NGC 6624
Globular cluster NGC 6624 |
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The globular cluster NGC 6624, imaged by the Hubble Space Telescope | |
AladinLite | |
Constellation | Sagittarius |
Position equinox : J2000.0 , epoch : J2000.0 |
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Right ascension | 18 h 23 m 40.6 s |
declination | -30 ° 21 ′ 41 ″ |
Appearance | |
Concentration class | VI |
Brightness (visual) | 7.6 likes |
Angular expansion | 8.8 ' |
Color excess E (BV) (redness) |
0.28 |
Physical data | |
Radial velocity | +53.9 ± 0.6 km / s km / s |
distance | 25.8 ly |
Absolute brightness | −7.5 M mag |
Core radius | 0.06 ' |
Tidal radius | 20.55 ' |
Concentration lg (r t / r c ) | 2.5 |
Metallicity [Fe / H] | −0.44 |
history | |
discovery | William Herschel |
Discovery date | June 24, 1784 |
Catalog names | |
NGC 6624 • C 1820-303 • GCl 93 • ESO 457-SC011 • GC 4404 • H I 50, h 3742 |
NGC 6624 is a globular cluster discovered on June 24, 1784 by the German-British astronomer Wilhelm Herschel , which is located in the constellation Sagittarius . The globular cluster has an apparent magnitude of 7.6 mag.
Six pulsars are known in NGC 6624 . PSR J1823-3021A was the first to be detected in the globular cluster in 1994. With the help of the American Fermi Gamma-ray Space Telescope , a team led by Damien Parent was able to detect gamma radiation from this remnant of the star in 2011. The object is thus the first known gamma pulsar in a globular cluster and also holds a new distance record for gamma pulsars. The researchers determined an upper limit of 25 million years for the age of the neutron star. The pulsar is not only the youngest millisecond pulsar to be discovered, but also has the strongest magnetic field of all known objects of this class.
In NGC 6624 there are also PSR B1820-30A, PSR B1820-30B and PSR B1820-30C as well as the X-ray burster Sagittarius X-4 (X 1820-30), a low - mass X - ray binary star with an orbital period of only 11.5 minutes .
Web links
- Page on NGC 6624 in the Galactic Globular Clusters Database
- Time-Resolved Ultraviolet Observations of the Globular Cluster X-Ray Source in NGC 6624: The Shortest Known Period Binary System