Field Of Astronomy Research Articles

ASTRO WORLD EXHIBITION AND PLANETARIUM

This work has proposed the development of Astro World Exhibition and Planetarium center at Jeddah, Saudi Arabia. For this work, three case studies related to astronomical center were analysed. Based on the analysed case studies, for the planetarium center, the estimated gross floor area of the building is 8304 m2. This planetarium center is comprised of few zone, which are administration, exhibition, public zone, educational zone, IMAX theatre, and planetarium zone. Furthermore, in this work, two sites were proposed for constructing the planetarium center. Site evaluation analysis was carried out to determine the most suitable site. Few criteria's were evaluated, which are location, accessibility, shape, area, connectivity, land use, and orientation. Based on the result of the site evaluation analysis, site 1 attained the highest score of 55, compared to site 2 with evaluation score of 25. Thus, site 1 was selected as the proposed development site. In terms of architectural concept, the planetarium center was designed based on black hole concept. The Astro World Exhibition and Planetarium Center is expected to contribute to the local community in terms research in the field of astronomy in Saudi Arabia and to produce a nation that is well versed in the field of astronomy and space studies.

КОНСТРУЮВАННЯ ЗМІСТУ МІЖДИСЦИПЛІНАРНОГО КУРСУ СВІТОГЛЯДНОГО РІВНЯ ДЛЯ СТУДЕНТІВ ПЕДАГОГІЧНИХ УНІВЕРСИТЕТІВ

The article introduces causative-systemic approach implemented in a didactic model targeting the formation of scientific worldview. The said model is exercised while teaching master's school students the integrative course "Universal scientific worldview: methodology of natural science". This article highlights a number of aspects of modeling the natural-scientific component within the structure of this course. The paper discusses fundamental principles of theoretical modeling the content of future biology teachers' professional training and focuses on their application to natural scientific education as well as conditions of their realization.In the content of the suggested experimental course modern knowledge from the fields of biology, chemistry, astronomy, mathematics and physics is integrated and represented as a socio-cultural phenomenon that fits the universal laws of nature.

Mean-Square Risk of the Threshold Processing in the Problem of Inverting the Radon Transform with a Random Sample Size

Methods for reconstructing tomographic images based on the inversion of the Radon transform are used in problems arising in medicine, biology, astronomy, and many other fields. In the presence of noise in the projection data, as a rule, it is necessary to apply regularization methods. Recently, methods of the threshold processing of wavelet expansion coefficients have become popular. The analysis of errors of these methods is an important practical task, since it makes it possible to assess the quality of both the methods themselves and the equipment used. When using threshold processing, it is usually assumed that the number of expansion coefficients is fixed, and the noise distribution is Gaussian. This model is well studied in the literature, and the optimal values of the threshold processing parameters are calculated for different classes of functions. However, in some situations, the amount of data is not known in advance and has to be modeled with a certain random variable. In this paper, we consider a model with a random amount of data containing Gaussian noise, and estimate the order of the mean-square risk with an increasing number of decomposition coefficients.

Design and Characterizations of the Radiation-Hardened XCR4C ASIC for X-Ray CCDs for Space Astronomical Applications

Correlated double sampling (CDS) circuits are essential to processing the X-ray charge-coupled devices (CCDs) that have been widely used in the modern X-ray astronomical field. For timing observations, both energy resolution and timing resolution are of great importance. We are developing the XCR4C application-specific integrated circuit (ASIC), which is a fully customized four-channel radiation-hardened CDS ASIC targeting the readout of X-ray CCDs, for future space astronomical missions. The ASIC is implemented in a differential switched-capacitor architecture, making it highly linear, low power, immune to common-mode noise and interferences, as well as easily configurable. To combat the harsh low-earth-orbit space environment, some radiation-hardening techniques are applied, including the process hardening method, even-finger double-side bulk butting, and pseudo-double guard ring layout techniques. The XCR4C ASIC was fabricated with 0.35- $\mu \text{m}$ 2P4M CMOS technology with an epitaxial layer. The ASIC achieves a maximum 23-ppm integral nonlinearity and 5.8 e− rms equivalent noise charge under a typical 1-MHz pixel rate and only consumes 50 mW approximately from a single 3.3-V supply voltage. The results from radiation hardness assurance testing show that the ASIC has at least a total ionizing dose tolerance of 300 krad(Si), and no single-event latchup has been found up to a linear energy transfer of $81.35~\text {MeV}\cdot \text {cm}^{2}$ /mg with a total fluence up to $1.68\times 10^{7}$ ions/cm2.

