Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring the Expansion and Age of the Nova Shell IPHASXJ210204.7+471015   The parallax expansion and kinematics of a nova shell can be used to assess
its age and distance, and to investigate the interaction of the ejecta with the
circumstellar medium. These are key to understand the expansion and dispersal
of the nova ejecta in the Galaxy. Multi-epoch images and high-dispersion
spectroscopic observations of the recently discovered classical nova shell
IPHASXJ210204.7+471015 around a nova-like system have been used to derive a
present day expansion rate of 0.100 arcsec/yr and an expansion velocity of 285
km/s. These data are combined to obtain a distance of 600 pc to the nova. The
secular expansion of the nova shell place the event sometime between 1850 and
1890, yet it seems to have been missed at that time. Despite its young age,
130-170 yrs, we found indications that the ejecta has already experienced a
noticeable deceleration, indicating the interaction of this young nova shell
with the surrounding medium.

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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: nlin
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci