arXiv subjects

J. Adassuriya

Publications and source records attributed to J. Adassuriya.

5 recordsLinked to original sources

arXiv2026

e-CALLISTO FITS Analyzer: A Software Framework for CALLISTO Solar Radio Data

Solar radio bursts are important signatures of dynamic processes in the solar corona, including particle acceleration and shock propagation associated with solar flares and coronal mass ejections. Among the missions that report solar radio bursts within 24 hours, the e-CALLISTO archive is the largest, with more than 150 stations worldwide. The archive generates large volumes of FITS data that are often affected by radio-frequency interference and background noise. Irregular frequency setups in different stations are also a limitation of statistical analysis of SRBs. Each CALLISTO observation is a 15-minute frame, which often causes a single burst to split over multiple frames, making event-level analysis difficult. This work presents the e-CALLISTO FITS Analyzer, a unified, interactive, cross-platform application for processing and analyzing e-CALLISTO dynamic spectra on Windows, macOS, and Linux. The application supports time and frequency merging to produce a continuous spectrum, applies mean background subtraction with user-controlled threshold clipping, and isolates burst regions through an interactive polygon mask in the time-frequency plane. It also extracts the maximum-intensity backbone, allows interactive outlier removal, and performs power-law fitting to estimate drift rates and derive shock height and speed using the Newkirk model, including $n$-fold scaling. For a Type II burst observed by Arecibo Observatory on 2 March 2022, the analyzer yielded an average drift rate of $-0.0400 \pm 0.0003\, MHz/s$ and an average shock speed of $449 \pm 1\, km/s$ at a height of $1.715 \pm 0.002\, R_{\odot}$. The e-CALLISTO FITS Analyzer supports more reproducible, event-focused SRB analysis and improves access to physically meaningful measurements from e-CALLISTO FITS data.

astro-ph.SR↗

arXiv2025

Light Curve Modeling of Eclipsing Binary Systems with Delta Scuti Component

Astroseismology in eclipsing binaries with Delta ($δ$) Scuti components offers a powerful means to derive stellar parameters and probe internal structures. To enable accurate frequency analysis, binary characteristics must be disentangled from the observed light curves. This study utilizes the LC2015 light curve modeling method, followed by the DC2015 differential correction process, integrated into the Wilson-Devinney (WD) eclipsing binary modeling code. The analysis focuses on two $δ$ Scuti binary systems, KIC 8504570 and SX DRACONIS (Dra), using Kepler and TESS photometric data, supplemented by literature-derived initial stellar parameters. The DC2015 process employs the Levenberg-Marquardt algorithm to minimize the difference between observed and modeled light curves. The refined models provide highly accurate stellar parameters, including primary and secondary star temperatures ($T_{eff},1$ and $T_{eff},2$), mass ratio (q), and primary star luminosity (L1) with associated errors. For KIC 8504570: $T_{eff},1$ (7400.9 $\pm$ 1.6) K, $T_{eff},2$ (5450.0 $\pm$ 1.0) K, q (0.5208 $\pm$ 0.0002), and L1 (11.8043 $\pm$ 0.0006)$L_\odot$. For SX Dra: $T_{eff},1$ (7729.7 $\pm$ 1.1) K , $T_{eff},2$ (4927.5 $\pm$ 0.5) K, q (0.4772 $\pm$ 0.0006), and L1 (7.0474 $\pm$ 0.0015)$L_\odot$.

astro-ph.SR↗

arXiv2025

Determination of Speed and Source Height of Coronal Shock Waves Using Type II Solar Radio Bursts