The Luminosity Distribution of Short Gamma-Ray Bursts under a Structured Jet Scenario

Abstract The joint detection of gravitational wave (GW) and electromagnetic radiation from the binary neutron star merger event GW170817 marks a breakthrough in the field of multi-messenger astronomy. The short gamma-ray burst (sGRB) GRB 170817A, associated with this binary neutron star merger event, has an isotropic-equivalent gamma-ray radiation luminosity of 1.6 × 1047 erg s−1, which is much lower than that of other sGRBs. The measurement of the superluminal movement of the radio afterglow emission confirms the presence of the relativistic jet, and the emission features can be well explained by the structured jet model. In this paper, we calculate the luminosity distribution of sGRBs and its evolution with redshift based on the structured (Gaussian) jet model, and find that the typical luminosity increase with redshift, for nearby sGRBs (such as for luminosity distance less than 200 Mpc) the typical gamma-ray luminosity is just around 1047–1048 erg s−1, which naturally explains the very low radiation luminosity of GRB 170817A. We derived the detection probability of sGRBs by Fermi-GBM and found that the expected detection rate of sGRBs is only about 1 yr−1 within the distance of several hundred Mpc. We explored the effect of the power-law index α of the merger time distribution on the observed characteristics and found that it had little effect on the observed luminosity and viewing-angle distributions. However, it is very interesting that, for different values of α, the distributions of the number of observed sGRBs are quite different, so it is possible to determine the value of α through observed distributions of the number of sGRBs. We used the Bayesian method to make a quantitative analysis and found that the value of α may be identified when the number of observed sGRBs with known redshifts is more than 200. Finally, we compare our results of gamma-ray luminosity distribution with sGRBs with known redshifts, and found that our results are consistent with the observation, which implies that our simulation results can reproduce the observed luminosity distribution well.

Chemically distinct regions of Venus’s atmosphere revealed by measured N2 concentrations

A defining characteristic of the planet Venus is its thick, CO2-dominated atmosphere. Despite over 50 years of robotic exploration of Venus, including thirteen successful atmospheric probes and landers, our knowledge of N2, the second most abundant compound in the atmosphere, is highly uncertain1. We report the first measurement of the nitrogen content of Venus’s atmosphere at altitudes between 60 and 100 km. Our result, 5.0 ± 0.4 v% N2, is 40% higher than the value of 3.5 v% N2 reported for the lower atmosphere (<50 km altitude). Our discovery of altitude-dependent variations in the N2 content of the atmosphere defies early expectations of homogeneous composition below 100 km (for example, see ref. 1), and necessitates complete chemical modelling to investigate chemical versus physical explanations for the enhanced N2 in the upper atmosphere. The existence of chemically distinct lower and upper atmosphere regions complicates the use of remote sensing measurements of the upper atmosphere to infer the properties of the lower atmosphere and surface, an important lesson that also extends to the growing field of exoplanet astronomy. A MESSENGER flyby of Venus has detected a difference in N2 composition between the upper and lower atmosphere. The presence of substantially distinct regions within Venus’s atmosphere has implications on remote sensing techniques for exoplanets.

