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The HI content of isolated ultra-diffuse galaxies: A sign of multiple formation mechanisms?
Astronomy & Astrophysics (2017)
  • E. Papastergis, University of Groningen
  • E. A.K. Adams, ASTRON, the Netherlands Institute for Radio Astronomy
  • Aaron J. Romanowsky, San Jose State University
We report on the results of radio observations in the 21 cm emission line of atomic hydrogen (HI) of four relatively isolated ultra-diffuse galaxies (UDGs): DGSAT I, R-127-1, M-161-1, and SECCO-dI-2. Our Effelsberg observations resulted in non-detections for the first three UDGs, and a clear detection for the last. DGSAT I, R-127-1, and M-161-1 are quiescent galaxies with gas fractions that are much lower than those of typical field galaxies of the same stellar mass. On the other hand, SECCO-dI-2 is a star forming gas-rich dwarf, similar to two other field UDGs that have literature HI data: SECCO-dI-1 and UGC 2162. This group of three gas-rich UDGs have stellar and gaseous properties that are compatible with a recently proposed theoretical mechanism for the formation of UDGs, based on feedback-driven outflows. In contrast, the physical characteristics of R-127-1 and M-161-1 are puzzling, given their isolated nature. We interpret this dichotomy in the gaseous properties of field UDGs as a sign of the existence of multiple mechanisms for their formation, with the formation of the quiescent gas-poor UDGs remaining a mystery.
  • galaxies: dwarf,
  • galaxies: formation,
  • galaxies: ISM,
  • galaxies: fundamental parameters
Publication Date
May, 2017
Publisher Statement
This article was originally published in Astronomy & Astrophysics, volume 601. © ESO 2017. All rights reserved.

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Citation Information
E. Papastergis, E. A.K. Adams and Aaron J. Romanowsky. "The HI content of isolated ultra-diffuse galaxies: A sign of multiple formation mechanisms?" Astronomy & Astrophysics Vol. 601 (2017) ISSN: 0004-6361
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