It is important to understand stellar evolution as well as the chemical composition and structure of the Galactic disk, in which B stars in open clusters play a major role as they are of the most massive and brightest objects in these clusters. The fundamental atmospheric parameters (Teff, log g) of the B stars in the Alpha Persei open cluster (190pc, 50Myrs) have been determined using the Stromgren uvby-β photometric system, with a calibration technique by Napiwotzki et al. (1993)[65]. The method is based on fitting spectral lines of fundamental stars to synthetic spectra based on Kurucz ...
The Dark Ages, a period stretching from 400 thousand years to 400 million years
after the big bang, is the least known era in the evolution of our universe, as no
visible light was emitted. However, another type of radiation was available, the
Hydrogen 21cm. It reaches us at frequencies between 1.5 and 30MHz. The ideal
way to detect it, involves antennas placed in a fixed orbit around the dark side of the
moon where it is shielded from electromagnetic interference emitted from earth.
Exoplanets are planets orbiting stars other than our Sun. During their motion around their star, due to gravitational effects, and due to the planet’s thermal and reflective radiation, small variations in the lightcurve could be detected (Esteves et al. 2015). Phasecurves are small-scale variations in planetary flux that arise from an exoplanet’s motion around its host star. If detected, the phasecurve can lead to determining the planet’s mass, its albedo, and it can give us an idea about its atmosphere. In this work we aim to detect these variations in the data from the K2 mission. To do this we ...
This study is part of a newly growing science in exoplanet characteristics. We present an initial attempt to investigate the relationship between the eclipse depth of giant exoplanets and the metallicity of their host stars to show the best eclipse depth-metallicity trend. This will help us to better understand the conditions that lead to giant planets formation, which helps to postulate about the formation of our Solar System and more generally the planet formation theories. Previous studies have shown that stars with giant planets tend to have higher metallicities than stars without giant ...
Der Sahaguian, Elias Ohannes(Notre Dame University-Louaize, 2019)
Low-Ionization Nuclear Emission-Line Regions (LINERs) represent the low luminosity end of Active Galactic Nuclei (AGN). The main power source of LINERs is the subject of considerable debate in the scientific community today, despite the fact that some Liners show features of mass accretion into a super massive black hole (SMBH). Optical line-ratio diagrams are not conclusive diagnostic tools as they can be explained by different mechanisms, including shocks (Dopita et al. 1997[8]) and photoionization accompanied by outflow resembling accretion (Sabra et al. 2003[23]). This dissertation will ...