Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Physical Properties of Red Supergiants   Red supergiants (RSGs) are an evolved He-burning phase in the lifetimes of
moderately high mass (10 - 25 solar mass) stars. The physical properties of
these stars mark them as an important and extreme stage of massive stellar
evolution, but determining these properties has been a struggle for many years.
The cool extended atmospheres of RSGs place them in an extreme position on the
Hertzsprung-Russell diagram and present a significant challenge to the
conventional assumptions of stellar atmosphere models. The dusty circumstellar
environments of these stars can potentially complicate the determination of
their physical properties, and unusual RSGs in the Milky Way and neighboring
galaxies present a suite of enigmatic properties and behaviors that strain, and
sometimes even defy, the predictions of stellar evolutionary theory. However,
in recent years our understanding of RSGs, including the models and methods
applied to our observations and interpretations of these stars, has changed and
grown dramatically. This review looks back at some of the latest work that has
progressed our understanding of RSGs, and considers the many new questions
posed by our ever-evolving picture of these cool massive stars.

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The categories of this paper are: physics
11
The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
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The categories of this paper are: math
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: plasm-ph