Stunning new images released this week by the European Southern Observatory (ESO) and the Hubble Space Telescope show globular star clusters in spectacular detail.
Globular clusters are spherical groups of over hundreds of thousands of ancient stars pulled toward each other by gravity. They are amongst the oldest objects in the universe, and for many years astronomers have used them to study the structure and evolution of stars.
Globular clusters are very common; our galaxy alone has about 150 million visible clusters orbiting its periphery, and many remained undiscovered.
This wide view of the globular star cluster NGC 6362 was captured by the 67-million pixels Wide Field Imager (WFI) attached to the MPG/ESO 2.2-metre telescope at La Silla Observatory in Chile. This is one of many new color images created from data obtained during the ESO Imaging Survey concluded in 2002.
Wide view of NGC 6362 captured by the Wide Field Imager in MPG/ESO 2.2-metre telescope (credit: European Southern Observatory)
This survey collected images of several regions of the sky in preparation for observations with the new huge Very Large Telescope (VLT). ‘The full set of data obtained by the ESO Imaging Survey would be better compared to a set of maps’ says Richard Hook, ESO’s public information officer.
Another dazzling image of NGC 6362 was created combining ultraviolet, visible-light and infrared images taken by the Hubble Space Telescope- a space-based observatory run by the European Space Agency and NASA.
|Detailed view of the NGC 6362 core captured by the Hubble Space Telecope (credit: European Space Agency/NASA)|
This view takes a closer look at the compact core of the globular cluster. Hook says ‘[Research] groups are combining WFI and Hubble data on globular clusters very successfully in other projects.’ The wide-angle and detailed views from these two telescopes ‘complement each other perfectly’.
Most stars in a globular cluster are over 10 billion years old, nearly as old as the universe itself, and they look typically yellowish or red. In recent years, however, younger-looking massive blue stars- blue stragglers- have been found in the core regions of star clusters, including NGC 6362.
Since all stars in a globular cluster were presumably born at the same time and therefore have similar ages, astronomers came up with two theories to explain blue stragglers: they must be the result of a star collision or a transfer of material between two neighboring stars.
The Paranal platform of the Very Large Telescope (VLT) with the four main units and four auxiliary telescopes (credit: ESO/H.H.Heyer)
The new images from ESO’s WFI/2.2-meter and Hubble telescopes will help astronomers from over 25 countries solve this and many other mysteries.
It will be exciting to see new answers and questions arise with the new generation of powerful super-telescopes like the VLT.