Electromagnetic Precursors to Gravitational-wave Events: Numerical Simulations of Flaring in Pre-merger Binary Neutron Star Magnetospheres

Abstract The detection of gravitational waves from neutron star merger events has opened up a new field of multimessenger astronomy linking gravitational-wave events to short gamma-ray bursts and kilonova afterglows. A further—yet to be discovered—electromagnetic counterpart is a precursor emission produced by the nontrivial interaction of the magnetospheres of the two neutron stars prior to merger. By performing special-relativistic force-free simulations of orbiting neutron stars we discuss the effect of different magnetic field orientations and show how the emission can be significantly enhanced by differential motion present in the binary, either due to stellar spins or misaligned stellar magnetospheres. We find that the buildup of twist in the magnetic flux tube connecting the two stars can lead to the repeated emission of powerful flares for a variety of orbital configurations. We also discuss potential coherent radio emission mechanisms in the flaring process.

The 3D non-LTE solar nitrogen abundance from atomic lines

Nitrogen is an important element in various fields of stellar and Galactic astronomy, and the solar nitrogen abundance is crucial as a yardstick for comparing different objects in the cosmos. In order to obtain a precise and accurate value for this abundance, we carried out N I line formation calculations in a 3D radiative-hydrodynamic STAGGER model solar atmosphere in full 3D non-local thermodynamic equilibrium (non-LTE). We used a model atom that includes physically motivated descriptions for the inelastic collisions of N I with free electrons and with neutral hydrogen. We selected five N I lines of high excitation energy to study in detail, based on their strengths and on their being relatively free of blends. We found that these lines are slightly strengthened from non-LTE photon losses and from 3D granulation effects, resulting in negative abundance corrections of around − 0.01 dex and − 0.04 dex, respectively. Our advocated solar nitrogen abundance is log ɛN = 7.77, with the systematic 1σ uncertainty estimated to be 0.05 dex. This result is consistent with earlier studies after correcting for differences in line selections and equivalent widths.

Gravitational waves in braneworlds after multi-messenger events

The GW170817 event opened a new window to test modifications to General Relativity with the aim of discard or impose strong constraints in extra dimension theories of gravity. Concerning these theories, the Randall–Sundrum brane-world theory – 4+1 spacetime model where its covariant Einstein field equations are composed with new extra terms that comes from extra dimensions – is begin tested in the multi-messenger astronomy field. In the same context, the aim of this paper is to impose new constrictions through measurements of the time-delay between the gravitational and electromagnetic signals: GW170817 and the recent S190425z, over the free cosmological parameters of this modified model. We assume that Gravitational Waves travel along a shortcut on the extra dimension. In addition, we consider the standard Lambda CDM model and perform a likelihood analysis in order to study effects like the H_0 tension in comparison to this extra-dimensional theory, obtaining a reduced H_0 value of the order of 0.2% in the low energy limit of this theory.

Effective temperatures of red supergiants estimated from line-depth ratios of iron lines in the YJ bands, 0.97-1.32μm

ABSTRACT Determining the effective temperatures (Teff) of red supergiants (RSGs) observationally is important in many fields of stellar physics and galactic astronomy, yet some significant difficulties remain as a result of the model uncertainty, which originates mainly in the extended atmospheres of RSGs. Here we propose a line-depth ratio (LDR) method in which we use only Fe i lines. As opposed to the conventional LDR method, in which lines of multiple species are involved, this LDR method is insensitive to surface gravity effects and is expected to circumvent the uncertainty originating in the upper atmosphere of RSGs. Therefore, the LDR–Teff relationships that we calibrated empirically with red giants can be directly applied to RSGs, although various differences between the two groups of objects, for example caused by 3D non-local thermodynamic equilibrium (non-LTE) effects, need to be kept in mind. Using the near-infrared YJ-band spectra of nine well-known solar-metallicity red giants observed with the WINERED high-resolution spectrograph, we selected 12 pairs of Fe i lines that were the least contaminated with other lines. After applying their LDR–Teff relation to 10 nearby RSGs, the resulting Teff with an internal precision of $30\!-\!70\, \mathrm{K}$ shows good agreement with previous observational results assuming 1D LTE and with the Geneva stellar evolution model. We found no evidence of significant systematic bias caused by various differences, including those in the size of the non-LTE effects, between red giants and RSGs, except for one line pair that we rejected because the non-LTE effects may be as large as $\sim \! 250\, \mathrm{K}$. Nevertheless, it is difficult to evaluate the systematic bias, and further study is required, for example including the 3D non-LTE calculations of all the lines involved.

