Browsing by Author "Sarkar, Tamal"

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Open Access
Estimating Mass and Luminosity of Spectroscopic Binary Stars Using a Python-Based Computational Approach
(University of North Bengal, 2025-03) Kundu, Jayashree; Mandal, Rakesh Kumar; Sarkar, Tamal
Spectroscopic binary stars provide crucial insights into stellar masses, orbital dynamics, and evolutionary processes. This study presents a computational approach to analyzing spectroscopic binary systems using Python by developing an algorithm to estimate their mass and luminosity. In our study, the algorithm processes the spectral data, particularly variations in the Hydrogen-alpha line over time (in Modified Julian Date), to compute radial velocities by incorporating Doppler shifts and applying barycentric corrections. A sinusoidal function is then fitted to the velocity variations to determine the orbital period. The stellar masses are derived using the radial velocity curve with the inclination angle and orbital parameters. Given the mass-luminosity relation, the luminosities of the stars are estimated. Since the derived mass of the system ranges between 2 and 55 times the mass of the sun, the luminosity can be calculated based on the mass-luminosity relation, where luminosity is proportional to the stellar mass raised to the power of 3.5. This computational method offers an efficient and accurate technique for studying spectroscopic binaries, which can be extended to analyze large datasets from astronomical surveys, enhancing our understanding of binary star evolution.
Open Access
Search for some observational signatures of general relativity
(University of North Bengal, 2017) Sarkar, Tamal; Bhadra, Arunava
Open Access
Spectral variability in the orbital profiles of TeV Binary LSI + 61o 303 in X-Ray window using XMM - Newton Observations
(University of North Bengal, 2024-03) Sarkar, Tamal
LSI + 61o 303 is a high-mass X-ray binary consisting of a low-mass [M (1 - 4)M o] compact object orbiting around an early type B0 Ve star along an eccentric e = 0:7 orbit. It along with LS5039 are the only two known gamma-ray binary detected in the TeV band. Despite extensive observations the nature of this source, particularly whether it is a pulsar or a black hole (microquasar) system, is not clear. The mechanisms that lead to the multi-wavelength behavior are also uncertain. Recent approach to the study of LSI + 61o 303 has been to focus on possible correlated variability. There was an early indication that there is a correlation between the X-ray and TeV emission at the time where the latter was measurable. In a more recent observation, however, such a feature has not been found. In this work, we study the spectral variability of LSI + 61o 303 using four observations between 2001 to 2007 of XMM - Newton available from NASA archive and examine the correlation between low energy range and high energy part.