'Ghost' cluster may reveal Milky Way's origin

A unique star cluster is a remnant of the earliest days of the Milky Way, as analyzed by a team of astronomers.

Washington DC: A team of astronomers has analyzed a unique star cluster they say is a remnant of the earliest days of the Milky Way.

When our galaxy was born, around 13,000 million years ago, a plethora of clusters containing millions of stars emerged. But over time, they have been disappearing. However, hidden behind younger stars that were formed later, some old and dying star clusters remain, such as the so-called E 3. European astronomers have now studied this testimony to the beginnings of our galaxy.

Globular clusters are spherical-shaped or globular stellar groupings, hence its name- which can contain millions of stars. There are about 200 of them in the Milky Way, but few are as intriguing to astronomers as the E 3 cluster.

It is situated around 30,000 light years away, in the southern constellation of Chameleon. The team of Spanish and Italian astronomers has named it "a ghost from the Milky Way's past" in an article published recently in the Astronomy & Astrophysics journal.

"This globular cluster, and a few similar ones, such as Palomar 5 or Palomar 14, are 'ghosts' because they appear to be in the last stages of their existence, and we say 'from the past' because they are very old. They were formed when our galaxy was virtually new-born, 13,000 million years ago," says one of the authors Carlos de la Fuente Marcos.

According to another study on E 3 by Michigan State University (USA) researchers, published in The Astrophysical Journal, this cluster is chemically homogeneous, that is, it doesn't have several star populations in its interior.

"We hope to obtain new data in 2016, thanks to more spectroscopic observations, and perhaps we will be able to give answers to these questions," says De la Fuente Marcos.