Abstract: The molecular gas of the interstellar
medium provides the raw material for star formation, yet its principle
component – molecular hydrogen – is essentially invisible at radio
wavelengths. Instead, we must infer its presence and properties
through the study of other tracer molecules, such as hydroxyl
(OH). OH, with its four ground-rotational transitions at 1612, 1665,
1667 and 1720 MHz is a challenging molecule to observe due both to the
weakness of its lines and the complexity of their excitation. However,
the complex excitation of OH holds valuable information about the host
molecular gas. The satellite lines at 1612 and 1720 MHz in particular,
with their ubiquitous anomalous excitation, are much more sensitive to
local conditions than the main lines which rarely diverge from their
expected excitation at local thermodynamic equilibrium (LTE). In this
talk, I will discuss my PhD research which focused on exploring the
utility of this interesting molecule. I will also introduce my current
project which is to monitor the time-variability of high-gain OH
masers in star-forming regions.
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