This study examines the shock speed and source height of coronal shock waves using Type II solar radio bursts. The solar radio burst data from January 2022 to October 2023 were obtained from eCALLISTO archive. The type II radio bursts were isolated from the spectra through a rigorous noise reduction process by taking the maximum intensity of each time channel. Using plasma oscillations and electron density models for the solar corona, explicit expressions for shock speed and source height were obtained. From the dynamic spectra, the starting frequency of a burst was obtained and using these parameters shock speed and source height were calculated. Results confirmed shock speeds ranging from 343 to 1032 kms$^{-1}$ with average speed of 650$\pm$226 kms$^{-1}$ and source heights 1.317-1.724 R$_\odot$, with high precision in formula predictions. The study highlights the need for broader burst type inclusion in future research and underscores the efficacy of the developed methodologies to improve space weather forecasts.

astro-ph.SR↗

arXiv2023

Spectroscopic observations of novae V1065 CEN and V1280 SCO using 45 cm cassegrain telescope at Arthur C Clarke Institute

The spectroscopic observations of two novae namely V1065 CEN and V1280 SCO were made by 45 cm Cassegrain telescope in high resolution ($λ/δλ$=22000) at H$α$ (6563 Å) region. V1065 CEN is He/N-type spectra which characterize a broad (Gaussian FWHM 49 Å), saddle shaped and asymmetric H$α$ emission line without prominent P-Cyg absorption component. Completely different H$α$ profile of V1280 SCO shows prominent P-Cyg absorption and narrow emission line (Gaussian FWHM 26 Å) which can be classified as Fe II type nova. The expansion velocities of these two systems measured from the minima of the P-Cyg profiles are close to 2300 km/s for V1065 CEN, and 716 km/s for V1280 SCO. Based on the photometric analysis, the Nova V1065 CEN can be classified as fast (11$<$t${_2}$$<$25) nova. The derived absolute magnitudes at maximum for nova V1065 CEN to be M$_{o,V}$ = -7.58$\pm$0.18 and M$_{o,B}$= -7.75$\pm$0.25 correspond to a distance 8.51$\pm$0.33 kpc. The parameters t$_{2V}$=12 days and t$_{3V}$=14 days of nova V1280 SCO determine that the nova is in between very fast and fast nova. The mean absolute magnitude at maximum is calculated to be M$_{o,V}$=-8.7$\pm$0.1 and the estimated distance to the nova V1280 SCO is 3.2$\pm$0.2 kpc.

astro-ph.SR↗

arXiv2020

Asteroseismology of sz lyn using multi-band high time resolution photometry from ground and space

We report the analysis of high temporal resolution ground and space based photometric observations of SZ Lyncis, a binary star one of whose components is a high amplitude $δ$ Scuti. UBVR photometric observations were obtained from Mt. Abu Infrared Observatory and Fairborn Observatory; archival observations from the WASP project were also included. Furthermore, the continuous, high quality light curve from the TESS project was extensively used for the analysis. The well resolved light curve from TESS reveals the presence of 23 frequencies with four independent modes, 13 harmonics of the main pulsation frequency of 8.296943$\pm$0.000002 d$^{-1}$ and their combinations. The frequency 8.296 d$^{-1}$ is identified as the fundamental radial mode by amplitude ratio method and using the estimated pulsation constant. The frequencies 14.535 d$^{-1}$, 32.620 d$^{-1}$ and 4.584 d$^{-1}$ are newly discovered for SZ Lyn. Out of these three, 14.535 d$^{-1}$ and 32.620 d$^{-1}$ are identified as non-radial lower order p-modes and 4.584 d$^{-1}$ could be an indication of a g-mode in a $δ$ Scuti star. As a result of frequency determination and mode identification, the physical parameters of SZ Lyn were revised by optimizations of stellar pulsation models with the observed frequencies. The theoretical models correspond to 7500 K $\le $T$_{\rm eff}$ $\le$ 7800 K, log(g)=3.81$\pm$0.06. The mass of SZ Lyn was estimated to be close to 1.7--2.0 M$_\odot$ using evolutionary sequences. The period-density relation estimates a mean density $ρ$ of 0.1054$\pm$0.0016 g cm$^{-3}$

astro-ph.SR↗