Please use this identifier to cite or link to this item:https://hdl.handle.net/20.500.12259/117551
Type of publication: master thesis
Field of Science: Fizika / Physics (N002)
Author(s): Fokas, Vytautas
Title: Žvaigždžių klasifikacijos galimybės GAIA fotometrinėje sistemoje
Other Title: Star Classification Possibilities in the GAIA Photometric System
Extent: 82 p.
Date: 8-Jun-2006
Keywords: stars;synthetic photometry;klasifikacija;sintetinė fotometrija;classification;žvaigždės
Abstract: The possibilities of the classification of simulated observations in the GAIA photometric system are investigated. The data simulated by Barselona group [gaia.am.ub.es] from the BaSeL-2.2 and NextGen2 libraries of synthetic spectra are used. At first, the flux distribution curves of synthetic spectra for NextGen model atmospheres [ftp.hs.uni-hamburg.de] are compared with the observed flux distribution curves of stars of few spectral classes [Straižys V., Sviderskienė Z., 1972]. It was shown, that just the atmospheric models of hotter stars (Teff > 5000 °K) predict the observed energy distribution quite well. The observations in the GAIA photometric system simulated by Barcelona group are classified using the method of comparison of the color indices of standard and investigated stars. The observations of stars of two magnitudes (G=15 mag and G=18 mag) in the C1M photometric system are investigated in more detail. The analysis of the results shows that the classification is more definite when the bank of more solid standards is used. The errors of classification are smaller for the hotter (Teff > 10000 °K) and more luminous (G=15 mag) stars. The interstellar extinction AV is defined more precisely for hotter stars and the stars with larger AV value (3 ≤ AV ≤ 5). The computing time necessary to classify one star using the method of comparison of the color indices of standard and investigated stars is measured . The classification algorithm is written in PERL. The time is 2.53s / star with the standard bank of 7743 stars and 13 color indices, calculating with 2GFLOPS processor. Though in March, 2006 GAIA design was changed and the photometric system was replaced by spectrographs, the classification algorithm used in the research can be used for GAIA spectra that are being modeled currently.
Internet: https://hdl.handle.net/20.500.12259/117551
Affiliation(s): Švietimo akademija
Vytauto Didžiojo universitetas
Appears in Collections:VDU, ASU ir LEU iki / until 2018

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