Gravitational-Wave Observations by Advanced LIGO and Virgo

From September 2015 until August 2017, the Advanced LIGO and Virgo gravitational-wave detectors conducted their first two observing runs O1 and O2. Since the milestone detection of gravitational waves from two coalescing black holes, GW150914, a further nine binary black holes collisions as well as one binary neutron star inspiral have been identified, firmly establishing the field of gravitational-wave astronomy. After a commissioning break, the third observing run commenced on April 1, 2019 which has since seen the public announcement of several tens of gravitational-wave candidate events. In this proceedings, we summarise the observations during O1 and O2 and briefly discuss the current status.

“Quantum Weirdness” in Exploitation by the International Gravitational‐Wave Observatory Network

AbstractThe detectors of the international gravitational‐wave (GW) observatory network are currently taking data with sensitivities improved via squeezing the photon counting noise of the laser light used. Several GW candidate events, such as black‐hole mergers, are already in the pipeline to be analyzed in detail. While the brand‐new field of GW astronomy relies on squeezed light for reaching higher sensitivities, the physical understanding of such light, although being well described by quantum theory, is still under discussion. Herein, a physical description of why squeezed light, as now being exploited by GW observatories, constitutes rather remarkable physics is presented. Consideration of the Fourier transform seems to provide an argument why the measurement of squeezed photon statistics from quasi‐monochromatic light is “weird.” It is further argued that the measurement of squeezed photon statistics is related to the famous gedanken experiment formulated by Einstein, Podolsky, and Rosen in 1935. This work illuminates “quantum weirdness” in a clear way and might be the starting point for finding the physics of quantum correlations in general, which scientists have been seeking for decades.

The genitourinary and reproductive systems: Interpretation of Avicenna's (980–1037 AD) treatise in the Canon of Medicine

Avicenna (also known as Ibn Sina 980–1037 AD) was the most influential Persian physician and scholar in the medieval times (9–12th century AD). Avicenna contributed to various fields of medicine, astronomy and metaphysics during his time. In the field of basic medical sciences, Avicenna systematically described the anatomy and pathology of various organs of the human body and devised surgical interventions towards the treatment of disorders associated with them. Avicenna compiled his famous book the Canon of Medicine which went on to become a reference textbook of medicine in the region and the West. Although neither formal human cadaveric dissection nor surgical training was recorded during his time, the anatomical and surgical information presented in the Canon of Medicine is comparable to modern literature. In the current vignette, we present an analysis of the basic structural anatomy and functional aspects of the genitourinary and reproductive systems and some reproductive concepts presented in the Canon of Medicine textbook and compare their relevance in modern medical literature. We found Avicenna's information on these systems to be congruent to modern anatomy and physiology literature. The only differences are attributed to the differences in the experimental approaches with Avicenna's information being derived in an era with less technological advances especially on the histology of organs. However, Avicenna's information in this treaty can be regarded as pioneering in the fields of urology and gynaecology.

