The Hubble Space Telescope is treating us to yet another memorable snapshot of our galactic neighborhood. This time, Hubble has captured a massive globular cluster known as NGC 6139 — home to some of the oldest stars in the Milky Way.
Released on June 29 by the European Space Agency (ESA), the Hubble image reveals NGC 6139 — a "rich and dense smattering of stars" — as seen around the direction of our galaxy's center, in the Scorpius constellation (the Scorpion).
According to ESA, "this constellation is a goldmine of fascinating astronomical objects" and has yielded a great deal of jaw-dropping telescope footage. For instance, almost a decade ago, Hubble peered into the Scorpius constellation and snapped a stunning photo of the Butterfly Nebula, notes Hubblesite.com.
This latest image portrays just one of the many globular clusters imaged by Hubble during its 30 years of mapping out the sky. These dazzling features are defined as spherical collections of stars and orbit the core of a galaxy similar to a satellite.
Globular clusters — named after "globulus," the Latin word for "sphere" — are thought to exist in every galaxy in various numbers, ranging from a few hundred to several thousand in the case of giant elliptical galaxies.
The Milky Way boasts at least 150 globular clusters, reports Sci News, each of them tightly bound together by gravity and sporting a high density of stars, especially toward their center.
Packed with hundreds of thousands of stars, these globular clusters were "formed very early in the galaxy's history," although their exact role in the evolution of the Milky Way remains unclear.
Of all the globular clusters circling our galaxy's core, NGC 6139 is remarkably interesting. Discovered in 1826 by Scottish astronomer James Dunlop, this globular cluster, located some 35,000 light-years, is described by ESA as "an ageing beauty."
Space agency officials explain why.
"Studies have shown that this globular cluster, named NGC 6139, is home to an aging population of stars. Most globular clusters orbiting the Milky Way are estimated to be over 10 billion years old; as a result, they contain some of the oldest stars in our galaxy."The main difference between globular clusters and open star clusters, such as the famous Pleiades, is that they are much older and denser than the latter, while also residing in the galaxy's halo — as opposed to the galactic disk, where open star clusters are typically found.
The newly released image was taken by Hubble's Wide-Field Camera 3 (WFC3) instrument and is actually a composite of separate exposures that were initially monochromatic. As Sci News points out, the resulting photo owes its beautiful colors to the different hues assigned to each of the filters that were used to sample various wavelengths.