Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Imaging and Spatially Resolved Spectroscopy of AFGL 2688 in the Thermal
  Infrared Region   We present ground-based high-resolution (~0".3) imaging of AFGL 2688 at L'
(3.8 um) and M'(4.7um). A wealth of structure in the central region is revealed
due to less extinction in the thermal infrared. A clear border in the southern
lobe at L' corresponds to the edge of the heavily obscured region in visible,
indicating there is a dense material surrounding the central region. The images
also show a narrow dark lane oriented to 140 deg east of north with the normal
at 50 deg. The normal position angle is inconsistent with the optical polar
axis (PA = 15 deg), but is aligned to the high-velocity CO components found in
the radio wavelength observations. The central star remains invisible at L' and
M'. Several clumpy regions in the north lobe dominate in L' and M' luminosity.
In particular a pointlike source (peak A) at 0".5 northeast of the center of
the nebula exhibits the highest surface brightness with a very red spectral
energy distribution (SED). Based on the almost identical SED as adjacent
regions, we suggest that the pointlike source is not self-luminous, as was
proposed, but is a dense dusty blob reflecting thermal emission from the
central star.
  We also present spatially resolved slit spectroscopy of the bright dusty
blobs. An emission feature at 3.4 um as well as at 3.3 um is detected
everywhere within our field of view. There is no spatial variation in the
infrared emission feature (IEF) throughout the observed area (0".2-1".5, or
240-1800 AU from the central source). The constant flux ratio of the emission
feature relative to the continuum is consistent with the view that the blobs
are mostly reflecting the light from the central star in the 3 um region.

35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math