The State of Astronomy Education in Iran: Challenges and Solutions

Astronomy has a long history in Iran. Our ancestors were pioneered in astronomy and from ancient years was an excelled country in the construction and use of astronomical buildings. Today, there are more than 200 local astronomical societies and centers in the country that the amateur astronomy community has played a significant and influential role in the education and promotion of astronomy to the general public since 2000. A greater part of astronomy education was provided by amateur astronomers through outreaching events, observing nights, and education and outreach projects. Another part of it has been disseminated by science journalists who are amateur astronomers and astronomer teachers in the media and newspapers. Considering the enormous potential that has existed in the growth and development of Iranians in the field of astronomy, in the meantime, challenges such as the specific cultural and social constraints for women's activities, lack of sufficient knowledge of the teachers as well as the training required for them, the lack of a standard curriculum for teaching astronomy and network of astronomy teachers, and also economic barriers, have caused socio-economic development and education through Astronomy to grow less in Iran. This survey suggests challenges for teaching astronomy in general.

Photon arrival time tagging with many channels, sub-nanosecond deadtime, very high throughput, and fiber optic remote synchronization.

Time-Correlated Single Photon Counting (TCSPC) and time tagging of individual photon detections are powerful tools in many quantum optical experiments and other areas of applied physics. Using TCSPC, e.g., for the purpose of fluorescence lifetime measurements, is often limited in speed due to dead-time losses and pileup. We show that this limitation can be lifted by reducing the dead-time of the timing electronics to the absolute minimum imposed by the speed of the detector signals while maintaining high temporal resolution. A complementing approach to speedy data acquisition is parallelization by means of simultaneous readout of many detector channels. This puts high demands on the data throughput of the TCSPC system, especially in time tagging of individual photon arrivals. Here, we present a new design approach, supporting up to 16 input channels, an extremely short dead-time of 650 ps, very high time tagging throughput, and a timing resolution of 80 ps. In order to facilitate remote synchronization of multiple such instruments with highest precision, the new TCSPC electronics provide an interface for White Rabbit fiber optic networks. Beside fundamental research in the field of astronomy, such remote synchronization tasks arise routinely in quantum communication networks with node to node distances on the order of tens of kilometers. In addition to showing design features and benchmark results of new TCSPC electronics, we present application results from spectrally resolved and high-speed fluorescence lifetime imaging in medical research. We furthermore show how pulse-pileup occurring in the detector signals at high photon flux can be corrected for and how this data acquisition scheme performs in terms of accuracy and efficiency.

A novel image classification model based on adversarial training for pulsar candidate identification

Pulsars are highly magnetized, rotating neutron stars with small volume and high density. The discovery of pulsars is of great significance in the fields of physics and astronomy. With the development of artificial intelligent, image recognition models based on deep learning are increasingly utilized for pulsar candidate identification. However, pulsar candidate datasets are characterized by unbalance and lack of positive samples, which has contributed the traditional methods to fall into poor performance and model bias. To this end, a general image recognition model based on adversarial training is proposed. A generator, a classifier, and two discriminators are included in the model. Theoretical analysis demonstrates that the model has a unique optimal solution, and the classifier happens to be the inference network of the generator. Therefore, the samples produced by the generator significantly augment the diversity of training data. When the model reaches equilibrium, it can not only predict labels for unseen data, but also generate controllable samples. In experiments, we split part of data from MNIST for training. The results reveal that the model not only behaves better classification performance than CNN, but also has better controllability than CGAN and ACGAN. Then, the model is applied to pulsar candidate dataset HTRU and FAST. The results exhibit that, compared with CNN model, the F-score has increased by 1.99% and 3.67%, and the Recall has also increased by 6.28% and 8.59% respectively.

Scientometric Study of Astronomy and Astrophysics Research in India (1994 – 2015): An Analysis from Astrophysics Data System

A scientometric study evaluation of India’s scientific research output in the field of astronomy and astrophysics during 1994–2015 has been done. The bibliographic data were harvested from Astrophysics Data System Database (ADSD) for a period of 22 years from 1994 to 2015. The compound annual growth rate, collaboration trends, authorship pattern, growth rate and doubling time, degree of collaboration, highly productive authors are examined. India is holding 15th rank in the field of astronomy and astrophysics research in the world and it is found that 9.09% was the average CAGR of Indian astronomy and astrophysics publications during the study period. It is also found that India has published 83.67% of research papers as journal articles, 11.88% publication as conference papers. The degree of collaboration is 0.86. The study revealed that collabor ative research is most preferred and focused as multi authorship pattern of publication; 3815 papers were two–authored followed by 3250 papers with three–authors during the study period.

