The formation of giant cloud complexes by the Parker-Jeans instability

摘要: The Parker-Jeans instability is considered as a possible mechanism for forming the giant cloud complexes observed near OB associations. We use previously derived dispersion relation to evaluate masses and growth times of dominant modes in this instability. results show that massive clouds (Mroughly-equal10/sup 6/ M/sub sun/) can form quickly (roughly-equal12 million yr) high density environments (5 cm/sup -3/) associated with spiral wave shocks. For densities larger than about 3 -3/, these primarily result self-graviational forces interstellar medium. Lower mass 5/ lower pure Parker when exceeds cm /sup -3/ are insensitive magnetic field strength, cosmic ray pressure, ambient (even compressed media.). These essentially Jeans occurrence characteristic may explain similarity local role part complete theory formation summarized.