Multi-spectral study of a new sample of Blue Compact Dwarf Galaxies

Abstract

Abstract. We present the results of surface photometry on a new sample of Blue Compact Dwarf galaxies (BCDGs), in continuation to a previous paper (Doublier et al. 1997, hereafter Paper I). The 22 galaxies (plus two companions) discussed in the present paper have been selected in the Southern Hemisphere, from several lists. An atlas containing isophotal maps, surface brightnesses and B − R color profiles of the sample is given, together with the tables containing the photometric parameters.The results are consistent with those obtained in Paper I for objects selected from the Byurakan Surveys in the Northern hemisphere. Similarly, we find about one fourth of the BCDGs showing a dominant r 1/4 brightness distribution component, one fourth of the BCDG showing a dominant exponential surface brightness profile, and about half of them show composite brightness distributions. Integrated properties, colors, mean surface brightnesses and luminosity-radius relations are investigated and discussed for the objects presented in this paper and Paper I. We found that r 1/4 BCDGs tend to show a different behaviour compared to the exponential BCDGs, with respect to colors, compactness and luminosity-radius relations. We also include a brief study of the surroundings of the galaxies, where we find several candidate companions.Key words: galaxies: compact -galaxies: photometrygalaxies: starburst -galaxies: structure Send offprint requests to: V. Doublier Based on observations collected at the 1.54 m Danish Telscope at the European Southern observatory (La Silla, Chile).

Deep multiband surface photometry on a sample of 24 blue compact galaxies

“…Originally thought to be tidally interacting with UM462 (Taylor et al 1995), this was later questioned by van Zee et al (1998) who find a crossing time of ∼700 Myr, which is significantly longer than the age of the starburst, expected to be less than 100 Myr. Doublier et al (1999) observe a double exponential profile, with the outer disk visible in the surface brightness profile beyond µ B = 26.75 mag arcsec −2 . However, our B data show no evidence of a double exponential structure around or beyond this isophotal level.…”

“…In fact, the surface brightness profile is very well fitted with a single disk down to µ B ∼ 28 mag arcsec −2 . Since our data are deeper and have much smaller errors at fainter isophotes, the double disk structure in the surface brightness profile of Doublier et al (1999) must be due to systematic sky effects, and not to the presence of a second component. This is consistent with Lagos et al (2011) who also find a single exponential for the host of this galaxy.…”

The Evolutionary Status of Isolated Dwarf Irregular Galaxies. II. Star Formation Histories and Gas Depletion

“…In a starburst model, a region of the stellar disk "" turns on ÏÏ simultaneously with a very high rate of star formation while the remainder of the disk (usually the outskirts) remains quiescent. This centralized star formation activity will result in a radial color gradient in starbursting systems (as observed by, e.g., Papaderos et al 1996 ; Marlowe et al 1997 ; Marlowe, Meurer, & Heckman 1999 ;Doublier et al 1997 ;Doublier, Caulet, & Comte 1999). In contrast, a low level of star formation activity that percolates across the disk in a random manner will result in minor local color variations but no large-scale color gradient, provided that there is no favored location within the disk.…”

Spectroscopic study of blue compact galaxies

“…Much work has been devoted to the study of BCGs, including image (such as Kunth et al 1988;Doublier et al 1999;Cairós et al 2001), and spectra (such as Kunth & Sargent 1979;Terlevich et al 1991;Kinney et al 1993;Kunth et al 1997) observation in all wavelengths. These galaxies have an average surface brightness higher than 20 mag arcsec −2 (Gordon & Gottesman 1981), and are characterized by their compact morphology and blue rest-frame colors (B − V < 0.45, B − r < 0.6; Pisano et al 2001).…”

“…The abundances of heavy elements in these galaxies range between Z /50 and Z /2, and put them among the least chemically evolved galaxies in the universe. The two most metal-deficient galaxies known, I Zw 18 (Z /50) and SBS 0335-052 (Z /41) are BCGs (Doublier et al 1999;Izotov & Thuan 1999). These properties make BCGs represent an extreme environment for star formation, that differs from that in the Milky Way and in many other nearby galaxies.…”