Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling the solar twin 18 Sco   Solar twins are objects of great interest in that they allow us to understand
better how stellar evolution and structure are affected by variations of the
stellar mass, age and chemical composition in the vicinity of the commonly
accepted solar values. We aim to use the existing spectrophotometric,
interferometric and asteroseismic data for the solar twin 18 Sco to constrain
stellar evolution models. 18 Sco is the brightest solar twin and is a good
benchmark for the study of solar twins. The goal is to obtain realistic
estimates of its physical characteristics (mass, age, initial chemical
composition, mixing-length parameter) and realistic associated uncertainties
using stellar models. We set up a Bayesian model that relates the statistical
properties of the data to the probability density of the stellar parameters.
Special care is given to the modelling of the likelihood for the seismic data,
using Gaussian mixture models. The probability densities of the stellar
parameters are approximated numerically using an adaptive MCMC algorithm. From
these approximate distributions we proceeded to a statistical analysis. We also
performed the same exercise using local optimisation. The precision on the mass
is approximately 6%. The precision reached on X0 and Z0 and the mixing-length
parameter are respectively 6%, 9%, and 35%. The posterior density for the age
is bimodal, with modes at 4.67 Gyr and 6.95 Gyr, the first one being slightly
more likely. We show that this bimodality is directly related to the structure
of the seismic data. When asteroseismic data or interferometric data are
excluded, we find significant losses of precision for the mass and the initial
hydrogen-mass fraction. Our final estimates of the uncertainties from the
Bayesian analysis are significantly larger than values inferred from local
optimization.

18
The categories of this paper are: econ
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph