A Comprehensive Study of the Peculiar Spiral Galaxy NGC 1808

Bärbel Koribalski (MPIfR Bonn and Uni Bonn),
Michael Dahlem (MPIfR Bonn and Uni Bonn), Ulrich Mebold (Uni Bonn), Elias Brinks (NRAO)

(1993) A&A 268, 14

Abstract. Here we report results of HI line observations if the starburst galaxy NGC 1808 with the Very Large Array (VLA) in its CnD hybrid configuration. The analysis of the global HI distribution and the velocity field revealed new details in the kinematics of this peculiar galaxy. We find 1) the clear signature of a warp in the outer gas layer, and 2) outflow of neutral hydrogen gas from the nuclear region. The warp has been deduced from the near-circular shape of the HI gas distribution (diameter approx. 10 arcmin > optical size) which is in contrast to the ellipticity of the disk. Through a `tilted-ring model' fit we derive a warp angle of about 23 degrees. In the northeastern part of the disk, where prominent dust filaments seem to emerge from the nuclear region, we find a velocity anomaly which indicates outflow of HI gas into the halo of the galaxy. This means that we determined the flow direction of the dust filaments which have long been known from optical observations. Finally we discuss the possibility that the warp and the outflow of gas have been caused by interactions with the neighbour galaxy NGC 1792.

Keywords. galaxies: general - galaxies: spiral - galaxies: NGC 1808 - galaxies: kinematics and dynamics of - radio lines: 21 cm

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Bärbel Koribalski * Baerbel.Koribalski @ csiro.au