  With an aim of probing the physical conditions and excitation mechanisms of
warm molecular gas in individual star-forming regions, we performed Herschel
SPIRE FTS observations of 30 Doradus in the LMC. In our FTS observations,
important FIR cooling lines in the ISM, including CO J=4-3 to 13-12, [CI] 370
micron, and [NII] 205 micron, were clearly detected. In combination with
ground-based CO data, we then constructed CO spectral line energy distributions
(SLEDs) on 10 pc scales over a 60 pc x 60 pc area and found that the shape of
the observed CO SLEDs considerably changes across 30 Doradus, e.g., the peak
transition varies from J=6-5 to 10-9, while the slope characterized by the
high-to-intermediate J ratio ranges from 0.4 to 1.8. To examine the source(s)
of these variations in CO transitions, we analyzed the CO observations, along
with [CII] 158 micron, [CI] 370 micron, [OI] 145 micron, H2 0-0 S(3), and FIR
luminosity data, using state-of-the-art models of PDRs and shocks. Our detailed
modeling showed that the observed CO emission likely originates from
highly-compressed (thermal pressure ~ 1e7-1e9 K cm-3) clumps on 0.7-2 pc
scales, which could be produced by either UV photons (UV radiation field ~
1e3-1e5 Mathis fields) or low-velocity C-type shocks (pre-shock medium density
~ 1e4-1e6 cm-3 and shock velocity ~ 5-10 km s-1). Considering the stellar
content in 30 Doradus, however, we tentatively excluded the stellar origin of
CO excitation and concluded that low-velocity shocks driven by kpc scale
processes (e.g., interaction between the Milky Way and the Magellanic Clouds)
are likely the dominant source of heating for CO. The shocked CO-bright medium
was then found to be warm (temperature ~ 100-500 K) and surrounded by a
UV-regulated low pressure component (a few (1e4-1e5) K cm-3) that is bright in
[CII] 158 micron, [CI] 370 micron, [OI] 145 micron, and FIR dust continuum
emission.
