Core Values

The core  of Messier 13 - COAST Robotic Telescope - telescope.org - Open University - Credit: Pip Stakkert

The core of the globular cluster Messier 13 is just 25 000 light-years away and measures about 145 light-years in diameter. It lies in the constellation Hercules and sometimes can even be seen with small binoculars. Credit: ESA / Hubble and NASA

This image, taken by the Advanced Camera for Surveys on the Hubble Space Telescope, shows the core of the great globular cluster Messier 13 and provides an extraordinarily clear view of the hundreds of thousands of stars in the cluster, one of the brightest and best known in the sky. Just 25 000 light-years away and about 145 light-years in diameter, Messier 13 has drawn the eye since its discovery by Edmund Halley, the noted British astronomer, in 1714. The cluster lies in the constellation of Hercules and is so bright that under the right conditions it is even visible to the unaided eye. As Halley wrote: “This is but a little Patch, but it shews it self to the naked Eye, when the Sky is serene and the Moon absent.” Messier 13 was the target of a symbolic Arecibo radio telescope message that was sent in 1974, communicating humanity’s existence to possible extraterrestrial intelligences. However, more recent studies suggest that planets are very rare in the dense environments of globular clusters.

Messier 13 has also appeared in literature. In his 1959 novel, The Sirens of Titan, Kurt Vonnegut wrote “Every passing hour brings the Solar System forty-three thousand miles closer to Globular Cluster M13 in Hercules — and still there are some misfits who insist that there is no such thing as progress.” The step from Halley’s early telescopic view to this Hubble image indicates some measure of the progress in astronomy in the last three hundred years.

This picture was created from images taken with the Wide Field Channel of the Advanced Camera for Surveys on the Hubble Space Telescope. Data through a blue filter (F435W) are coloured blue, data through a red filter (F625W) are coloured green and near-infrared data (through the F814W filter) are coloured red. The exposure times are 1480 s, 380 s and 567 s respectively and the field of view is about 2.5 arcminutes across. 

ESA/Hubble and NASA

(note the green channel data in the above image was reduced by Pip Stakkert at the Jodrell Plank Observatory)

The Hubble and the COAST widefield images were combined by Pip Stakkert to create a widefield image of the star cluster with improved star resolution to the core.

" The  Great Globular star cluster in Hercules is such a beautiful sight through the eyepiece of almost any telescope. It is however, very difficult to convey its beauty in a photograph. The very nature of the faint stars at the edge of one's eye to resolve, creates a stardust affect which is very difficult to describe and even more difficult to image. Messier 13 is almost as old as the universe but can still provide surprises - recent evidence suggests that M 13 has an axis of rotation and an extended stellar halo". - Kurt Thrust - acting CEO and current Director of the Jodrell Plank Observatory.

Credits: Phys.org and Max Plank Institute

" The Observatory will be offline for a couple of days as all the staff will be attending the march against BREXIT in London. We wish to protest against the betrayal of our country's best interests, as part of Europe and the Global Community, by the appalling performance of our Parliament and Government - 'The Clown Parliament led by Donkeys'" - Ivor Hump - Chair of the Board of Trustees - Jodrell Plank Observatory.