Researchers discover UGC 3672 galaxy to be an unusual merging triplet of gas-rich dwarf galaxies November 8, 2016 by Tomasz Nowakowski report Please Register or Log in to view the hidden image! Left: An overlay of the Hi velocity field at 8.′′1 × 5.′′5 (contours) on the KPNO 0.9m B-band image of UGC 3672A. The overall North-South extent of the very low surface brightness optical emission is ∼40′′. A faint foreground star is also seen superposed on the diffuse optical emission. A change in the direction of the gradient of the Hi velocity field around U3672A can also be seen. Right: An greyscale representation of the second moment of the Hi distribution at 8.′′1 × 5.′′5. The beam size is shown in the lower left corner. An increase in the velocity dispersion around U3672A can be seen. Credit: Chengalur et al., 2016. (Phys.org)—Astronomers from India and Russia revealed new information about the composition of the galaxy UGC 3672. According to a paper published Nov. 4 on the arXiv pre-print server, UGC 3672 is actually a triplet of very gas-rich dwarf galaxies in the process of merging. Read more at: http://phys.org/news/2016-11-ugc-galaxy-unusual-merging-triplet.html#jCp
https://arxiv.org/pdf/1611.01271v1.pdf UGC 3672: An unusual merging triplet of gas-rich galaxies in the Lynx-Cancer void ABSTRACT: We present Hi 21cm and optical observations of UGC 3672 which is located near the centre of the nearby Lynx-Cancer void. We find that UGC 3672 consists of an approximately linearly aligned triplet of gas rich dwarfs with large scale velocity continuity along the triplet axis. The faintest component of the triplet is extremely gasrich MHI/LB ∼ 17) and also extremely metal deficient (12 + log(O/H) ∼ 7.0). The metallicity of this dwarf is close to the ’floor’ observed in star forming galaxies. Low resolution Hi images show that the galaxy triplet is located inside a common Hi envelope, with fairly regular, disk like kinematics. At high angular resolution however, the gas is found to be confined to several filamentary tidal tails and bridges. The linear alignment of the galaxies, along with the velocity continuity that we observe, is consistent with the galaxies lying along a filament. We argue that the location of this highly unusual system in an extremely low density environment is not a coincidence, but is a consequence of structure formation proceeding more slowly and also probing smaller scales than in regions with average density. Our observations also indicate that wet mergers of galaxies flowing along filaments is a possible pathway for the formation of gas rich disks. The UGC 3672 system provides an interesting opportunity to study the kind of interactions typical between high redshift extremely gas rich unevolved small systems that lie at base of the hierarchical galaxy formation model.
