in a series, we investigate the need of spectra denoising for the derivation of stellar parameters. We have used two distinct datasets for this work. The first one contains spectra in the range of 4,450–5,400 Å at a resolution of 42,000, and the second in the range of 8,400–8,800 Å at a resolution of 11,500. We constructed two denoising techniques, an autoencoder, and a principal component analysis. Using random Gaussian noise added to synthetic spectra, we have trained a neural network to derive the stellar parameters T eff {T}_{{\rm{eff}}} , log g \log g , v e sin i {v}_{{\rm{e}}}\sin i , ξ t {\xi }_{{\rm{t}}} , and [M/H] of the denoised spectra. We find that, independently of the denoising technique, the accuracy values of stellar parameters do not improve once we denoise the synthetic spectra. This is true with and without applying data augmentation to the stellar parameters neural network.

This article presents X-ray emission characteristics of the brightest member of a G50 galaxy group NGC 5846 based on analysis of high resolution of 30 ks and 90 ks Chandra X-ray data. X-ray imaging analysis revealed the presence of 90 discrete X-ray point sources, spectral study of which depicted that the majority of them are LMXBs with a neutron star accretor. Among 90, only one source exhibits an X-ray luminosity greater than 1 0 39 erg s − 1 1{0}^{39}\hspace{0.33em}{\rm{erg}}\hspace{0.33em}{{\rm{s}}}^{-1} , exceeding the Eddington limit for a canonical mass of a neutron star and occupies a position in the hard region of the X-ray color–color plot. The cumulative X-ray luminosity function plot for all resolved XRBs exhibits a knee at L X = 6.6 × 1 0 38 erg s − 1 {L}_{X}=6.6\times \hspace{0.33em}1{0}^{38}\hspace{0.33em}{\rm{erg}}\hspace{0.33em}{{\rm{s}}}^{-1} , corresponding to the Eddington limit of 2.8 solar mass neutron star. The most dominant source of the observed X-ray luminosity of NGC 5846 happens to be the diffusely distributed plasma, making its contribution up to 85% of its total value, while the contribution from resolved and unresolved point sources is up to 15%. The surface brightness distribution of the X-ray emitting gas in this galaxy exhibit structures in the form of discontinuities due to the presence of a pair of cold fronts at ∼ 20 \sim 20 kpc. The presence of these cold fronts were confirmed in the azimuthally averaged surface brightness profile and sectorial temperature profiles and may have formed due to minor mergers. The larger values of emission line flux density ratio log([N II]H α \alpha ) and floor in the entropy profile of the plasma collectively point toward a nonthermal ionization source of gas heating like a low-level AGN activity.

This study investigated the ionospheric response to a moderate geomagnetic storm recorded on May 14, 2019, with a minimum disturbance storm time (Dst) index of − 70 -70 nT. Observations from three Global Positioning System (GPS) stations (RFHA, 29.6 ∘ {\text{29.6}}^{\circ } N; ARAR, 30.9 ∘ {\text{30.9}}^{\circ } N; TRIF, 31.6 ∘ {\text{31.6}}^{\circ } N) in Saudi Arabia’s Northern Borders Province were used to derive the vertical total electron content (VTEC), revealing a significant increase during the storm’s main phase. A comparative analysis of GPS-derived VTEC with the International Reference Ionosphere 2016 (IRI-2016) model showed that IRI-2016 tends to overestimate VTEC during quiet and disturbed geomagnetic conditions. Additionally, GPS-VTEC data were utilized to detect traveling ionospheric disturbances within 30 min, moving poleward across the Northern Arabian Peninsula throughout the storm. These findings highlight the impact of the geomagnetic activity on ionospheric dynamics and the effectiveness of the new GPS stations in monitoring ionospheric behavior over the Arabian Peninsula.

