Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anomalous CO2 Ice Toward HOPS-68: A Tracer of Protostellar Feedback   We report the detection of a unique CO2 ice band toward the deeply embedded,
low-mass protostar HOPS-68. Our spectrum, obtained with the Infrared
Spectrograph onboard the Spitzer Space Telescope, reveals a 15.2 micron CO2 ice
bending mode profile that cannot modeled with the same ice structure typically
found toward other protostars. We develop a modified CO2 ice profile
decomposition, including the addition of new high-quality laboratory spectra of
pure, crystalline CO2 ice. Using this model, we find that 87-92% of the CO2 is
sequestered as spherical, CO2-rich mantles, while typical interstellar ices
show evidence of irregularly-shaped, hydrogen-rich mantles. We propose that (1)
the nearly complete absence of unprocessed ices along the line-of-sight is due
to the flattened envelope structure of HOPS-68, which lacks cold absorbing
material in its outer envelope, and possesses an extreme concentration of
material within its inner (10 AU) envelope region and (2) an energetic event
led to the evaporation of inner envelope ices, followed by cooling and
re-condensation, explaining the sequestration of spherical, CO2 ice mantles in
a hydrogen-poor mixture. The mechanism responsible for the sublimation could be
either a transient accretion event or shocks in the interaction region between
the protostellar outflow and envelope. The proposed scenario is consistent with
the rarity of the observed CO2 ice profile, the formation of nearly pure CO2
ice, and the production of spherical ice mantles. HOPS-68 may therefore provide
a unique window into the protostellar feedback process, as outflows and heating
shape the physical and chemical structure of protostellar envelopes and
molecular clouds.

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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-th
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th