Hubble Space Telescope Zooms in on Terzan 4

by johnsmith

This new image from the NASA/ESA Hubble Space Telescope shows a densely packed, crowded field of stars in the center of the globular cluster Terzan 4.

This Hubble image shows Terzan 4, a globular cluster some 26,100 light-years away in the constellation of Scorpius. Image credit: NASA / ESA / Hubble / R. Cohen.

This Hubble image shows Terzan 4, a globular cluster some 26,100 light-years away in the constellation of Scorpius. Image credit: NASA / ESA / Hubble / R. Cohen.

Globular clusters are systems of very ancient stars, gravitationally bound into a single structure about 100-200 light-years across.

They contain hundreds of thousands or perhaps a million stars. The large mass in the rich stellar center of a cluster pulls the stars inward to form a ball of stars. The word globulus, from which these clusters take their name, is Latin for small sphere.

Globular clusters are among the oldest known objects in the Universe and are relics of the first epochs of galaxy formation.

It is thought that every galaxy has a population of globular clusters. Some, like the Milky Way, have a few hundred, while elliptical galaxies can have several thousand.

“The launch of Hubble in 1990 revolutionized the study of globular clusters,” Hubble astronomers said.

“The individual stars in these dense crowds are almost impossible to distinguish from one another with ground-based telescopes, but can be picked apart using space telescopes.”

“Astronomers have taken advantage of Hubble’s crystal-clear vision to study the stars making up globular clusters, as well as how these systems change over time.”

The new Hubble image, composed of observations from Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3), shows the globular cluster Terzan 4.

This group of stars is located approximately 8,000 parsecs (26,100 light-years) away in the constellation of Scorpius.

Otherwise known as Haute-Provence 4 and GCl 66.1, it was first discovered by the French astronomer Agop Terzan in 1968.

Terzan 4 resides in a crowded and metal-rich environment of the Milky Way’s bulge.

“This particular observation comes from astronomers using Hubble to explore Terzan 4 and other globular clusters to understand the shape, density, age, and structure of globular clusters close to the center of the Milky Way,” the researchers explained.

“Unlike globular clusters elsewhere in the sky, these globular clusters have evaded detailed observation because of the clouds of gas and dust swirling around the galactic core.”

“These clouds blot out starlight in a process that astronomers refer to as ‘extinction,’ and complicate astronomical observations.”

“The astronomers took advantage of Hubble’s ACS and WFC3 instruments to overcome the impact of extinction on Terzan 4.”

“By combining Hubble imagery with sophisticated data processing, they were able to determine the ages of galactic globular clusters to within a billion years — a relatively accurate measurement in astronomical terms!”

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