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Table 2

Fraction and median isochronal age of Class II, Class III, accreting (CTTS) and non-accreting (WTTS) sources projected onto each of the six subregions of NGC 2264 discussed in Sung et al. (2009).

Class II Class III CTTS WTTS
Tot # % Myr Tot # % Myr Tot # % Myr Tot # % Myr

Spokes 21 10.7 1.71-0.05 15 4.0 4.39-1.08 23 12.3 1.77-0.13 19 4.6 3.31-0.52
Cone (C) 33 16.8 1.91-0.06 37 9.8 4.13-0.49 30 16.0 1.54-0.02 41 10.0 3.77-0.76
Cone (H) 20 10.2 3.96 40 10.6 3.45 23 12.3 4.43 44 10.8 2.86
S Mon 61 31.0 2.65-0.20 111 29.4 3.72+0.03 46 24.6 2.77 121 29.6 3.42
Halo 36 18.3 3.85 120 31.8 4.16 39 20.9 3.90 122 29.8 4.00
Field 26 13.2 6.43 54 14.3 4.60+0.04 26 13.9 6.83 62 15.2 4.60+0.04

Notes. “Tot #” = total number of sources in the corresponding category (Class II, Class III, CTTS, or WTTS) that are comprised within the corresponding NGC 2264 subregion. “%” = percentage of sources in the corresponding category, with respect to the total number of NGC 2264 sources falling into that category, located onto the corresponding NGC 2264 subregion. “Myr” = median isochronal age associated with sources in the corresponding category in the corresponding NGC 2264 subregion. Age estimates from our analysis are available only for sources that populate the area of the HR diagram delimited on the right by the 0.5 Myr isochrone, on the left by the 1 Gyr isochrone, and on the top by the 1.4 M mass track (see Sect. 4.2). To take the first and second limit into account in our median ages, these are reported as (where applicable): m is the median value of the measured isochronal ages in each subgroup; mdm1 is the computed median if we include objects that would appear younger than 0.5 Myr on the HR diagram; m + dm2 is the computed median if we include objects that would appear older than the others on the HR diagram.

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