Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ISO SWS/LWS observations of SN 1987A   We report on observations of SN 1987A with ISO SWS/LWS made 9 - 11 years
after the explosion. No emission from the supernova was seen. In particular,
the upper limits on the fluxes of [Fe I] 24.05 microns and [Fe II] 25.99
microns on day 3999 are roughly 1.1 Jy and 1.4 Jy, respectively. Assuming a
homogeneous distribution of Ti-44 inside 2000 km/s, we have made theoretical
models to estimate the mass of ejected Ti-44. Assessing various uncertainties
of the model, we obtain an upper limit of 1.5\EE{-4} solar masses. The
implications of this are discussed.
  The LWS data display continuum emission as well as nebular lines of [O I], [C
II] and [O III] from neighboring photoexcited regions in the LMC. The [O III]
lines indicate an electron density of 120 +/- 75 cm^{-3}, and the continuum can
be explained by dust with a temperature of roughly 37 K. A second dust
component with approximately 10 K may also be present.

22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat