Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: IRAS 05436-0007 and the Emergence of McNeil's Nebula   We present a study of McNeil's Nebula, a newly appeared reflection nebula in
the L1630 cloud, together with photometry and spectroscopy of its source. New
IR photometry compared to earlier 2MASS data shows that the star has brightened
by about 3 magnitudes in the near-infrared, changing its location in a J-H/H-K
diagram precisely along a reddening vector. A Gemini NIRI K-band spectrum shows
strong CO-bandhead emission and Br-gamma is in emission, indicative of strong
accretion. A Gemini GMOS optical spectrum shows only a red, heavily veiled
continuum, with H-alpha strongly in emission and displaying a pronounced P
Cygni profile, with an absorption trough reaching velocities up to 600 km s-1.
This implies significant mass loss in a powerful wind. However, no evidence is
found for any shocks, as commonly seen in collimated outflows from young stars.
Apparently the eruption has dispersed a layer of extinction and this, together
with the intrinsic brightening of the IRAS source, has allowed an earlier
outflow cavity to be flooded with light, thus creating McNeil's Nebula.

31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga