Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Infrared Spectroscopy of HR 4796A's Bright Outer Cometary Ring + Tenuous
  Inner Hot Dust Cloud   We have obtained new NASA IRTF SpeX spectra of the HR 4796A debris ring
system. We find a unique red excess flux that extends out to ~9 um in Spitzer
IRS spectra, where thermal emission from cold, ~100K dust from the system's
ring at ~75 AU takes over. Matching imaging ring photometry, we find the excess
consists of NIR reflectance from the ring which is as red as that of old,
processed comet nuclei, plus a tenuous thermal emission component from
close-in, T ~ 850 K circumstellar material evincing an organic plus silicate
emission feature complex at 7 - 13 um. Unusual, emission-like features due to
atomic Si, S, Ca, and Sr were found at 0.96 - 1.07 um, likely sourced by rocky
dust evaporating in the 850 K component. An empirical cometary dust phase
function can reproduce the scattered light excess and 1:5 balance of scattered
vs. thermal energy for the ring with optical depth Tau > 0.10 in an 8 AU wide
belt of 4 AU vertical height and Mdust > 0.1-0.7 M_Mars. Our results are
consistent with HR 4796A consisting of a narrow sheparded ring of devolatilized
cometary material associated with multiple rocky planetesimal subcores, and a
small steady stream of dust inflowing from this belt to a rock sublimation zone
at approximately 1 AU from the primary. These subcores were built from comets
that have been actively emitting large, reddish dust for > 0.4 Myr at 100K, the
temperature at which cometary activity onset is seen in our Solar System.

10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat