globular clusters Archives

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. Image Credit: By ESO - https://www.eso.org/public/images/eso0844a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=6283919

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.

September 28, 2021September 28, 2021 by Nancy Atkinson

No News Here, Just a Beautiful Globular Cluster Captured by Hubble. That is all.

Globular cluster ESO-520-21 as seen by Hubble. Credit: NASA/ESA/Hubble.

Here’s some beauty for your timeline: a stunning and ancient globular cluster captured by the venerable Hubble Space Telescope. The telescope’s Wide Field Camera 3 and Advanced Camera for Surveys was used to take this picture of ESO 520-21 (also known as Palomar 6), which is located about 25,000 light years away from Earth. Scientists say this globular cluster is probably about 12.4 billion years old.

February 15, 2021February 15, 2021 by Brian Koberlein

A Cluster of Black Holes Found Inside a Globular Cluster of Stars

This image from the NASA/ESA Hubble Space Telescope shows the central region of the rich globular star cluster NGC 3201 in the southern constellation of Vela (The Sails). A star that has been found to be orbiting a black hole with four times the mass of the Sun is indicated with blue circle. Credit: ESA/NASA

Black holes come in at least two sizes: small and large. Small black holes are formed from stars. When a large star reaches the end of its life, it typically ends in a supernova. The remnant core then collapses under its own weight, forming a black hole or neutron star. Small stellar-mass black holes are typically tens of solar masses. Large black holes lurk in the centers of galaxies. These supermassive black holes can be millions or billions of solar masses. They formed during the early universe and triggered the formation and evolution of galaxies around them.

October 7, 2020October 7, 2020 by Evan Gough

7% of the Stars in the Milky Way’s Center Came From a Single Globular Cluster That Got Too Close and Was Broken Up

Central region of the Milky Way in infrared light. With this image, NASA's Spitzer Space Telescope has photographed the inner 890 x 640 light years of the Milky Way. The nuclear star cluster is located in a small area near the central massive black hole. The extended structures in the image are mostly clouds of gas and dust from the spiral arms of the Milky Way, which lie in the line of sight between Earth and the Galactic Centre. Image Credit: NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center/Caltech)

The heart of the Milky Way can be a mysterious place. A gigantic black hole resides there, and it’s surrounded by a retinue of stars that astronomers call a Nuclear Star Cluster (NSC). The NSC is one of the densest populations of stars in the Universe. There are about 20 million stars in the innermost 26 light years of the galaxy.

New research shows that about 7% of the stars in the NSC came from a single source: a globular cluster of stars that fell into the Milky Way between 3 and 5 billion years ago.