Globular Star Cluster Messier 5 in Serpens Caput: Surprising 'Vitality' | Hubble

Globular Star Cluster Messier 5 in Serpens Caput: Surprising 'Vitality' | Hubble

The globular cluster Messier 5, shown here in this NASA/European Space Agency Hubble Space Telescope image, is one of the oldest belonging to the Milky Way galaxy. The majority of its stars formed more than 12 billion years ago, but there are unexpected newcomers on the scene, adding vitality to this aging population.

Stars in globular clusters form in the same stellar nursery and grow old together. The most massive stars age quickly, exhausting their fuel supply in less than a million years, and end their lives in spectacular supernovae explosions. This process should have left the ancient cluster Messier 5 with only old, low-mass stars. These stars have aged and cooled and have become red giants, while the oldest stars have evolved even further into blue horizontal branch stars.

Yet astronomers have spotted many young, blue stars in this cluster, hiding amongst the much more luminous ancient ones. Astronomers think that these laggard youngsters, called blue stragglers, were created either by stellar collisions or by the transfer of mass between binary stars. Such events are easy to imagine in densely populated globular clusters where a few million stars are tightly packed together.

Messier 5 lies at a distance of about 25,000 light-years in the constellation of Serpens (The Snake). This image was taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys. The picture was created from images taken through a blue filter (F435W, colored blue), a red filter (F625W, colored green) and a near-infrared filter (F814W, colored red). The total exposure times per filter were 750 s, 400 s and 567 s, respectively. The field of view is about 2.6 arcminutes across.

Credit: ESA/Hubble & NASA 

Release Date: May 2, 2011

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