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3rd of November 2017
Tidal origin of NGC 1427A in the Fornax cluster
by Karen Lee-Waddell (CASS)
Lee-Waddell et al. (2017) analyse new HI observations from the Australia Telescope Compact Array (ATCA) and deep optical imaging from OmegaCam on the VLT Survey Telescope (VST) of NGC 1427A, an arrow-shaped dwarf irregular galaxy located in the Fornax cluster. The data reveal a star-less HI tail that contains ~10% of the atomic gas of NGC 1427A that sheds new light on the recent history of this galaxy. Rather than being the result of ram pressure induced star-formation, as previously suggested in the literature, the disturbed optical appearance of NGC 1427A has tidal origins.

Figure caption: a) VST r'-band image of central region of the Fornax cluster. Prominent cluster members are indicated by name and bright foreground stars are denoted by the white crosses. b) ATCA total intensity HI (moment-0) contours superimposed on a VST g'r'i'-band composite image of NGC 1427A. The HI tail is the gaseous feature extending towards the southeast (i.e. bottom left of the image). The yellow arrow points to the centre of the Fornax cluster and indicates a likely direct of travel for this galaxy. c) ATCA HI velocity (moment-1) map of NGC 1427A.

Reference: K. Lee-Waddell, P. Serra, B. Koribalski, A. Venhola, E. Iodice, B. Catinella, L. Cortese, R. Peletier, A. Popping, O. Keenan, M. Capaccioli 2017, MNRAS, in press (arXiv:1710.09947)

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