In this study, we investigate the hypothesis that γ-ray emissions from jetted active galactic nuclei (AGNs) are strongly beamed using the dominant relativistic beaming model of the samples of 532 blazars (281 flat-spectrum radio quasars [FSRQs] and 251 BL Lacertae objects [BL Lacs]) and 16 narrow line Seyfert 1 galaxies (NLSy1s). Our comparison of the distribution of the radio core-dominance ( R ) reveals that FSRQs exhibit the highest core dominance with a mean value of 1.32 ± 0.08, followed by BL Lacs at 1.21 ± 0.05, and NLSy1s at 0.93 ± 0.21. Our analysis indicates that over 80% (approximately 426) of our samples have log R > 0, with the values for FSRQs and BL Lacs extending by more than one magnitude. This suggests that γ-ray emissions in BL Lacs and FSRQs are significantly and relativistically boosted, while the effect is less pronounced in NLSy1s. Additionally, the data show that NLSy1s have the largest mean viewing angle compared to FSRQs and BL Lacs. This implies that at very small viewing angles, relativistic beaming and orientation effects are more significant in blazars than in NLSy1s. Further analysis reveals a moderate positive correlation (coefficient r ∼ 0.50) between the core-dominance parameter and both the γ-ray luminosity and redshift for the combined samples. These results are consistent with the relativistic beaming model and suggest that γ-ray emissions from blazars and NLSy1 galaxies are strongly beamed. This comprehensive analysis supports the notion that relativistic beaming plays a critical role in testing the hypothesis of γ-ray emissions of jetted AGNs. Thus, our findings contribute to a deeper understanding of the concept of relativistic beaming in different types of jetted AGNs, highlighting the importance of viewing angles and relativistic effects in interpreting γ-ray observations.

Over the past two decades, interstellar dust and cometary material have been found to include a significant content of organic and biogenic molecules. This possibly hints towards a genesis of life in cometary bodies, with comets acting as carriers of microbial life throughout the galaxy. We describe here a computational study of the role of radiogenic heating due to 26 {}^{26} Al in the thermal evolution of a cometary interior and thereby delineate zones with possible liquid water content. Thermal evolution calculations are carried out for comets possessing various radii, starting from an initial accretion phase to some 100 million years after the completion of accretion. Our computation shows that comets with radius 6 km and higher can have liquid water interior regions and hence can support zones where microbes can survive. Such microbial survival zones are traced out as regions where the temperature rises above the melting point of water ice and later remain below a sterilizing temperature. The active time available for possible microbial multiplication is also determined. Computations also show that survival zones are not generally found at the centres of comets but at varying radial distances from the centre, depending on the radius of the comet.

In this article, a number of smoothing methods were investigated to enhance the signal-to-noise (S/N) ratio of diverse methanol maser spectral data, encompassing variations in signal strength, multiplicity of peaks, and spectral complexity. The study aimed to improve the accuracy and reliability of astronomical measurements obtained with Irbene radio telescopes RT-16 and RT-32 at the Ventspils International Radio Astronomy Center. Comparing eleven different smoothing techniques, including moving average, Gaussian, Hanning, among others, the Savitzky–Golay smoothing method is identified as the optimal choice. The evaluation criteria included the preservation of spectral features, reduction of noise artifacts, and enhancement of S/N ratio metrics. The Savitzky–Golay method outperformed other techniques by effectively balancing noise reduction with the preservation of spectral details crucial for maser emission analysis.

The bulk planetary compositions are thought to be consistent with the chemical abundances of their host stars. The abundances of eight key rock-forming elements and the key planetary abundance ratios in G- and F-type main sequence stars located in the solar neighborhood within 50 pc were statistically analyzed. The averaged C/O, Mg/Si, and Fe/Si elemental ratios of the planetary systems play a crucial role in the chemical composition and mineralogy of a rocky planet's interior. We also investigated the variation of the calculated Ca/Si, Al/Si, Na/Si, and Fe/Si ratios in the samples of the examined stars utilizing the Ca, Al, Na, and Fe abundances from the catalog and then attempted to establish plausible occurrence trends of the analyzed abundance ratios for the rocky planet population at near-solar galactocentric distances. Considering these results, we provide simple predictions for the most likely bulk compositions of the potential rocky planets. We apply our results to compare them to the solar averaged abundance ratios, showing that the key elemental ratios for terrestrial planet composition in the Solar System are not typical among most of the studied stellar samples.

