Observations with the parking lot camera. I - Surface photometry and color distribution of the Magellanic Clouds

Abstract

view Abstract Citations (121) References (23) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations with the Parking Lot Camera. I. Surface Photometry and Color Distribution of the Magellanic Clouds Bothun, Gregory D. ; Thompson, Ian B. Abstract We have obtained B, V, and R CCD images of the SMC and LMC using an optical system that yields a field size of 6^deg^ x 10^deg^. These data allow for the study of the integrated-light and color distributions for both galaxies. From these distributions, we find that the SMC shows a coherent, connected pattern of current (or very recent) star formation and has overall properties like those of star-forming dwarf elliptical galaxies in the Virgo Cluster. In contrast, the LMC exhibits a largely random pattern of star formation, although some hierarchical clustering of different age (color) regions is evident and there is a suggestion in the data that star formation is migrating outwards from the bar region. Neither galaxy, however, shows much evidence for a globally large star-formation rate (e.g., a burst) at the present epoch since (1) they exhibit nominal (~B=21.5 mag arcsec^-2^) central surface brightnesses and (2) their overall colors are significantly redder than those typically measured for other Type I irregular galaxies (e.g., NGC 2366, NGC 4449). The distribution of light in the outermost regions of the SMC falls off exponentially, but there is a conspicuous excess of light in the inner regions due to current star formation. The blue-light distribution in the inner regions of the LMC is well fit by an exponential of scale length 1.5 kpc, which is quite large for a galaxy that does not exhibit obvious spiral structure. Furthermore, this luminosity profile shows a substantial deficit of light, relative to the exponential extrapolation, beginning at 1.65 scale lengths. If the mass distribution of the LMC was once exponential in form, then our data suggest that beyond the 1/2 mass radius, approximately 30% of this mass has been removed. If this mass were still intact, we predict a B = 25.0 mag arcsec^-2^ diameter of 11.2^deg^, similar to the diameter defined by the outermost clusters of the LMC. Finally, we find values for integrated colors and isophotal sizes of the clouds that agree to within 10% of those derived 30 yr earlier by de Vaucouleurs on the basis of photographic photometry. Publication: The Astronomical Journal Pub Date: September 1988 DOI: 10.1086/114854 Bibcode: 1988AJ.....96..877B Keywords: Astronomical Photometry; Dwarf Galaxies; Elliptical Galaxies; Magellanic Clouds; Star Formation Rate; Brightness Distribution; Charge Coupled Devices; Irregular Galaxies; Mass Distribution; Stellar Color; Virgo Galactic Cluster; Astronomy; GALAXIES: MAGELLANIC CLOUDS; GALAXIES: PHOTOMETRY; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (7) NED (2)