Neutral Hydrogen Emission and Galaxies

Neutral Hydrogen (HI) is found in most galaxies. We can detect HI from its 21cm line emission. In a cloud of HI that is dense enough, the interactions between the hydrogen atoms is enough to stimulate the 21cm emission, therefore clouds of HI gas can be detected even when there is no other radiation present (ie: we don't need stars to detect HI).
Spectral Line Group Home Page
Jodrell Bank Home Page

Maintianed by Virginia Kilborn
Last Modified 8 March 2001

Current Research Areas

The main research that is done at Jodrell Bank is a blind survey of the northern sky looking for HI in galaxies. This survey uses a 4 beam multibeam system, which is mounted on the Lovell Telescope. The areas surveyed so far include the +74 declination band, which is a strip of sky 8 degrees wide covering all R.A. We have also surveyed the M82 group, Abell 1367, part of the Virgo cluster, and the intersection of the zone of avoidance with the supergalactic plane.

Types of Galaxies found

Most of the galaxies found so far are normal spiral galaxies, Sb-Sc being the most common. In addition, a number of optically faint, yet HI-rich galaxies have been discovered.

Refereed Publications


  • 'HIPASS Detection of an Intergalactic Gas Cloud in the NGC 2442 Group'
    S. D. Ryder, B. Koribalski, L. Staveley-Smith, V. Kilborn, D. Malin, G. Banks, D. Barnes, R. Bhatal, W. de Blok, P. Boyce, M. Disney, M. Drinkwater, R. Ekers, K. Freeman, B. Gibson, P. Henning, H. Jerjen, P. Knezek, M. Marquarding, R. Minchin, J. Mould, T. Oosterloo, R. Price, M. Putman, E. Sadler, I. Stewart, F. Stootman, R. Webster, and A. Wright, to be published in ApJ, Vol. 555, 1 July 2001.


  • `An Extragalactic H I Cloud with No Optical Counterpart?'
    Kilborn, V. A., Staveley-Smith, L., Marquarding, M., Webster, R. L., Malin, D. F., Banks, G. D., Bhathal, R., de Blok, W. J. G.; Boyce, P. J., Disney, M. J., Drinkwater, M. J., Ekers, R. D.; Freeman, K. C., Gibson, B. K., Henning, P. A., Jerjen, H., Knezek, P. M., Koribalski, B. Minchin, R. F. Mould, J. R. Oosterloo, T. Price, R. M. Putman, M. E. Ryder, S. D. Sadler, E. M. Stewart, I. Stootman, F. Wright, A. E., AJ 2000, 120, 1342


  • `New Galaxies Discovered in the First Blind H I Survey of the Centaurus A Group'
    Banks, G. D.; Disney, M. J.; Knezek, P. M.; Jerjen, H.; Barnes, D. G.; Bhatal, R., de Blok, W. J. G.; Boyce, P. J.; Ekers, R. D.,Freeman, K. C.; Gibson, B. K., Henning, P. A.; Kilborn, V.; Koribalski, B., Kraan-Korteweg, R. C.; Malin, D. F., Minchin, R. F.; Mould, J. R.; Oosterloo, T.; Price, R. M., Putman, M. E.; Ryder, S. D., Sadler, E. M., Staveley-Smith, L.; Stewart, I., Stootman, F.; Vaile, R. A.; Webster, R. L., Wright, A. E., ApJ 1999, 524, 612

  • `HI mass function from HIPASS'
    Kilborn, V., Webster, R. and Staveley-Smith, L., PASA 1999, 16, 8


  • `Tidal disruption of the Magellanic Clouds by the Milky Way.'
    Putman, M. E., Gibson, B. K., Staveley-Smith, L., Banks, G., Barnes, D. G., Bhatal, R., Disney, M. J., Ekers, R. D., Freeman, K. C., Haynes, R. F., Henning, P., Jerjen, H., Kilborn, V., Koribalski, B., Knezek, P., Malin, D. F., Mould, J. R., Oosterloo, T., Price, R. M., Ryder, S. D., Sadler, E. M., Stewart, I., Stootman, F., Vaile, R. A., Webster, R. L., Wright, A. E., Nature, 1998, 394, 752


The following links are to observatories that conduct research in neutral hydrogen, or HI research projects.
  • HIPASS Home Page - The southern all-sky survey, conducted at the Parkes Radio-Telescope in Australia.

  • ATNF - Home page of the Australia Telescope National Facility.

  • WRST - Westerbork Synthesis Radio Telescope.

  • NRAO - The American National Radio Astronomy Observatory. This include the Green Bank Telescope, and the Very Large Array (VLA).