Image: Hubble looks into Terzan 7

February 17, 2014
Credit: NASA, ESA, and A. Sarajedini

Named after its discoverer, the French-Armenian astronomer Agop Terzan, this is the globular cluster Terzan 7—a densely packed ball of stars bound together by gravity. It lies just over 75,000 light-years away from us on the other side of our galaxy, the Milky Way. It is a peculiar cluster, quite unlike others we observe, making it an intriguing object of study for astronomers.

Evidence shows that Terzan 7 used to belong to a small galaxy called the Sagittarius Dwarf Galaxy, a mini-galaxy discovered in 1994. This galaxy is currently colliding with, and being absorbed by, the Milky Way, which is a monster in size when compared to this tiny one. It seems that this has already been kidnapped from its former home and now is part of our own galaxy.

Astronomers recently discovered that all the stars in Terzan 7 were born at around the same time, and are about eight billion years old. This is unusually young for such a cluster. The shared birthday is another uncommon property; a large number of , both in the Milky Way and in other galaxies, seem to have at least two clearly differentiated generations of stars that were born at different times.

Some explanations suggest that there is something different about clusters that form within , giving them a different composition. Others suggest that clusters like Terzan 7 only have enough material to form one batch of stars, or that perhaps its youthfulness has prevented it from yet forming another generation.

Explore further: Soft shells and strange star clusters

Related Stories

Soft shells and strange star clusters

October 10, 2013

The beautiful, petal-like shells of galaxy PGC 6240 are captured here in intricate detail by the NASA/ESA Hubble Space Telescope, set against a sky full of distant background galaxies. This cosmic bloom is of great interest ...

Looking back to the cradle of our universe

February 10, 2014

(Phys.org) —NASA's Spitzer and Hubble Space Telescopes have spotted what might be one of the most distant galaxies known, harkening back to a time when our universe was only about 650 million years old (our universe is ...

Alien invaders pack the Milky Way

February 23, 2010

(PhysOrg.com) -- Around a quarter of the globular star clusters in our Milky Way are invaders from other galaxies, new research from Swinburne University of Technology (Australia) shows.

Video: Guide to our Galaxy

November 22, 2013

This virtual journey shows the different components that make up our home galaxy, the Milky Way, which contains about a hundred billion stars.

Recommended for you

SpaceX to launch classified US govt payload Sunday

April 29, 2017

SpaceX on Sunday is scheduled to make its first military launch, with a classified payload for the National Reconnaissance Office, which makes and operates spy satellites for the United States.

Is dark matter 'fuzzy'?

April 28, 2017

Astronomers have used data from NASA's Chandra X-ray Observatory to study the properties of dark matter, the mysterious, invisible substance that makes up a majority of matter in the universe. The study, which involves 13 ...

Hubble's bright shining lizard star

April 28, 2017

In space, being outshone is an occupational hazard. This NASA/ESA Hubble Space Telescope image captures a galaxy named NGC 7250. Despite being remarkable in its own right—it has bright bursts of star formation and recorded ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.