Table 1.
Fundamental physical parameters describing the Cygnus OB2 association.
| Ref. | ||
|---|---|---|
| RA (J2000) | 20h33m12s | 1 |
| Dec (J2000) | +41° 19′00″ | 1 |
| Stellar mass |
 M⊙ |
2 |
| Virial mass | (9.3 ± 0.8)×105 M⊙ | 3 |
| Volume density | ∼100 stars pc−3 | 4 |
| Age | 1–7 Myr (Peak 4–5 Myr) | 2 |
| Distance | 1.4 ± 0.08 kpc | 5 |
| Visual extinction, AV | 4m − 7m (IQR⋆) | 2 |
| OB members | 2600 ± 400 | 6 |
| Binary fraction | 55% | 7 |
| 3D velocity dispersion | 17.8 ± 0.6 km s−1 | 3 |
| Half-light radius | 10.1 ± 0.9′(4.1 pc) | 3 |
| Observational diameter | ∼2° (∼49 pc) | 6 |
Notes. The RA and Dec describe the centre of the association as chosen by numerous authors based on the position of the main concentration of OB stars. ( ⋆ )Interquartile range (IQR).
References. (1) Wright et al. (2014a), (2) Wright et al. (2015), (3) Wright et al. (2016), (4) Wright et al. (2014b), (5) Rygl et al. (2012), (6) Knödlseder (2000), (7) Kobulnicky et al. (2014).
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