Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A cosmic abundance standard: chemical homogeneity of the solar
  neighbourhood and the ISM dust-phase composition   A representative sample of unevolved early B-type stars in nearby OB
associations and the field is analysed to unprecedented precision using NLTE
techniques. The resulting chemical composition is found to be more metal-rich
and much more homogeneous than indicated by previous work. A rms scatter of
~10% in abundances is found for the six stars (and confirmed by six evolved
stars), the same as reported for ISM gas-phase abundances. A cosmic abundance
standard for the present-day solar neighbourhood is proposed, implying mass
fractions for hydrogen, helium and metals of X=0.715, Y=0.271 and Z=0.014. Good
agreement with solar photospheric abundances as reported from recent 3D
radiative-hydrodynamical simulations of the solar atmosphere is obtained. As a
first application we use the cosmic abundance standard as a proxy for the
determination of the local ISM dust-phase composition, putting tight
observational constraints on dust models.

36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex