LMC & SMC
We will be mapping emission in and around these nearby neighbors to see how far their ionized gas extends. The kinematics revealed by these spectral observations may uncover some surprises and should allow us to study connections between the neutral gas in and around the galaxies and any extended ionized structures. WHAM's one-degree beam is too large to provide a great amount of insight on the internal structure of the galaxies themselves.
21 cm observations have shown that a tenuous neutral structure connects the galaxies. Some ionized material and even early stars suggestive of recent star formation has been detected in the portion of the Bridge closest to the SMC. With WHAM, we will be able to detect and map any ionized gas associated with this feature to very faint emission measures.
An impressive, ~100°-long tail of gas trails the clouds' orbit through the Milky Way's halo. Prior studies have shown there is both ionized gas and Hα emission at certain locations along the Stream, but the full structure has only been surveyed in H I to date. One of our major priorities from Chile is to provide the first survey of the Stream in Hα and to carry out several comprehensive multiline studies along its length. There are many outstanding questions about the origin of the Stream and its evolution, dominant gas phases, ionization structure, and interaction with the halo of the Milky Way.
Out ahead of the galaxies' orbit, a less organized collection of neutral gas proceed their passage through the halo. No ionized emission has been detected from this structure yet, but WHAM should provide the most sensitive search to date.
Barger, K., Haffner, L., Bland-Hawthorn, J., 2013
The Astrophysical Journal, Vol. 771, Pages 132
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