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Galactic Latitude (Deg.)

Fig 16.13.

Thickness of the plane as measure by four tracers. In general, components that are more concentrated to the plane are thought of as being younger, in the sense that they have not had as much time to spread out. [Eli Dwek, NASA/Sodroski,T. et al., Astrophys.J., 322, 101, 1987]

Galactic Latitude (Deg.)

Fig 16.13.

Thickness of the plane as measure by four tracers. In general, components that are more concentrated to the plane are thought of as being younger, in the sense that they have not had as much time to spread out. [Eli Dwek, NASA/Sodroski,T. et al., Astrophys.J., 322, 101, 1987]

thickness of the plane in H2 is about half that in HI. We have seen that one feature of population I material is its confinement to the galactic plane. We therefore think of molecular clouds as representing a more extreme population I than that represented by the HI clouds. This might indicate that molecular clouds, as a whole, are more recently formed than the HI clouds. Finally, the H2 shows the same flaring and warp as the HI.

Additional information on the total gas distribution (HI plus H2) comes from observations of gamma-rays. These gamma-rays are created when cosmic rays strike protons. It doesn't matter what types of atoms or molecules the protons are in. The results are somewhat uncertain, but provide an additional constraint. The general conclusion from such observations supports the conclusions from the CO observations.

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