Terzan 7
| Terzan 7 | |
|---|---|
Terzan7 by Hubble Space Telescope; 3.5′ view | |
| Observation data (J2000 epoch) | |
| Constellation | Sagittarius |
| Right ascension | 19h 17m 43.92s |
| Declination | −34° 39′ 27.8″ |
| Distance | 75.7 kly (23.2 kpc) |
| Apparent magnitude (V) | 12.0 |
| Apparent dimensions (V) | 7.3′ |
| Physical characteristics | |
| Radius | 160 ly[a] |
| VHB | 17.76 |
| Estimated age | 7.5 Gyr |
| Notable features | young extragalactic globular |
| Other designations | Ter 7, GCl 109.1 |
Terzan 7 is a sparse and young globular cluster that is believed to have originated in the Sagittarius Dwarf Spheroidal Galaxy (Sag DEG) and is physically associated with it. It is relatively metal rich with [Fe/H] = -0.6 and an estimated age of 7.5 Gyr. Terzan 7 has low levels of nickel ([Ni/Fe] = -0.2) which supports its membership in the Sag DEG system since it has a similar chemical signature. It has a rich population of blue stragglers that are strongly concentrated toward the center of Terzan 7. It has an average luminosity distribution of Mv = -5.05. It has a half-light radius (Rh) of 6.5pc.