Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Distributions of Short-Lived Radioactive Nuclei Produced by Young
  Embedded Stellar Clusters   Most star formation in the Galaxy takes place in clusters, where the most
massive members can affect the properties of other constituent solar systems.
This paper considers how clusters influence star formation and forming
planetary systems through nuclear enrichment from supernova explosions, where
massive stars deliver short-lived radioactive nuclei (SLRs) to their local
environment. The decay of these nuclei leads to both heating and ionization,
and thereby affects disk evolution, disk chemistry, and the accompanying
process of planet formation. Nuclear enrichment can take place on two spatial
scales: [1] Within the cluster itself ($\ell\sim1$pc), the SLRs are delivered
to the circumstellar disks associated with other cluster members. [2] On the
next larger scale ($\ell\sim2-10$pc), SLRs are injected into the background
molecular cloud; these nuclei provide heating and ionization to nearby
star-forming regions, and to the next generation of disks. For the first
scenario, we construct the expected distributions of radioactive enrichment
levels provided by embedded clusters. Clusters can account for the SLR mass
fractions inferred for the early Solar Nebula, but typical SLR abundances are
lower by a factor of $\sim10$. For the second scenario, we find that
distributed enrichment of SLRs in molecular clouds leads to comparable
abundances. For both the direct and distributed enrichment processes, the
masses of $^{26}$Al and $^{60}$Fe delivered to individual circumstellar disks
typically fall in the range $10-100pM_\odot$ (where
$1pM_\odot=10^{-12}M_\odot$). The corresponding ionization rate due to SLRs
typically falls in the range $\zeta_{SLR}\sim1-5\times10^{-19}$ sec$^{-1}$.
This ionization rate is smaller than that due to cosmic rays,
$\zeta_{CR}\sim10^{-17}$ sec$^{-1}$, but will be important in regions where
cosmic rays are attenuated (e.g., disk mid-planes).

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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: nlin
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: stat
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The categories of this paper are: hep-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int