Promoting gender equality in the European astronomical community

Striving for equality means striving for an equal, inclusive and diverse world. Gender is just one facet of the broader theme of diversity. Years of dedicated efforts to tackle gender equality in the workforce and throughout society in Europe show positive trends, but the timescales involved in implementing changes and making them effective means equality between women and men remains an important goal yet to be achieved by the majority of players (be these institutes, universities, research organizations or companies). This Perspective reports on the most recent initiatives in science and technology, with a special focus on the field of astronomy. Years of dedicated efforts to tackle gender inequality in Europe show positive trends, but equality has not yet been achieved. This Perspective reports on the most recent initiatives in science and technology, with a special focus on the field of astronomy.

The AstroCamp Project

AbstractThis contribution describes the concept, main structure and goals, and some highlighted outcomes, of the AstroCamp—an international academic excellence program in the field of astronomy and physics created in 2012 and organized by Centro de Astrofsica da Universidade do Porto (CAUP) together with the Paredes de Coura municipality and several national and international partners.

RADIO ASTRONOMY AT CORNELL UNIVERSITY: THE EARLY YEARS, 1946 TO 1962

In 1946 the Microwave Astronomy Project was initiated by the School of Electrical Engineering at Cornell University, the first university in the United States to enter the new field of radio astronomy as it was later called. While the Engineering School's Director, Charles Burrows, led the project, the initiative came from Charles Seeger, a faculty member in Electrical Engineering, and two instructors in the Department of Astronomy, Ralph Williamson and Donald McRae, both of whom left Cornell in 1946. With funding from the U.S. Office of Naval Research, two World War II SCR-268 radar systems, which operated at 200 MHz, were acquired and plans made to construct a 6-m diameter parabolic antenna that would operate at frequencies up to 10 GHz. A site was chosen about 8 km from the Cornell university campus. The parabolic antenna was completed in 1948 although using a borrowed 5-m reflector that, initially, could only operate up to 200 MHz. Its completion in October was in conjunction with the first conference on radio astronomy held in the United States, which attracted considerable publicity for this new research field. Initial observations of the Sun were made in June 1948 using the two receiving 4 × 6 dipole arrays from the SCR-268 radars mounted on the elevation arm of one of the radar systems. This was followed by routine solar observations from July 1948 to December 1949. Initial results were published by Martha Stahr, Assistant Professor of Astronomy at Cornell. During the summer and fall of 1948 two more observational programs were started. Charles Seeger and Ralph Williamson determined the direction of the radio pole of our Galaxy using the SCR-268 mattress array and Seeger did extensive observations of the strong variable source Cygnus A using, initially, the mattress array and, later, the 5-m antenna. In late 1949 Leif Owren joined the project to pursue a doctoral degree based on solar radio observations. These started in mid-1950 and continued until December 1952, initially with the 5-m antenna and, later, with the mattress array while the 5-m antenna was being resurfaced to allow operation at1,420 MHz. Owren also built a two element interferometer to study the relationship between solar radio bursts andoptically observed plages and sunspots. Charles Seeger left Cornell in 1950 and Owren in 1952, leaving noastronomers with a strong interest in the radio astronomy program until Marshall Cohen joined the faculty in 1954.Cohen initiated studies of the polarization properties of solar radio emission with the 5-m antenna that continued intothe 1960s both at the original site and, after 1962, at a new site south-east of Cornell University in the town of Danby.Only the 5-m antenna was moved to this site and it was decommissioned when the radio astronomy technical group,which by this time was primarily working in support of the newly built Arecibo 305-m telescope, was again moved to asite closer to Cornell University.