Earth & Solar System

Geocoronal Studies 

Unfortunately for Galactic observers, the earth provides it's own Hα and Hβ emission line which varies with time and location on the sky. However, this emission is precisely the interest of a group of Wisconsin and Embry-Riddle aeronomers. In collaboration with Susan Nossal, Ed Mierkiewicz, and Fred Roesler, nearly every photon collected for the WHAM all-sky survey is being used for scientific research. WHAM observations of the geocoronal line are helping to shape models of the earth's exosphere, the very outer reaches of our atmosphere.

Lunar Sodium

Smith and collaborators (Smith et al. 2001, 1999) discovered an extended tail of lunar sodium atoms over 400,000 km long with an all-sky imaging device. Several processes may be responsible for this atmosphere including thermal desorption, photo-desorption, ion sputtering and meteoric impact ablation. However, the relative importance of these processes remains uncertain, both with regard to spatial and temporal trends. Collaborators Ed Mierkiewicz and Michael Line used WHAM to map morphology and velocity distribution of this extended lunar sodium exosphere (Line et al. 2012). When compared to models, these spectral observations can be used to infer the initial velocity distribution of the sodium atoms escaping from the moon.

Comets

Hyakutake: In collaboration with Frank Scherb and Fred Roesler the WHAM group collected [O I] 6300Å, Hα, Hβ, and NH2 data in March and April of 1996 during the close passage of the comet. The [O I] data provided a sensitive measurement of the water production rate in the comet. The Hβ data revealed the first detection of this line from a comet and, combined with the Hα data, provide interesting information on the solar Lyβ emission line and how it affects the comet.

Hale-Bopp: This spectacular comet was also observed by WHAM in February - April of 1997. The [O I] distribution around the comet was mapped out to explore water production rates. The water ion, H2O+, was also observed this time, and provides a sensitive tracer of the comet's ion tail. Using WHAM's extremely narrow-band imaging mode (~12 km/s passband), we obtained a data cube of velocity slices, which may provide detailed information about the motion of ions down the comet's tail.


Publications

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