If dwarf galaxies are primeval objects in the universe, as hierarchical galaxy formation scenarios predict, they should show traces of their old stellar populations, perhaps distributed in extended, differentiated structures. The working hypothesis that such a structure could exist is tested for the case of DDO 187, a field, dwarf irregular galaxy

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We report high-sensitivity millimeter-wave CO observations of recently discovered bipolar planetary nebulae (PNe). Three objects (BV 5-1, K 3-94 and K 3-24) have been detected, and one of them (BV 5-1) is resolved by the ~ 10{''} telescope beam. The envelopes of the three newly detected objects display values of the molecular to ionized mass ratio

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An absolute calibration of the DENIS photometric system is presented. It includes the determination of the overall transmission profiles in the 3 bands, namely i, J and K_s, combining contributions from atmosphere, telescope mirrors, instrument lenses and dichroics, filters, and detectors. From these normalized profiles, isophotal and effective

We present a detailed study of the bar fraction in the CfA sample of Seyfert galaxies and in a carefully selected control sample of nonactive galaxies to investigate the relation between the presence of bars and of nuclear activity. To avoid the problems related to bar classification in the Third Reference Catalogue (RC3), e.g., subjectivity, low