An HII galaxy is a very luminous dwarf starburst galaxy. Generally, HII galaxies have a low metallicity and high percentage of neutral hydrogen. There is generally believed to be a relationship between luminosity and disturbed morphology, suggesting that the starburst activity in the galaxy is caused by tidal interactions.[1] The distribution of luminosities tends to cluster around two different extremes: those with a high luminosity and highly disturbed morphology, and those with a low luminosity and fairly regular and symmetric morphology.[2] Those with high luminosities are labelled by some as type I HII galaxies and those with lower luminosities as type II HII galaxies. There is also a general correlation between metallicity and mass of the galaxies.[3] The name of HII galaxies comes from their spectroscopic properties which are more or less indistinguishable from that of HII regions.[2]

References

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  1. ^ Telles, Eduardo; Terlevich, Roberto (1995-07-01). "The environment of HII galaxies". Monthly Notices of the Royal Astronomical Society. 275 (1): 1–8. arXiv:astro-ph/9501084. doi:10.1093/mnras/275.1.1. ISSN 0035-8711.
  2. ^ a b Telles, Eduardo; Melnick, Jorge; Terlevich, Roberto (1997-06-11). "The morphology of H II galaxies". Monthly Notices of the Royal Astronomical Society. 288 (1): 78–107. arXiv:astro-ph/9701062. doi:10.1093/mnras/288.1.78. ISSN 0035-8711.
  3. ^ Maza, J.; Ruiz, M. T.; Pena, M.; Gonzalez, L. E.; Wischnjewsky, M. (1991). "1991A&AS...89..389M Page 389". Astronomy and Astrophysics Supplement Series. 89: 389. Bibcode:1991A&AS...89..389M. Retrieved 2020-04-11.