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Table 2.

Binary statistics and fractions for the spectroscopic systems containing at least one O-type star present in the census.

Group Single Binary O stars Fraction
O-stars O-systems in binaries
O-002 (Trumpler 14) 10 3 5 0.33
O-003 (Trumpler 16 W) 2 2 3 0.60
O-025 (Trumpler 16 E) 8 6 10 0.55
O-027 (Trumpler 15) 3 0
O-028 (Collinder 228) 16 3 4 0.15
O-029 (Collinder 232) 2 0
O-030 (Bochum 11) 4 1 2 0.33
Car OB1 10 4 6 0.37

Whole sample 55 19 30 0.35

Notes. Background and foreground members are excluded from the statistics. We separate numbers considering the different Villafranca groups of Carina. Car OB1 group refers to the stars just falling in the gaps between defined Villafranca groups (see Appendix A for further details).

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