M19
NGC 6273
Dati oggetto
- Designazione catalogo
- M19
- Tipo
- GlobularCluster
- Costellazione
- Ophiuchus
- Magnitudine
- 6.8
- Ascensione retta
- 17h 02m 37.7s
- Declinazione
- -26° 16' 04.6"
- Distanza
- 28,700 anni luce
- Dimensione angolare
- 13.5
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Su M19
Descrizione
M19 is one of the most oblate (flattened) globular clusters known, located about 28,700 light-years from Earth in Ophiuchus. It lies very close to the galactic center — only about 6,500 light-years from it — and the Milky Way's tidal forces are likely responsible for its elongated shape. The cluster contains several hundred thousand stars.
Consigli per l'osservazione
Located about 8 degrees due east of Antares. Appears as a small, oval fuzzy patch in binoculars. A 4-inch telescope shows a bright, slightly elongated glow. Resolving stars requires 8 inches or more. Look carefully for the elongated shape — M19 is visibly non-circular even in moderate apertures. Best observed from June through August.
Storia
Discovered by Charles Messier on June 5, 1764. He described it as a 'nebula without stars.' William Herschel resolved it into stars and noted its elliptical shape. Modern studies confirm it is one of the most flattened globular clusters in the Milky Way.
Curiosità
M19's oblateness (ellipticity of about 0.3) is remarkable among globular clusters, which are typically quite round. Its proximity to the galactic center subjects it to intense tidal forces that distort its shape. The cluster is heavily reddened by interstellar dust, losing about 1.5 magnitudes of brightness.
Foto della comunità (1)
Credit: Doug Williams, REU Program / NOIRLAB / NSF / AURA. License: CC BY-SA 4.0. (Wikimedia Commons)
Skybred Feb 28, 2026