AAO image reference UKS 30a. « Previous || Next »
Top left is NE. Image width is about 2 degrees
Image and text © 1993-2010, Australian Astronomical Observatory.
Photograph from UK Schmidt plates by David Malin.
Antares is a giant among stars, and like giants in general, very rare. Antares is about 600 light years away in the direction of Scorpius. It is a first magnitude star 15 times more massive than the Sun and tens of thousands of time more luminous. It has spent most of its short life as a blue supergiant star, its mass obliging it to consume its vast store of nuclear fuel (hydrogen) very rapidly. This nuclear fusion process supplied the energy that prevented the star collapsing in on itself -- all stars support themselves against gravity in this way. Now, the supply of fuel in the core of the star is close to exhaustion and the star has undergone a major internal re-arrangement to cope with the changed circumstances, both cooling and swelling in the process. It has become a red supergiant.
This star is big, about 700 times the diameter of the Sun. If Antares were to replace the Sun in the solar system, both the Earth and Mars would be inside the distended atmosphere of the star. At its cool surface, tiny solid particles begin to appear, made from traces of heavier elements formed inside the star. In this photograph the tiny dust grains drift away, reflecting Antares' yellowish light and making the wispy nebula that seems to envelop the moribund star, soon to be a supernova. In the background, seen through the nebula is a globular cluster, NGC 6144, over 30,000 light years away, while much brighter and closer is the globular cluster M4, NGC 6121, about 7,200 light years distant.
UKS 4. Antares and the Rho Ophiuchi dark cloud
UKS 30. NCG 6144 and the nebula around Antares
Constellation of Scorpius (external site)
For details of object position and photographic exposure, search technical table by UKS reference number.
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