Photometric studies of starburst galaxies

Abstract

We present the results of a detailed morphological analysis of a sample of Markarian starburst galaxies. CCD surface photometry of those galaxies was carried out based on observations made in U BV RI and H?. The morphology of the sample objects was studied using isophotal contours and colour images. The radial variations of the surface brightness, ellipticity, position angle and the colour profiles were constructed using ellipse fitting techniques. We find that the star formation activity is not confined to the central region alone, but it also occurs at various other locations like the ends of bars, along circum-nuclear rings or even globally in a few cases. The luminosity profiles show an exponential nature in the outer region. Strong isophotal twisting is observed in almost all the S0 galaxies in our sample. In a few cases, this is accompanied by boxiness, indicating a strong interaction or merger. Blue light is more centrally concentrated as compared to red light in early type galaxies while the reverse holds for spirals. The scale lengths in B and R are comparable. Composite models were constructed and ages between 106 and 107 years and burst strength between 1% to 5% were able to explain the observed colours.