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Abstract:
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In this dissertation we discuss in
uence of H emission from supernova remnants
(SNRs) on H derived star formation rates (SFRs). We present the detection of 16
optical SNR candidates in a part of nearby spiral galaxy IC342, and two more poten-
tial SNRs in NGC 185 galaxy. The candidates were detected by applying [S ii]/H
ratio criterion on observations made with the 2 m telescope at Rozhen National
Astronomical Observatory in Bulgaria. Also, in this dissertation we present the
most up-to-date list of nearby galaxies with optically detected SNRs. When deri-
ving H star formation rates, assumption is that the radiation is coming from the
ionized gas surrounding hot and young stars { Hii regions. In this case, emission
from SNRs contaminates H
ux used to derive SFR. We found that the contribu-
tion of SNRs'
ux to the total H
ux, for 18 galaxies in our sample of galaxies
with optical SNRs, is 5 5%. Due to the observational selection effects, the SNR
contamination of SFRs derived herein represents only a lower limit. M83 is the
galaxy with the most detected optical SNRs and in this galaxy SNRs account for
9 per cent of the total H emission. We expect that fraction similar to this would
be close to the real contribution of SNR emission to the total H emission in spiral
galaxies.
Using two dwarf galaxies as an example, Holmberg IX and NGC 185, we show
that the contamination of H
ux by SNRs, or other sources, can be much larger,
up to ten times higher than total H
ux coming from Hii regions of the observed
galaxy. |