47 Tucanae core

The core of the globular cluster 47 Tucanae, as imaged by the European Space Agency's Faint Object Camera (FOC) onboard NASA/ESA Hubble Space Telescope. Space Telescope's high spatial resolution and ultraviolet sensitivity make it a powerful tool for probing the centers of globular clusters. The FOC resolves several hundred stars where ground-based images only yield a few dozen stars. At least 21 of these stars are exceptionally bright in ultraviolet light. HST's UV sensitivity and high resolution allow it to easily separate these so-called blue stragglers stars from the red giant stars which dominate the cluster.

Blue stragglers may evolve from "old age" back to a hotter and brighter youth through stellar collisions and mergers. This high concentration of blue stragglers towards the core of 47 Tucanae suggests they are significantly more massive than most of the cluster's stars. Some of blue stragglers could be massive because they are really double star systems. Such binary systems may influence the motions of thousands of other stars within the cluster.


Francesco Paresce (ESA/STScI). Michael Shara (STScI), Georges Meylan (ESA/STScI)

About the Image

NASA press release
NASA caption
Release date:24 July 1991, 06:00
Size:3289 x 2305 px

About the Object

Name:47 Tucanae, NGC 104
Type:Milky Way : Star : Grouping : Cluster : Globular
Distance:15000 light years
Category:Star Clusters

Image Formats

Large JPEG
2.4 MB
Screensize JPEG
194.0 KB

Colours & filters

220 nm Hubble Space Telescope

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