NGC 55
NGC 55 (HIPASS J0015-39)
is a Magellanic barred spiral galaxy in the Sculptor Group, viewed nearly
edge-on, with a stellar diameter of at least half a degree, located ~8 degr
(300 kpc) from NGC 300. Both galaxies and their large-scale surroundings were
recently mosaicked in HI with the ATCA by Westmeier et al. (2011, 2013) who
used 32 pointings covering an area of about 2 degr x 2 degr to reveal much
larger gas envelopes than previously known. They also found disturbed outer
disc gas in both galaxies as well as high-velocity clouds (HVCs) surrounding
NGC 55. We refer to Westmeier et al. for a detailed analysis and literature
overview of both Sculptor galaxies.
The large galaxies NGC 55 and NGC 300,
together with the dwarf galaxies ESO 294-G010,
ESO 410-G005,
UGCA 438 and IC 5152 (all detected in HI)
form a small subgroup at the near side of the Sculptor Group at a distance of
~2 Mpc.
The ATCA HI distribution of the edge-on spiral NGC 55 is quite
asymmetric, with the neutral gas more extended towards the east (receding
side) and north. Contours in the west and south are much more
compressed suggesting the influence of ram pressure stripping. The twisting
of the HI velocity contours hints at a mild warp of the outer disc
(Westmeier et al. 2013). Star formation is prominent in the disc, possibly
responsible for extraplanar HII regions (Tüllmann et al. 2003).
Reference:
Koribalski et al. 2018
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