Credit: ESA/Hubble & NASA, R. Cohen
This scintillating image showcases the globular cluster NGC 6540 in the constellation Sagittarius, which was captured by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 and Advanced Camera for Surveys.
These two instruments have slightly different fields of view — which
determines how large an area of sky each instrument captures. This
composite image shows the star-studded area of sky that was captured in
both instruments’ field of view.
NGC 6540 is a globular cluster, a stable, tightly bound multitude of stars.
The populations of these clusters can range from tens of thousands to
millions of stars, all of which are trapped in a closely-packed group by
their mutual gravitational attraction.
The brightest stars in this image are adorned with prominent
cross-shaped patterns of light known as diffraction spikes. These
astronomical embellishments are a type of imaging artefact, meaning that
they are caused by the structure of Hubble rather than the stars
themselves. The path taken by the starlight as it enters the telescope
is slightly disturbed by its internal structure, causing bright objects
to be surrounded by spikes of light.
Hubble peered into the heart of NGC 6540 to help astronomers measure
the ages, shapes, and structures of globular clusters towards the centre
of the Milky Way. The gas and dust shrouding the centre of our galaxy
block some of the light from these clusters, as well as subtly changing
the colours of their stars. Globular clusters contain insights into the
earliest history of the Milky Way, and so studying them can help
astronomers understand how our galaxy has evolved.
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Source: ESA/Hubble/potw
