New HI Observations of the Prototype Polar Ring Galaxy NGC 4650A

Magda Arnaboldi (MSSSO), Tom Oosterloo (ATNF), Francoise Combes (DEMIRM),
Ken Freeman (MSSSO), Bärbel Koribalski (ATNF)

(1996) AJ 113, 585

Abstract. New, high resolution observations of the H I emission line and 20-cm continuum at the Australia Telescope Compact Array (ATCA) for the prototype polar ring galaxy NGC 4650A are presented. We show the presence of a far more extended HI distribution than previously observed with the VLA, and a very regular velocity field out to a distance of approx. 50 kpc. The combined analysis of the HI data with optical and near infrared images argues against previous warp models used to describe the dynamics of this object. A comparison between the high resolution H I images and a new B-band image obtained at the ESO NTT further weakens the interpretation of the optical morphology via warp geometries. The presence of two spiral arms stretching out in the polar disk seems to represent the most likely explanation for the observed morphology and kinematics.

Keywords. galaxies: individual (NGC 4650A) - galaxies: dynamics - galaxies: dark matter.

  • related paper: Combes & Arnaboldi 1996, A&A 305, 763,
    ``The dark halo of polar-ring galaxy NGC 4650a: flattened towards the polar ring ?''