Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantitative estimates of the surface habitability of Kepler-452b   Kepler-452b is currently the best example of an Earth-size planet in the
habitable zone of a sun-like star, a type of planet whose number of detections
is expected to increase in the future. Searching for biosignatures in the
supposedly thin atmospheres of these planets is a challenging goal that
requires a careful selection of the targets. Under the assumption of a
rocky-dominated nature for Kepler-452b, we considered it as a test case to
calculate a temperature-dependent habitability index, $h_{050}$, designed to
maximize the potential presence of biosignature-producing activity (Silva et
al.\ 2016). The surface temperature has been computed for a broad range of
climate factors using a climate model designed for terrestrial-type exoplanets
(Vladilo et al.\ 2015). After fixing the planetary data according to the
experimental results (Jenkins et al.\ 2015), we changed the surface gravity,
CO$_2$ abundance, surface pressure, orbital eccentricity, rotation period, axis
obliquity and ocean fraction within the range of validity of our model. For
most choices of parameters we find habitable solutions with $h_{050}>0.2$ only
for CO$_2$ partial pressure $p_\mathrm{CO_2} \lesssim 0.04$\,bar. At this
limiting value of CO$_2$ abundance the planet is still habitable if the total
pressure is $p \lesssim 2$\,bar. In all cases the habitability drops for
eccentricity $e \gtrsim 0.3$. Changes of rotation period and obliquity affect
the habitability through their impact on the equator-pole temperature
difference rather than on the mean global temperature. We calculated the
variation of $h_{050}$ resulting from the luminosity evolution of the host star
for a wide range of input parameters. Only a small combination of parameters
yield habitability-weighted lifetimes $\gtrsim 2$\,Gyr, sufficiently long to
develop atmospheric biosignatures still detectable at the present time.

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The categories of this paper are: q-bio
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th