ar X iv : a st ro - p h / 99 02 01 1 v 1 1 F eb 1 99 9 H i in Early - Type Galaxies Tom
نویسندگان
چکیده
We summarize the H i properties of early-type galaxies, in particular the differences in H i morphologies observed in early-type galaxies of different luminosities. We find that in lowluminosity early-type galaxies the H i is almost always in a disk-like structure, with central surface densities high enough for star formation to occur. In a few luminous early-type galaxies the H i is also in a disk or in a ring-like structure, but in most luminous early-type galaxies the H i has a relatively irregular morphology. The surface densities in the H i disks in luminous early-type galaxies are lower than in the H i disks in low-luminosity early-type galaxies and no large-scale star formation should occur in these disks. We discuss these different H i characteristics in the context of other properties of early-type galaxies that correlate with luminosity.
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ar X iv : a st ro - p h / 99 02 06 2 v 1 4 F eb 1 99 9 SOURCES OF RELATIVISTIC JETS IN THE GALAXY
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