Extragalactic H2O masers

  • Lincoln J. Greenhill
4. Extragalactic Masers
Part of the Lecture Notes in Physics book series (LNP, volume 412)


Twenty-five extragalactic H2O masers are known, classified as normal masers and megamasers. The first VLBI synthesis images of a normal maser, the one associated with the IC 133 region of M33, as well as observations of its environs, show it to be comparable physically to the most powerful galactic masers. Inference from past observations of megamasers has been that megamasers are intrinsically different than normal masers, arising from uncommon or extreme physical conditions. However, the first ever synthesis images of a megamaser, the one toward the nucleus of NGC 3079, show that this source too is structurally similar to galactic maser sources.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Filippenko, A. V. and Sargent, W. L. W. 1992, A. J., 103, 28Google Scholar
  2. Greenhill, L. J., Moran, J. M., Reid, M. J., Gwinn, C. R., Menten, K. M., Eckart, A., and Hirabayashi, H. 1990, Ap. J., 364, 513Google Scholar
  3. Greenhill, L. J., Moran, J. M., Reid, and Hirabayashi, H. 1992, in preparationGoogle Scholar
  4. Haschick, A. D., Baan, W., Schneps, M. H., Reid, M. J., Moran, J. M., and Güsten, R. 1990, Ap. J., 356, 149Google Scholar
  5. Huchtmeier, W. K., Eckart, A., and Zensus, A. J. 1988, Astr. Ap., 200, 26Google Scholar
  6. Israel, F. P., Hawarden, T. C., Geballe, T. R., Wade, R. 1990, MNRAS, 242, 471Google Scholar
  7. Liljeström, T., Mattila, K., Toriseva, M., and Anttila, R. 1989, Astr. Ap. Suppl., 79, 19Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Lincoln J. Greenhill
    • 1
  1. 1.Deptartment of AstronomyUniversity of CaliforniaBerkeley

Personalised recommendations