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26th of February 2018
Gemini Follow-up of Two Massive HI Clouds Discovered with ASKAP
by Juan Madrid
Using the Gemini Multi Object Spectrograph (GMOS), Madrid et al. searched for optical counterparts of two massive (∼a billion solar masses) neutral hydrogen clouds near the spiral galaxy IC 5270, located in the outskirts of the IC 1459 group. These two HI clouds were recently discovered using the Australian Square Kilometer Array Pathfinder (ASKAP). Two low surface brightness optical counterparts to one of these HI clouds are identified in the new Gemini data that reaches down to magnitudes of ∼27.5 mag in the g-band. The observed HI mass-to-light ratio derived with these new data, M (HI)/Lg = 242, is among the highest reported to date. The team rule out the possibility that the two H I clouds are dwarf companions of IC 5270. Tidal interactions and ram pressure stripping are plausible explanations for the physical origin of these two clouds. The figure above shows the new Gemini image with ASKAP contours of the two HI clouds located north and north–east of IC 5270. The red boxes show the location of the two optical counterpart candidates.
This work is published in Madrid et al. 2018, Astrophysical Journal, vol. 854, article id. 6

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