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The visible environment of galaxies with counterrotation
In this paper we present a statistical study of the environments of 49galaxies in which there is gas- or stellar-counterrotation. The numberof possible companions in the field (to apparent magnitude 22), theirsize and concentration were considered. All the statistical parameterswere analysed by means of Kolgomorov-Smirnov tests, using a controlsample of 43 galaxies without counterrotation. From our data, nosignificant differences between the counter-rotating and control samplesappear. This is different to Seyfert or radio-loud galaxies which lie inenvironments with a higher density of companions. On the contrary, if aweak tendency exists, for galaxies with gas counterrotation only, it isdiscovered in regions of space where the large scale density of galaxiesis smaller. Our results tend to disprove the hypothesis thatcounterrotation and polar rings derive from a recent interaction with asmall satellite or a galaxy of similar size. To a first approximation,they seem to follow the idea that all galaxies are born through a mergerprocess of smaller objects occurring very early in their life, or thatthey derive from a continuous, non-traumatic infall of gas that formedstars later. Whatever the special machinery is which producescounterrotation or polar rings instead of a co-planar, co-rotatingdistribution of gas and stars, it seems not to be connected to thepresent galaxy density of their environments.
| The Stromlo-APM Redshift Survey. IV. The Redshift Catalog
The Stromlo-APM Redshift Survey consists of 1797 galaxies with b_J_ <17.15 selected randomly at a rate of 1 in 20 from automated platemeasurement (APM) scans. The survey covers a solid angle of 1.3 sr (4300deg^2^) in the south Galactic cap. Redshifts have been measured for 1790(99.6%) of the galaxies. The median galaxy recession velocity is 15,300km s^-1^, and so the volume probed is V ~ 1.38 x 10^6^ h^-3^ Mpc^3^. Inthis paper we describe the construction of the redshift catalog andpresent the survey data.
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