NGC 2146's starburst region and extended structure

¹ IRAM, 300 rue de la Piscine, 38406 St.-Martin-d'Hères, France e-mail: greve@iram.fr
² Astronomisches Institut der Universität Bonn, 71 Auf dem Hügel, 53121 Bonn, Germany
³ IRAM, Nucleo Central, 7 Avenida Divina Pastora, 18012 Granada, Spain
⁴ INAF – Instituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
⁵ INAF – Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra (CA), Italy

Received: 24 June 2005
Accepted: 26 July 2006

Abstract

We present mm-wavelength and optical observations of the starburst region in NGC 2146. This region of ~4 kpc diameter contains a well-ordered distribution of stars, gas, and dust, and a well-ordered rotation. The possible anomalies found in our observation are a warped CO distribution and an increase in the CO line width at the NW edge of the starburst region. The investigation of a possible encounter or merger origin of the starburst may therefore have to concentrate on the distorted outer structure of the galaxy. There are three large-scale features of ~20 kpc extent, two of which give the impression of being stellar sub-systems. The third feature is an incomplete and expanding ring of H ii regions and stars, apparently indicating an event that occurred some 300 Myr ago.