Globular clusters 47
Tucanae are huge spherical cloud of old stars held together by gravity. They
are turning around the cores of galaxies, and satellites orbiting Earth. These
groups of stars contain very little gas and dust - it is believed that most of
the cluster has been driven by winds and explosions of stars it contains, or
has been torn by the interstellar gas has been interacting with the cluster.
Any remaining material coalesced into stars billions of years ago.
47 Tucanae, also known
as NGC 104, is a huge, old globular cluster is about 15,000 light years from
us, and is known for systems containing many interesting and strange stars.
Located in the southern
constellation of the Toucan, the cluster orbits our Milky Way. About 120 light
years across, is so great that, despite the distance, seems as big as the full
Moon. It houses billions of stars, is visible to the naked eye and is one of
the brightest globular clusters and the mass known. Among the jumble of stars
in the core are many intriguing systems, including X-ray sources, variable
stars, stars vampire, stars that shine blue stragglers unexpectedly in a
"normal", and tiny objects known as millisecond pulsars, small stars
Dead rotating at an incredible speed.
The red giant stars
that have exhausted their nuclear fuel and swell in size, are scattered in this
image taken by VISTA and are easily identifiable as a deep glowing amber
against the bright background of yellow and white stars. The compact core and
dense contrast to the outer regions of the cluster, more dispersed, and the
background can be seen numerous stars of the Small Magellanic Cloud.
This image was obtained
using ESO's VISTA (Visible and Infrared Survey Telescope for Astronomy) as part
of the VMC Survey is a survey of a region of the Magellanic Clouds, two of the
closest galaxies known. 47 Tucanae, despite being closer to the Clouds, is
casually between us and the Small Magellanic Cloud, and was captured during
this survey. The survey's principal investigator is Maria-Rosa Cioni,
University of Hertfordshire. Among the members associated with the project is
Dr. Andrew Piatti (UBA-IAFE).
VISTA is the world's
largest telescope dedicated to mapping the sky. Located at the ESO Paranal
Observatory in Chile, this infrared telescope, with its huge mirror, wide field
of view and very sensitive detectors, is revealing a new view of the southern
sky. Combining highly accurate infrared images - as shown below in VISTA - with
observations made in the visible range, astronomers can investigate in great
detail the contents and history of objects as 47 Tucanae.
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