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> White dwarves stars in globular cluster NGC 6397

White dwarves stars in globular cluster NGC 6397

author: Nasa/Esa/Novapix

reference: a-agb63-97004

Image Size 300 DPI: 15 * 11 cm

This image shows young and old white dwarf stars " the burned-out relics of normal stars " in the ancient globular star cluster NGC 6397. The image, taken by Hubble's Advanced Camera for Surveys, reveals young white dwarfs less than 800 million years old and older white dwarfs between 1.4 and 3.5 billion years old. The photo shows 12 of the 84 white dwarfs in the Hubble study. The blue squares pinpoint the young white dwarfs; the red circles outline the older white dwarfs. The Hubble researchers distinguished the younger from the older white dwarfs based on their color and brightness. The younger white dwarfs are hotter and therefore bluer and brighter than the older ones. The astronomers were surprised to find young white dwarfs far away from the cluster's core. They had assumed that the youngsters would reside at the center and migrate over time to the cluster's outskirts. The astronomers proposed that the cluster stars that burn out as white dwarfs are given a boost that propels them to the edge of the cluster. The Hubble images were taken in March and April 2005.

Keywords for this photo:

ARA - ASTRONOMY - GLOBULAR CLUSTER - HST - HUBBLE SPACE TELESCOPE - NGC 6397 - SOUTHERN HEMISPHERE - STAR - STAR CLUSTER - WHITE DWARF -