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Astron. Astrophys. 326, 907-914

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The visible environment of polar ring galaxies*

Chiara Brocca1, Daniela Bettoni2, and Giuseppe Galletta1

1Dipartimento di Astronomia, Università di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova, Italy
2Osservatorio Astronomico, Vicolo Osservatorio 5, I-35122 Padova, Italy

Received 17 December 1996 / accepted 22 May 1997


A statistical study of the environment around Polar Ring Galaxies is presented. Two kinds of search are performed: 1) a study of the concentration and diameters of all the objects surrounding the Polar Rings, within a search field 5 times the ring diameter. New magnitudes for polar ring galaxies are presented. 2) a search, in a wider field, for galaxies of similar size that may have encountered the polar ring host galaxy in a time of the order of 1 Gyr. Differently from the results of similar searches in the fields of active galaxies, the environment of the Polar Ring Galaxies seems to be similar to that of normal galaxies.

This result may give support to the models suggesting long times for formation and evolution of the rings. If the rings are old (and stable or in equilibrium), no traces of the past interaction are expected in their surroundings. In addition, the formation of massive polar rings, too big to derive from the ingestion of a present-day dwarf galaxy, may be easily placed in epochs with a higher number of gas-rich galaxies.

Key words: galaxies: evolution - galaxies: formation - galaxies: interactions - galaxies: peculiar

*based on data obtained using the Guide Stars Selection System Astrometric Support Program developed at the Space Telescope Science Institute

Send offprint requests to: D. Bettoni

© European Southern Observatory (ESO) 1997

Online publication: October 1, 1997
Last change: April 8, 1998