Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the difference between nuclear and contraction ages   Context:Ages derived from the low mass stars still contracting onto the main
sequence often differ from ages derived from the high mass ones that have
already evolved away from it.
  Aims:We investigate the general claim of disagreement between these two
independent age determinations by presenting UBVRI photometry of the young
galactic open clusters NGC 2232, NGC 2516, NGC 2547 and NGC 4755, spanning the
age range ~10-150 Myr
  Methods: We derive reddenings, distances and nuclear ages by fitting ZAMS and
isochrones to color-magnitudes and color-color diagrams. To derive contraction
ages, we use four different pre-main sequence models, with an empirically
calibrated color-temperature relation to match the Pleiades cluster sequence.
  Results: When using exclusively the V vs. V-I color-magnitude diagram and
empirically calibrated isochrones, there is consistency between nuclear and
contraction ages for the studied clusters. Although the contraction ages seem
systematically underestimated, in none of cases they deviate by more than one
standard deviation from the nuclear ages.

9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th