Possible relationship between ring magnetism and H I gas in spiral galaxies

Polarization observations of spiral galaxies have revealed so far only two types of large-scale distribution for their magnetic fields, either mostly ring shaped or mostly spiral shaped. A newly found relationship is reported here, namely: the observation of ring magnetism in the presence of a ''large'' quantity of H I gas mass, and the observation of spiral magnetism in the presence of a ''small'' quantity of H I gas mass. A previously known relationship is strengthened here, namely: the observation of spiral magnetism in the presence of a large tidal interaction with a companion galaxy, and the observation of ring magnetism in the presence of a small tidal interaction. Both relationships appear to be physically reasonable, and complementary