Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Solution to the debris disc mass problem: planetesimals are born small?   Debris belts on the periphery of planetary systems, encompassing the region
occupied by planetary orbits, are massive analogues of the Solar system's
Kuiper belt. They are detected by thermal emission of dust released in
collisions amongst directly unobservable larger bodies that carry most of the
debris disc mass. We estimate the total mass of the discs by extrapolating up
the mass of emitting dust with the help of collisional cascade models. The
resulting mass of bright debris discs appears to be unrealistically large,
exceeding the mass of solids available in the systems at the preceding
protoplanetary stage. We discuss this "mass problem" in detail and investigate
possible solutions to it. These include uncertainties in the dust opacity and
planetesimal strength, variation of the bulk density with size, steepening of
the size distribution by damping processes, the role of the unknown
"collisional age" of the discs, and dust production in recent giant impacts.
While we cannot rule out the possibility that a combination of these might
help, we argue that the easiest solution would be to assume that planetesimals
in systems with bright debris discs were "born small", with sizes in the
kilometre range, especially at large distances from the stars. This conclusion
would necessitate revisions to the existing planetesimal formation models, and
may have a range of implications for planet formation. We also discuss
potential tests to constrain the largest planetesimal sizes and debris disc
masses.

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The categories of this paper are: math
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The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
16
The categories of this paper are: stat
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The categories of this paper are: eess
24
The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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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: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: cs
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The categories of this paper are: hep-lat