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Table 3.
Astrometric, kinematic, and physical parameters of NGC 6618.
| Equatorial | ||
|---|---|---|
| Right ascension | α | 275.123 ± 0.001 deg |
| Declination | δ | –16.177 ± 0.001 deg |
| Proper motion (a) | μα* | 0.218 mas yr−1 |
| Proper motion (a) | μδ | –1.623 mas yr−1 |
| μα* dispersion | σα | 3.4 km s−1 |
| μδ dispersion | σδ | 2.2 km s−1 |
| Galactic | ||
| Galactic longitude | l | 15.058 ± 0.001 deg |
| Galactic latitude | b | –0.686 ± 0.001 deg |
| Proper motion (a) | μl* | –1.329 mas yr−1 |
| Proper motion (a) | μb | –0.957 mas yr−1 |
| μl* dispersion | σl | 2.1 km s−1 |
| μb dispersion | σb | 3.5 km s−1 |
| Radial | ||
| Parallax | ϖ | 0.5974 ± 0.0065 mas |
| Distance | d | 1674 pc |
| Radial velocity (b) | vR | 6.4 km s−1 |
| vR dispersion (1) | σR | 5.5 ± 0.5 km s−1 |
| Physical properties | ||
| Mass | Mcl | ∼5.1 × 103 M⊙ |
| Radius | rcl | 0.2–1.0 pc |
| Age (runaways) | – | 0.65 ± 0.25 Myr |
| Age (literature) | – | ≲1 Myr |
| Visual extinction | AV | > 2.0 mag |
| Number of O stars | – | ∼21 |
Notes.
(b)
Mean of radial velocities in Ramírez-Tannus et al. (2017).
Reference. (1)Ramírez-Tannus et al. (2021).
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