Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurements of Physical Parameters of White Dwarfs: A Test of the
  Mass-Radius Relation   We present a detailed spectroscopic and photometric analysis of 219 DA and DB
white dwarfs for which trigonometric parallax measurements are available. Our
aim is to compare the physical parameters derived from the spectroscopic and
photometric techniques, and then to test the theoretical mass-radius relation
for white dwarfs using these results. The agreement between spectroscopic and
photometric parameters is found to be excellent, especially for effective
temperatures, showing that our model atmospheres and fitting procedures provide
an accurate, internally consistent analysis. Values of surface gravity and
solid angle, obtained respectively from spectroscopy and photometry, are
combined with parallax measurements in various ways to study the validity of
the mass-radius relation from an empirical point of view. After a thorough
examination of our results, we find that 73% and 92% of the white dwarfs are
consistent within 1 and 2$\sigma$ confidence levels, respectively, with the
predictions of the mass-radius relation, thus providing strong support to the
theory of stellar degeneracy. Our analysis also allows us to identify 15 stars
that are better interpreted in terms of unresolved double degenerate binaries.
Atmospheric parameters for both components in these binary systems are obtained
using a novel approach. We further identify a few white dwarfs that are
possibly composed of an iron core rather than a carbon/oxygen core, since they
are consistent with Fe-core evolutionary models.

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The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
3
The categories of this paper are: physics