|
|
Distance to nearby galaxies
Šándorová, Ivana ; Zasche, Petr (advisor) ; Wolf, Marek (referee)
Title: Distance to nearby galaxies Author: Ivana Šándorová Institute: Astronomical Institute of the Charles University Supervisor: doc. RNDr. Petr Zasche, Ph.D., Astronomical Institute of the Charles University Abstract: The present work is focused on the study of the variable stars, particularly the lumi- nosity of cepheids in The Large Magellanic Cloud. The data were obtained from photometric observations of starfield (image centre coordinates: RA: 5◦13 36 , DE: −69h 22m 42s) using the 1,54 m Danish telescope at the observatory La Silla in Chile. The aim of this work was to find the distance of Large Magellanic Cloud, which was determined by the "period - lu- minosity relation" method for cepheids. We studied 13 cepheids, which were compared with one non-variable star. We computed the average value of distance modulus as (18,42 ± 0,40) mag. The distance modulus from the latest publication (Pietrzi'nski, G. and others, 2019) is (18,477 ± 0,004 (statistic) ± 0,026 (systematic)) mag. SIPS (Scientific Image Processing System) is software for measuring and processing of images of star field and was used in this work for processing of photometric images of star field. Own program was used for creating and editing the light curves. Keywords: galaxy, variable stars, cepheids, distance modulus 1
|
|
|
Distance to the Magellanic clouds
Kulich, Matúš ; Zasche, Petr (advisor) ; Korčáková, Daniela (referee)
Twelve eclipsing binary systems from the region of the Large Magellanic Cloud have been studied in this thesis in order to calculate the distance. The photometric data come from the OGLE survey carried out at the Las Campanas Observatory in Chile and the spectroscopic data come from other papers where they had already been partially ana- lyzed for other purposes. From these data, the light curves and the radial velocity curves of these systems have been constructed and analyzed using the PHOEBE soft- ware, in which the physical parameters and the absolute magnitudes of their individual components have been determined by the method of synthetic curves. By comparing them to the observed apparent magnitudes in I-band deduced from the light curves and taking into account the bolometric corrections and the V-I indices, the distance modu- lus of the Large Magellanic Cloud could be determined to be 18.59 ± 0.4 mag, which fairly corresponds to the quite familiar results determined by using this and other meth- ods in various research papers. However, in order to determine the distance modulus more accurately, it would be necessary to use accurate, much more complex models of stellar atmospheres and not simply rely on the general relations of the main-se- quence stellar parameters, which exhibit quite a large variance.
|
guest ::
