Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The influence of radiative core growth on coronal X-ray emission from
  pre-main sequence stars   Pre-main sequence (PMS) stars of mass $\gtrsim0.35\,{\rm M}_\odot$ transition
from hosting fully convective interiors to configurations with a radiative core
and outer convective envelope during their gravitational contraction. This
stellar structure change influences the external magnetic field topology and,
as we demonstrate herein, affects the coronal X-ray emission as a stellar
analog of the solar tachocline develops. We have combined archival X-ray,
spectroscopic, and photometric data for $\sim$1000 PMS stars from five of the
best studied star forming regions; the ONC, NGC 2264, IC 348, NGC 2362, and NGC
6530. Using a modern, PMS calibrated, spectral type-to-effective temperature
and intrinsic colour scale, we deredden the photometry using colours
appropriate for each spectral type, and determine the stellar mass, age, and
internal structure consistently for the entire sample. We find that PMS stars
on Henyey tracks have, on average, lower fractional X-ray luminosities ($L_{\rm
X}/L_\ast$) than those on Hayashi tracks, where this effect is driven by
changes in $L_{\rm X}$. X-ray emission decays faster with age for higher mass
PMS stars. There is a strong correlation between $L_\ast$ and $L_{\rm X}$ for
Hayashi track stars but no correlation for Henyey track stars. There is no
correlation between $L_{\rm X}$ and radiative core mass or radius. However, the
longer stars have spent with radiative cores, the less X-ray luminous they
become. The decay of coronal X-ray emission from young early K to late G-type
PMS stars, the progenitors of main sequence A-type stars, is consistent with
the dearth of X-ray detections of the latter.

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The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys