Open Access Original Research Article

Deep Learning Techniques to Make Gravitational Wave Detections from Weak Time-series Data

Yash Chauhan

International Astronomy and Astrophysics Research Journal, Page 1-9

Gravitational waves are ripples in the space time fabric when high energy events such as black hole mergers or neutron star collisions take place. The first Gravitational Wave (GW) detection (GW150914) was made by the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo Collaboration on September 14, 2015. Furthermore, the proof of the existence of GWs had countless implications from Stellar Evolution to General Relativity. Gravitational waves detection requires multiple filters and the filtered data has to be studied intensively to come to conclusions on whether the data is a just a glitch or an actual gravitational wave detection. However, with the use of Deep Learning the process is simplified heavily, as it reduces the level of filtering greatly, and the output is more definitive, even though the model produces a probabilistic result. Our technique, Deep Learning, utilizes a different implementation of a one-dimensional convolutional neural network (CNN). The model is trained by a composite of real LIGO noise, and injections of GW waveform templates. The CNN effectively uses classification to differentiate weak GW time series from non-gaussian noise from glitches in the LIGO data stream. In addition, we are the first study to utilize fine-tuning as a means to train the model with a second pass of data, while maintaining all the learned features from the initial training iteration. This enables our model to have a sensitivity of 100%, higher than all prior studies in this field, when making real-time detections of GWs at an extremely low Signal-to-noise ratios (SNR), while still being less computationally expensive. This sensitivity, in part, is also achieved through the use of deep signal manifolds from both the Hanford and Livingston detectors, which enable the neural network to be responsive to false positives.

Open Access Original Research Article

Teachers’ and Students’ Perceptions on Introduction of Astrophysics in Bhutanese Curriculum: An Exploratory Study

Tashi Dendup, Karma Utha, Ugyen Pem

International Astronomy and Astrophysics Research Journal, Page 10-21

Astronomy education is rapidly growing because of its significant benefits to everyday life. Hence, Royal Education Council has introduced Astrophysics content for Bhutanese students in the curriculum from 2015. Royal Education Council is the highest decision-making body that initiate and implement educational reforms and school curriculum in Bhutan. Using Mixed-methods approach, this study investigated the perceptions of teachers and students on introduction of Astrophysics in Bhutanese curriculum. The study was carried out in four schools under Trashigang District from 1st March to 20th March 2020. The data were collected through survey questionnaire and structured interview. The sample comprised of 298 students (119 male and 179 female) and 11 teachers. The study found out that the teachers and students possess negative perceptions towards teaching and learning of Astrophysics. For majority of the students, the concepts of Astrophysics were found to be abstract and difficult to understand. The study also revealed that the students’ find difficult to see the real-life applications of Astrophysics concepts as well as had minimal knowledge on the relevant career opportunities in future. Some of the recommendations from the study include revisiting the content on Astrophysics to make it suitable for the learners, focus on teacher preparation and make students aware of the career opportunities.

Open Access Original Research Article

Law and Equation of Interplanetary Relationship and its Applications

Rajat Saxena

International Astronomy and Astrophysics Research Journal, Page 22-32

In classical theory, it is believed that physical characteristics of a planet like the axial tilt, the orbit radius, and the rotation period are independent quantities, meaning they are not directly related to each other. However, this paper will discuss a simple yet elegant equation that shows all these quantities are interlinked. The Interplanetary Relationship equation shows that for a planet, the ratio of axis tilt to the product of orbit radius and rotation period is a constant. The value of this constant is the topic of further discussion in the paper. The equation is a subject of beauty, as it relates quantities that seem to be independent of each other. The law and its equation have various applications, which will be discussed further in the paper and improve our understanding of the solar system. 

Open Access Original Research Article

Singly Ionized Iridium Spectral Lines in the Atmosphere of Hot Stars

Zoran Simic´, Nenad M. Sakan, Nenad Milovanovic, Mihailo Martinovic

International Astronomy and Astrophysics Research Journal, Page 33-47

The electron-impact broadening parameters of ion lines are of interest for a number of problems in astrophysical, laboratory, and technological plasma investigations. Singly ionized Iridium lines are confirmed their presence in stellar spectra of the chemically peculiar stars. Our calculations are performed using the modified semiempirical method of Dimitrijevic and Konjevi ´ c. Stark widths for ´ 301 Ir II spectral lines are presented. From the calculated list of lines, the 21 strongest lines from the iridium spectrum are selected with high value of intensity ≥ 3000 to demonstrate importance of the Stark broadening mechanism for different types of stars. The analysis of the electron-impact effect on spectral line shapes are performed and obtained Stark and Doppler withds are compared.

Open Access Original Research Article

Closer Look at the Contracting Solar Nebula

J. J. Rawal, Nishant Malhotra

International Astronomy and Astrophysics Research Journal, Page 48-61

Rawal [1 to 11] studied the contraction of the Solar Nebula in order to understand the formation of the Solar System and to derive Planetary Distance Law. He took the view that the Solar Nebula contracted in steps of Roche Limit. Roche Limit is defined as the three dimensional distance on entering which the secondary body breaks into pieces due to tidal forces of the primary. Alternatively, it is the three-dimensional distance within which the primordial matter which is left behind around the primary, after its formation, does not get condensed into a secondary, due to tidal forces of the primary. In his paper entitled “Contraction of the Solar Nebula”, Rawal (afore-mentioned papers) took the assumption that the ratio of the density of the primary  to the density of the secondary , which appears in the formula of Roche Limit, is of the order unity, that is, ( . In order to get closer look in the contraction of the Solar nebula, here, in this paper, we would like to remove this restriction on the ratio (  and take it to be 0.7, 0.8, 0.9 or 1.1, 1.2, 1.3 and derive the distances of outer and inner edges of the gaseous rings, which one by one, go to form secondaries around the primary (here, the Sun), out of which planets were formed. This may give us closer look of the contraction of the Solar Nebula which is going to form the Solar System, giving rise to the form of Planetary Distance Law, consistent with 2/3-stable Laplacian Resonance Relation, which may be closer to reality. After going through this exercise, it is found, here, that the assumption that ( = 1 may be relaxed. If it is less than 1, the system is shrunk and if it is more than 1 the system expands, only the Scale-parameter changes, the structure remains similar. However, in all these cases resonance necessarily will not be stable 2/3-Laplacian resonance. For stable 2/3-Laplacian resonant orbits, the ratio (  is utmost necessary. One, therefore, concludes that the orbits in the Solar System are stable because the ratio ( ) involved in the Roche Limit, is of the order unity.