| NGC 7209 | |
|---|---|
 | |
| Observation data (J2000epoch) | |
| Right ascension | 22h 05m 07s[1] |
| Declination | +46° 29′ 00″[1] |
| Distance | 3,810ly (1,168pc[2]) |
| Apparent magnitude (V) | 7.7[1] |
| Apparent dimensions (V) | 25' |
| Physical characteristics | |
| Mass | 278[3] M☉ |
| Estimated age | 420 million years[2] |
| Other designations | Cr 444 |
| Associations | |
| Constellation | Lacerta |
| See also:Open cluster,List of open clusters | |
NGC 7209 is anopen cluster in the constellationLacerta. It was discovered byWilliam Herschel on 19 October 1787. The cluster lies 3,810 light years away from Earth. It has been suggested that there is another cluster at a distance of 2,100 light years projected in front of a cluster lying at 3,800 light years away, based on thereddening of the cluster,[4] however, further photometric studies of the cluster did not support that claim.[5]
The cluster is made up out of 150 stars with magnitude from 9 to 15[6] within a tidal radius of 9 parsec (30 light years).[3] From its members, 3 are probablydelta Scuti variables.[7] One other member of the cluster is thevariable SS Lancertae, abinary star with 14.4 day period whose magnitude stopped varying in the middle of the 20th century. This has been attributed to the presence of a third star with period 679 days, whose perturbations change the line of sight. The nodal cycle is found to be about 600 years, within which occur two ecliptic phases, each lasting about 100 yr.[8]
Media related toNGC 7209 at Wikimedia Commons