Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ambipolar-Diffusion Timescale, Star-Formation Timescale, and the Ages of
  Molecular Clouds: Is There a Discrepancy?   We re-examine critically the estimates of the duration of different phases of
star formation and the lifetimes of molecular clouds, based on the ages of
T-Tauri stars, age spreads of stars in clusters, and statistics of pre-stellar
cores. We show that all available observational data are consistent with
lifetimes of molecular clouds comparable to 10 Myr, as well as with the
predictions of the theory of self-initiated, ambipolar-diffusion--controlled
star formation. We conclude that there exists no observational support for
either "young" molecular clouds or "rapid" star formation.

23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc