globular clusters Archives

November 29, 2024November 29, 2024 by Mark Thompson

Globular Clusters Evolve in Interesting Ways Over Time

Image gallery of the 16 globular clusters analysed in order of difference in the kinematic properties observed between the multiple stellar populations. Credits: ESA/Hubble - ESO - SDSS

Globular clusters are among the oldest objects in the Universe. The early Universe was filled with dwarf galaxies and its just possible that globular clusters are the remains of these ancient relics. Analysis of the stars in the clusters reveals ages in the region of 12-13 billion years old. A new paper just published shows that the globular clusters are home to two distinct types of stars; the primordial ones with normal chemical composition and those with unusual heavy amounts of heavier elements.

March 29, 2024March 29, 2024 by Evan Gough

The Milky Way’s Smallest, Faintest Satellite Galaxy Found

Hidden in this deep sky image (left) is Uma3/U1, an ultra faint galaxy. It contains fewer than 100 hundred stars, a tiny amount for a galaxy. Credit: CFHT/S. Gwyn (right) / S. Smith (left)

The Milky Way has many satellite galaxies, most notably the Large and Small Magellanic Clouds. They’re both visible to the naked eye from the southern hemisphere. Now astronomers have discovered another satellite that’s the smallest and dimmest one ever detected. It may also be one of the most dark matter-dominated galaxies ever found.

October 13, 2023October 13, 2023 by Jon Voisey

The Milky Way’s Stolen Globular Clusters

Modern astronomy holds that all major galaxies (with the Milky Way as no exception) are the accumulation of numerous small mergers. Thus, it should be expected that some of the globular clusters that are now part of our galaxy are likely inherited from other galaxies which have been cannibalized by the Milky Way, or even stolen from intact companion galaxies such as the Magellanic Clouds.

Associations between these clusters and the various progenitors began in the 1990’s, but recent research is beginning to paint a more comprehensive picture on exactly what percentage of our globular clusters were stolen, and precisely which ones.

September 12, 2023September 12, 2023 by Evan Gough

The Hubble Imaged Some Globular Clusters in an Unusual Place: Near the Milky Way’s Centre

Most globular clusters are found in the Milky Way's halo. But some, like the glittering globular cluster Terzan 12, are near the galactic centre. Image Credit: ESA/Hubble & NASA, R. Cohen (Rutgers University)

Our galaxy has about 200 Globular Clusters (GCs,) and most of them are in the galaxy’s halo. Astronomers think most GCs were taken from dwarf galaxies and merged with the Milky Way due to the galaxy’s powerful gravity. That explains why so many of them are on the outskirts of the galaxy. But they’re not all in the halo. Some are towards the Milky Way’s galactic bulge. What are globular clusters doing there?

February 13, 2023February 13, 2023 by Evan Gough

Globular Star Clusters are Constantly Kicking Stars out of the Galaxy

Omega Centauri is the brightest globular cluster in the night sky. It holds about 10 million stars and is the most massive globular cluster in the Milky Way. It's possible that globulars and nuclear star clusters are related in some way as a galaxy evolves. Image Credit: ESO.

All the stars we can see with the naked eye are part of the Milky Way. The gravitational power of the galaxy’s combined mass binds the stars to the galaxy. But sometimes stars are evicted from the galaxy.

These stars are called hypervelocity stars, and some of them are born from powerful gravitational interactions in globular clusters.

January 9, 2023January 9, 2023 by Evan Gough

The JWST is the Shiny New Space Telescope, but the Dependable Hubble is Still Going Strong

The scattered stars of the globular cluster NGC 6355 are strewn across this image from the NASA/ESA Hubble Space Telescope. This globular cluster lies less than 50,000 light-years from Earth in the Ophiuchus constellation. Image Credit: ESA/Hubble & NASA, E. Noyola, R. Cohen

The Venerable Hubble Space Telescope has cemented its place in history. Some call it the most successful science experiment ever. And while the James Webb Space Telescope might vie for that title, the Hubble does things that even the powerful JWST can’t do.

Exhibit A: this stunning image of NGC 6355.

December 3, 2022December 3, 2022 by Evan Gough

How Do Stars Get Kicked Out of Globular Clusters?

Hubble image of Messier 54, a globular cluster located in the Sagittarius Dwarf Galaxy. Credit: ESA/Hubble & NASA

Globular clusters are densely-packed collections of stars bound together gravitationally in roughly-shaped spheres. They contain hundreds of thousands of stars. Some might contain millions of stars.

Sometimes globular clusters (GCs) kick stars out of their gravitational group. How does that work?

November 30, 2022November 30, 2022 by Nancy Atkinson

Two Great Globular Clusters Seen by Hubble: Pismis 26 and Ruprecht 106

Pismis 26, a globular star cluster located about 23,000 light-years away, as seen by the Hubble Space Telescope. Credit: NASA, ESA and R. Cohen (Rutgers the State University of New Jersey); Processing: Gladys Kober (NASA/Catholic University of America).

If you like shiny things, some of the most gorgeous objects in space are globular clusters, with their bright, densely packed collections of gleaming stars. And if you like globular clusters, you’re in luck: two different Hubble images of globular clusters were featured this week by NASA and ESA.

August 8, 2022August 8, 2022 by Nancy Atkinson

Hubble can Still Impress and Inspire. Here's Globular Star Cluster NGC 6638

Globular cluster NGC 6638 in the constellation Sagittarius, as seen by the Hubble Space Telescope. Credit: ESA/Hubble & NASA, R. Cohen.

Wow, what a beauty! While we’ve all turned our attentions to the new James Webb Space Telescope, this image proves Hubble has still has got it where it counts.

This new image from the Hubble Space Telescope shows the heart of the globular cluster NGC 6638 in the constellation Sagittarius. This star-studded cluster contains tens of thousands to millions of stars, all tightly bound together by gravity. Globular clusters have a higher concentration of stars towards their centers, and this observation highlights that density.

October 20, 2021October 20, 2021 by Evan Gough

The Large Magellanic Cloud Stole one of its Globular Clusters

The Milky Way with the Small and Large Magellanic Clouds on the left. Image Credit: ESO/Y. Beletsky. CC 4.0

Astronomers have known for years that galaxies are cannibalistic. Massive galaxies like our own Milky Way have gained mass by absorbing smaller neighbours.

Now it looks like smaller galaxies like the Large Magellanic Cloud have also feasted on smaller neighbours.