| NGC 6649 | |
|---|---|
 NGC 6649 byPanSTARRS | |
| Observation data (J2000epoch) | |
| Right ascension | 18h 33m 26s[1] |
| Declination | −10° 23′ 56″[1] |
| Distance | 4,470ly[2] (1,370pc[2]) |
| Apparent magnitude (V) | 8.9[1] |
| Apparent dimensions (V) | 5.0' |
| Physical characteristics | |
| Estimated age | 60 million years[3] |
| Other designations | Collinder 384 |
| Associations | |
| Constellation | Scutum |
| See also:Open cluster,List of open clusters | |
NGC 6649 is anopen cluster in the constellationScutum. It was discovered byWilliam Herschel on 10 July, 1787. The cluster is about 40–60 million years old and it is located 4,500 light years away.Cepheid variable V367 Scuti is a member of the cluster.[4][5]
NGC 6649 is a rich cluster with more than a thousand members with apparent magnitude over 20 extending at a radial distance of about 21 arcminutes, with the core of the cluster having a radius of 2.4 arcminutes, which corresponds to 1.4 parsecs at the distance of the cluster. The tidal radius of the cluster is estimated to be35.85±6.64 arcminutes, which corresponds to about 21 parsecs at the distance of the cluster, indicating a cluster with a dense core and an extended halo. Two smaller clusters have been detected in the vicinity of the cluster, forming a triple system.[3]
Theturnoff point of NGC 6649 is estimated to be at 4.8M☉, which corresponds to aspectral type of B5.[6] A total of 59 stars are estimated to be of spectral type B, indicating an original star mass of about 2,600M☉.[6] Twored supergiants are also members of the cluster based on the reddening, along with a Cepheid variable, V367 Scuti.[6] Seven members of the cluster are found to beBe stars,[7] and the cluster hosts twoblue straggler star candidates.[6] Themetallicity of the cluster is estimated to be [Fe/H] = +0.02 ± 0.07, slightly below the expected value based on the mean galactic gradient.[6]
