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Astron. Astrophys. 357, L1-L4 (2000)

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Letter to the Editor

Cut-off radii of galactic disks

A new statistical study on the truncation of galactic disks  *

M. Pohlen, R.-J. Dettmar and R. Lütticke

Ruhr-Universität Bochum, Astronomisches Institut, 44780 Bochum, Germany (pohlen,dettmar,luett@astro.ruhr-uni-bochum.de)

Received 13 September 1999 / Accepted 22 March 2000


We present the analysis of a CCD survey of 31 nearby ([FORMULA] 110 Mpc) edge-on spiral galaxies. The three-dimensional one-component best fit models provide their disk-scalelengths h and for the first time their disk cut-off radii [FORMULA]. We confirm for this sample the existence of such sharp truncations, and find a significantly lower mean value of the distance independent ratio [FORMULA] than the standard value of 4.5 often used in the literature. Our data show no correlation of these parameters with Hubble type, whereas we report a correlation between [FORMULA] and the distance based scalelength in linear units. Compared to the Milky Way we find only lower values of [FORMULA], explained either by possible selection effects or by the completely different techniques used. We discuss our data in respect to present models for the origin of the cut-off radii, either as a relict of the galaxy formation process, or as an evolutionary phenomenon.

Key words: galaxies: evolution – galaxies: formation – galaxies: fundamental parameters – galaxies: photometry – galaxies: structure – galaxies: spiral

* Based on observations collected at the European Southern Observatory, Chile and Lowell Observatory, Flagstaff (AZ), USA

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© European Southern Observatory (ESO) 2000

Online publication: May 3, 2000