Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Mexican Million Models Database: a virtual observatory for gaseous
  nebulae   The 3MdB (Mexican Million Models database) is a large database of
photoionization models for H II regions. The number of free parameters for the
models is close to 15, including the description of the ionizing Spectral
Energy Distribution (effective temperature, luminosity, surface gravity, for
different type of stellar atmosphere models) and the description of the ionized
gas (distance to the ionizing source, density, abundances of the most common
elements, dust). The outputs of the models are more than 70 emission line
intensities, the ionic fractions and temperatures. All the parameters and
outputs are included in the MySQL database, giving the possibility to the user
to search into the database for example for all the models that reproduce a
given set of observations.

19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom