American Research Journal of Physics

Ezeani, S1, Sigalo, F.B1, Israel-Cookey, C1, Alibaba M.A. 

Abstract This research is on the Photometric observation of Variable star AO Ser so as to observe and report the eclipse phenomenon. The target was observed with the 0.4m SBIG optical telescope from Las Cumbres Observatory Global Telescope Network remotely. The photometric analysis was done using SAO Image Viewer (DS9) and IRIS software which enabled us to plot the light curve the deduce eclipses. Results from our photometric analysis revealed that AO Ser is an eclipsing binary variable star with significant flares. The average values of from the analysis of the V-filter of AO Ser, gaveA1 = 1.35, A2 = 0.229, D1 = 187×103 hrs. (51.94secs), D2 = 78.4×103 hrs. (21.7secs) and d1 = 25.4×103 hrs. (7.055secs), d2 = 0hrs (0secs) while the B-filter gaveA1 = 0.64, A2 = 0.143, D1 = 184×103 hrs. (51.11secs), D2 = 76.5×103 hrs. (21.25.0secs) and d1 = 25.0×103 hrs. (6.944secs), d2 = 0hrs (0secs) respectively. The value of d2 = 0secs were the same both for V and B Filters observation, demonstrating that the primary candidate of AO Ser is smaller than its secondary companion, hence the secondary component was not totally eclipsed. The results from our photometric data showed that AO Ser is an eclipsing star with an average surface temperature of 9447K classifying the source as a red giant. 

Xinxin Wang1, Ye-Zhao Yu2, 3

Abstract Fast radio bursts are a class of transient radio sources that are thought to originate from extragalactic sources since their dispersion measure greatly exceeds the highest dispersion measure that the Milky Way interstellar medium can provide. Host Galaxies of twenty-two fast radio bursts have already been identified [1]. In this paper, the dispersion measurement of these fast radio bursts produced by the Milky Way interstellar medium, and the intergalactic medium is obtained through known physical models to yield the host galaxy dispersion measure. It is observed that the host galaxy dispersion measure increases with its redshift value. We also obtained that the host galaxy dispersion measure has different distribution between repeaters and non-repeaters. It is noted that the reason for the divergence of the host galaxy dispersion measures should be accounted for by the difference in their local environment.