Dr Greg Madsen (Anglo Australian Observatory)

Recent Results from the Wisconsin H-Alpha Mapper - Dr Greg Madsen Colloquium

ATNF Marsfield Lecture Theatre

Abstract

We discuss recent results from the Wisconsin H-Alpha Mapper (WHAM).
WHAM is a remotely operated, dual-etalon Fabry-Perot spectrometer at
Kitt Peak that is designed to study and detect faint, diffuse optical
emission. WHAM's unprecedented sensitivity and spectral resolution
have been used to pursue a wide range of scientific interests. The
primary mission is an all-sky survey of H-alpha emission, which is now
complete. This survey has provided the first velocity resolved maps of
the distribution and kinematics of ionized gas in the Galaxy,
comparable to all-sky surveys of neutral hydrogen. WHAM has
characterized the layer of widespread diffuse ionized gas that pervades
that Galaxy, known as the warm ionized medium (WIM).

In this talk, I will concentrate on new observations of multiple
emission lines, including [NII], [SII], and [OIII], toward a variety
of H-alpha emitting structures revealed by the survey. These
observations are combined with the H-alpha data to constrain the
physical conditions of the WIM. We find significant differences in the
temperature and ionization state of this diffuse ionized gas compared
to classical HII regions. These results have important implications for
the nature and origin of the WIM.

I will conclude by discussing briefly some of the other current and
future projects with WHAM. These include an investigation of an optical
window into the inner Galaxy, the detection of H-alpha emission from
high-velocity clouds, a search for ionized gas in dwarf spheroidal
galaxies, a study of the kinematics of zodiacal dust, and the potential
for a WHAM-South in Australia.