Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cold CO gas in the envelopes of FU Orionis-type young eruptive stars   FUors are young stellar objects experiencing large optical outbursts due to
highly enhanced accretion from the circumstellar disk onto the star. FUors are
often surrounded by massive envelopes, which play a significant role in the
outburst mechanism. Conversely, the subsequent eruptions might gradually clear
up the obscuring envelope material and drive the protostar on its way to become
a disk-only T Tauri star. Here we present an APEX $^{12}$CO and $^{13}$CO
survey of eight southern and equatorial FUors. We measure the mass of the
gaseous material surrounding our targets. We locate the source of the CO
emission and derive physical parameters for the envelopes and outflows, where
detected. Our results support the evolutionary scenario where FUors represent a
transition phase from envelope-surrounded protostars to classical T Tauri
stars.

4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph