Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interaction of massive stars with their surroundings   Due to their short lifetimes but their enormous energy release in all stages
of their lives massive stars are the major engines for the comic matter
circuit. They affect not only their close environment but are also responsible
to drive mass flows on galactic scales. Recent 2D models of radiation-driven
and wind-blown HII regions are summarized which explore the impact of massive
stars to the interstellar medium but find surprisingly small energy transfer
efficiencies while an observable Carbon self-enrichment in the Wolf-Rayet phase
is detected in the warm ionized gas. Finally, the focus is set on
state-of-the-art modelling of HII regions and its present weaknesses with
respect to uncertainties and simplifications but on a perspective of the
requested art of their modelling in the 21st century.

37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th