By placing the stars in a globular cluster on a Hertzprung-Russell diagram, ... The globular cluster NGC 6397 is 7,800 light-years away. If the light we observe is 7,800 years old, ...

Cluster Gaia DR3 CMD (B versus B-R) diagram fitted with a Padova theoretical isochrone (Bressan et al. (2012), Marigo et al. (2013) for adopted cluster parameters ...

Hubble Space Telescope observations of the stellar cluster NGC 1651, which is approximately two billion years old, show that the colour–brightness distribution of stars old enough to have left ...