The interplay among emerging technologies, including artificial intelligence, and creative activities that involve engaging not only thought or the brain, but also the entire organism to produce a product, such as creating 3D models through cutting, pasting, and assembling, and then using those models to analyze natural phenomena, to verify and ultimately comprehend the relationship between the two, is a central theme of our time. This presentation showcases a few simple, albeit insufficient, examples to illustrate the importance of returning to activities that we can associate with the “ main-à-la patte ” or “ hands-on ” actions. The discussion of how to integrate new technologies into problem-solving and leverage their potential to enhance our understanding of the natural world, while ensuring that any formal or informal activity at this inflection point of human existence is “user-centered” in universal terms, is also explored.

Investigations of interstellar microscopic phenomena often are in need of a simple, standardized, yet flexible approach for macrophysical evolution of evolving molecular cloud cores. With the help of a 1D model, we provide analytical functions – polynomial equations – tracking gas and dust temperature, density, and column density in seven spherical collapsing prestellar cores in the mass range from 0.5 to 30  M ⊙ {{\rm{M}}}_{\odot } . Seven geometrical points were sampled along the radius of each core. The resulting data represent physical conditions in parcels in the early presolar nebula and other protostellar collapsing cores. The data are adapted as testbed for models focusing on chemistry or other complex processes.

As China’s only non-core K-12 science subject, astronomy education faces resource constraints. Beijing Planetarium (BJP), home to the Chinese Astronomical Society Popularization Committee, addresses this through tiered programs. The Secrets of Time and Space series uses exhibitions for upper primary students, while the 3D-Printed Astronomy Course integrates Science, Technology, Engineering, and Math (STEM) technology. The Astronomy Science Creative Workshop targets advanced learners with STEM foundations, fostering interdisciplinary skills. The Children Role-Playing Imperial Astronomers series leverages the Beijing Ancient Observatory to highlight ancient Chinese achievements. BJP’s international collaborations via Network for Astronomy School Education (NASE) adopt the 14 steps to the universe framework. Teaching modalities include offline Cosmic Youth Group parent–child programs and Cosmic Laboratory experiments, alongside online Celestial e-Classroom and Stellar Sisters Workshop . Nationwide initiatives like Mobile Planetarium , Teacher Training , and Astronomy Competition extend reach. Since 1957, BJP has been pivotal in astronomy education. The 2012 NASE partnership accelerated global integration. Future plans focus on expanding collaborations to bridge educational gaps and advance astronomy popularization.

Astronomy education in Indonesia faces considerable challenges due to its limited inclusion in the formal curriculum and a shortage of trained educators. The Network for Astronomy School Education (NASE) has played a crucial role in addressing these gaps by organizing structured training programs for teachers. This study evaluates the impact of NASE courses conducted between 2016 and 2024, highlighting their contributions to teacher training, student engagement, and the broader development of astronomy education in Indonesia. Through posttraining questionnaires, the study assesses improvements in teachers’ understanding of astronomy, pedagogical practices, and student interest. The increase in participants’ confidence and the successful integration of NASE materials into classroom instruction highlights the program’s effectiveness. The study also shows that student engagement increased with more students participating in science fairs and astronomy-related activities. However, participation in international follow-up activities organized by NASE and UNESCO remains limited. Encouraging greater involvement in these initiatives could strengthen Indonesia’s presence in global astronomy education and provide valuable networking opportunities.

In 2016, the Planetário do Porto – Ciência Viva Center (PP-CCV) launched a new approach to its in-service teacher training plan (TTP). This plan was structured around five key elements: (i) its relevance for teacher career progression, being free of charge and open to educators of all school subjects; (ii) an inquiry-based learning design, grounded in the most updated scientific knowledge and methods; (iii) a direct alignment with the school curriculum; (iv) the use Astronomy as a vehicle for interdisciplinary learning across several school subjects; and (v) a commitment to democratizing science leveraging the school system’s multiplier effect. In this article, we present the different stages in the development of the TTP, which include institutional partnership with NASE (Network for Astronomy School Education) and EAAE (European Association for Astronomy Education). The program enrolled 3,208 teachers from all the Portuguese districts as well as from the Community of Portuguese Speaking Countries (CPLP). The PP-CCV’s TTP, practical and replicable, proved to be an effective channel for bringing cutting-edge scientific knowledge and practices to educational contexts – especially in communities with historically low engagement with science, not by choice, but due to systemic barriers in access to scientific education.