Stars as Laboratories for Fundamental Physics - MPP Theory Group

Chapter 2
Anomalous
Stellar Energy Losses
Bounded by Observations
After a description of the main phases of stellar evolution, a review is
given of the observations that have been used to constrain novel stellar
energy losses. The main arguments involve the cooling speed of white
dwarfs and old neutron stars, the delay of helium ignition in low-mass
red giants, and the helium-burning lifetime of horizontal-branch stars.
The latter two arguments, which are based on observations of globularcluster
stars, are cast into the form of an easy-to-use analytic criterion
that allows for a straightforward application in many different cases.
The cooling speed of nascent neutron stars is discussed in Chapter 11
in the context of supernova neutrinos.
2.1 Stages of Stellar Evolution
2.1.1 The Main Sequence
To identify those observables of stellar structure and evolution that can
be used to constrain or perhaps discover a novel energy-loss mechanism
it is necessary to understand how stars live and die. In Chapter 1 the
basics of the theory of stellar structure have already been discussed.
It is now time to give an overview of the stages of stellar evolution,
and how they manifest themselves in the observable properties of stars.
Because stellar evolution is an old subject, the literature is vast. I
will give reference only to a few recent original papers that I need to
support specific points. Otherwise, detailed quantitative accounts of
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