Grand-design spirals in the core of NGC 5248

Abstract

We report the detection of a bisymmetric nuclear spiral structure in the spiral galaxy NGC 5248.The two red spiral arms can be followed for about 3 arcsec, before they appear to end inside the radius of the circumnuclear starburst `ring' at about 5.5 arcsec or 400 pc distance from the nucleus. We combine our near-infrared Canada–France–Hawaii Telescope adaptive optics images with traditional near-infrared and optical images and show that spiral structure is present in this galaxy at spatial scales reaching from a hundred parsecs to 15 kpc. Comparison with a Hubble Space Telescope ultraviolet image shows how the starburst ring is related to the nuclear spiral structure. We also show a two-dimensional Hα velocity field that reveals no evidence for systematic streaming motions near the nuclear spiral or the starburst ring, nor for a rapidly rising rotation curve.