Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High spatial resolution mid-infrared observations of the low-mass young
  star TW Hya   We want to improve knowledge of the structure of the inner few AU of the
circumstellar disk around the nearby T Tauri star TW Hya. Earlier studies have
suggested the existence of a large inner hole, possibly caused by interactions
with a growing protoplanet. We used interferometric observations in the N-band
obtained with the MIDI instrument on the Very Large Telescope Interferometer,
together with 10 micron spectra recorded by the infrared satellite Spitzer. The
fact that we were able to determine N-band correlated fluxes and visibilities
for this comparatively faint source shows that MIR interferometry can be
applied to a large number of low-mass young stellar objects.
  The MIR spectra obtained with Spitzer reveal emission lines from HI (6-5), HI
(7-6), and [Ne II] and show that over 90% of the dust we see in this wavelength
regime is amorphous. According to the correlated flux measured with MIDI, most
of the crystalline material is in the inner, unresolved part of the disk, about
1 AU in radius. The visibilities exclude the existence of a very large (3-4 AU
radius) inner hole in the circumstellar disk of TW Hya, which was required in
earlier models. We propose instead a geometry of the inner disk where an inner
hole still exists, but at a much reduced radius, with the transition from zero
to full disk height between 0.5 and 0.8 AU, and with an optically thin
distribution of dust inside. Such a model can comply with SED and MIR
visibilities, as well as with visibility and extended emission observed in the
NIR at 2 micron. If a massive planet was the reason for this inner hole, as has
been speculated, its orbit would have to be closer to the star than 0.3 AU.
Alternatively, we may be witnessing the end of the accretion phase and an early
phase of an inward-out dispersal of the circumstellar disk.

14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin