Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New Insights into the Problem of the Surface Gravity Distribution of
  Cool DA White Dwarfs   We review at length the longstanding problem in the spectroscopic analysis of
cool hydrogen-line (DA) white dwarfs (Teff < 13,000 K) where gravities are
significantly higher than those found in hotter DA stars. The first solution
that has been proposed for this problem is a mild and systematic helium
contamination from convective mixing that would mimic the high gravities. We
constrain this scenario by determining the helium abundances in six cool DA
white dwarfs using high-resolution spectra from the Keck I 10-m telescope. We
obtain no detections, with upper limits as low as He/H = 0.04 in some cases.
This allows us to put this scenario to rest for good. We also extend our model
grid to lower temperatures using improved Stark profiles with non-ideal gas
effects from Tremblay & Bergeron and find that the gravity distribution of cool
objects remains suspiciously high. Finally, we find that photometric masses
are, on average, in agreement with expected values, and that the high-log g
problem is so far unique to the spectroscopic approach.

34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg