Globular Cluster Archives

January 4, 2024January 4, 2024 by Evan Gough

This Globular Cluster is Plunging Toward the Milky Way’s Centre

The galactic cenre is dominated by powerful tidal forces. What happens to globular clusters that get too close? Image Credit: Spitzer Space Telescope/NASA/JPL-Caltech

Globular clusters (GCs) are spherical groups of stars held together by mutual gravity. Large ones can have millions of stars, and the stars tend to be older and have lower metallicity. The Milky Way contains more than 200 globulars, possibly many more, and most of them are in the galaxy’s halo, the outer reaches of the galaxy.

But they’re not all in the halo, and astronomers are keen to find ones nearest the galactic centre. Now, researchers have found one GC that’s plunging toward the Milky Way’s Centre.

May 23, 2023May 23, 2023 by Evan Gough

Where Are the Missing Black Holes? The Hubble May Have Helped Find One

This Hubble Space Telescope image shows the globular cluster Messier 4. It contains several hundre thousand stars, and its center might host an elusive intermediate-mass black hole. The black hole could have 800 solar masses. Image Credit: ESA/Hubble & NASA

Most black holes are stellar mass black holes. They’re created when a star several times more massive than our Sun reaches the end and collapses in on itself. There are also supermassive black holes (SMBH,) the behemoths at the center of galaxies that can boast billions of times more mass than the Sun.

But where are the intermediate-mass black holes?

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.

July 3, 2021July 3, 2021 by Matthew Cimone

The Center of the Milky Way is the Most Likely Place to Find a Galactic Civilization

Composite image of the Milky Way's core created by Hubble, Spitzer, and Chandra telescopes. Credit X-ray: NASA/CXC/UMass/D. Wang et al.; Optical: NASA/ESA/STScI/D.Wang et al.; IR: NASA/JPL-Caltech/SSC/S.Stolovy

Aim for the Center

The Milky Way is 13 BILLION years old. Some of our Galaxy’s oldest stars were born near the beginning of the Universe itself. During all these eons of time, we know at least one technological civilization has been born – US!

But if the Galaxy is so ancient, and we know it can create life, why haven’t we heard from anybody else? If another civilization was just 0.1% of the Galaxy’s age older than we are, they would be millions of years further along than us and presumably more advanced. If we are already on the cusp of sending life to other worlds, shouldn’t the Milky Way be teeming with alien ships and colonies by now?

Maybe. But it’s also possible that we’ve been looking in the wrong place. Recent computer simulations by Jason T. Wright et al suggest that the best place to look for ancient space-faring civilizations might be the core of the Galaxy, a relatively unexplored target in the search for extra terrestrial intelligence.

Animation showing the settlement of the galaxy. White points are unsettled stars, magenta spheres are settled stars, and white cubes represent a settlement ship in transit. The spiral structure formed is due to galactic shear as the settlement wave expands. Once the Galaxy’s center is reached, the rate of colonization increases dramatically. Credit: Wright et al

June 9, 2020June 9, 2020 by Evan Gough

Hubble Photo of Globular Cluster NGC 6441, One of the Most Massive in the Milky Way

NGC 6441 is one of the most luminous and massive globular clusters in the Milky Way. It also hosts fours pulsars. Image Credit: ESA/Hubble & NASA, G. Piotto

The Hubble Space Telescope has delivered another outstanding image. This one is of NGC 6441, a massive globular cluster in the constellation Scorpius. It’s one of the most massive ones in the Milky Way, and the stars in it have a combined mass of 1.6 million solar masses.

September 23, 2019December 2, 2019 by Tammy Plotner

Messier 92 – the NGC 6341 Globular Cluster

M92 by the Hubble Space Telescope. Credit: ESA/NASA

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the globular cluster known as Messier 92!

During the 18th century, famed French astronomer Charles Messier noticed the presence of several “nebulous objects” while surveying the night sky. Originally mistaking these objects for comets, he began to catalog them so that others would not make the same mistake. Today, the resulting list (known as the Messier Catalog) includes over 100 objects and is one of the most influential catalogs of Deep Space Objects.

One of these objects is Messier 92, a globular cluster located in the northern constellation of Hercules. This cluster lies at a distance of 26,700 light-years from Earth and is also approaching our galaxy at a speed of about 112 km/s (403,200 km/h; 250,500 mph) – which means it will eventually merge with our own. With an average estimated age of 14.2 billion years (± 1.2 billion years), it is almost as old as the Universe itself!

March 11, 2019December 2, 2019 by Tammy Plotner

Messier 80 – the NGC 6093 Globular Cluster

The globular cluster Messier 80. Credit: NASA/Hubble Heritage Team/STScI/ AURA

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the globular cluster known as Messier 80!

One of these objects is Messier 80, a globular star cluster located about 32,600 light years from Earth in the constellation Scorpius. This cluster is one of the most densely populated in our galaxy and is located about halfway between the bright stars Antares, Alpha Scorpii, Akrab and Beta Scorpii – making it relatively easy to find.

Continue reading “Messier 80 – the NGC 6093 Globular Cluster”

December 31, 2018January 14, 2019 by Tammy Plotner

Messier 75 – the NGC 6864 Globular Cluster

Hubble image of the globular cluster known as Messier 75. Credits: NASA, ESA, STScI, and G. Piotto (Università degli Studi di Padova) and E. Noyola (Max Planck Institut für extraterrestrische Physik)

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the globular cluster known as Messier 75!

One of these objects is Messier 75 (aka. NGC 6864), a globular cluster roughly 67,500 light years from Earth near the southern constellation Sagittarius. This object is also about 14,700 light years away from the Galactic Center, and on the located on the other side relative to Earth. Because of its distance and location, this object is virtually impossible to see binoculars and difficult to resolve with small telescopes. Continue reading “Messier 75 – the NGC 6864 Globular Cluster”

November 26, 2018November 26, 2018 by Tammy Plotner

Messier 72 – the NGC 6981 Globular Cluster

Messier 72 and Messier 73. Credit: Wikisky

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the globular cluster known as Messier 72.

One of these objects is Messier 72, a globular cluster about 54,570 light years away in the direction of the Aquarius constellation. Originally discovered by French astronomer Pierre Méchain a few years prior, Messier would go on to include this star cluster in his catalog. Located in close proximity to Messier 73, this globular cluster is one of the smaller and fainter Messier objects in the night sky. Continue reading “Messier 72 – the NGC 6981 Globular Cluster”

November 12, 2018November 12, 2018 by Tammy Plotner

Messier 71 – the NGC 6838 Globular Cluster

Chart showing the M71 Globular Cluster. Credit: astronomycentral.co.uk

Welcome back to Messier Monday! Today, we continue in our tribute to our dear friend, Tammy Plotner, by looking at the unusual globular cluster known as Messier 71.

If you look up into the night sky, on a particularly clear night when there’s not a lot of bright lights nearby, you may be able to make out a series of faint objects. Similar to the Milky Way, that cloudy, ghostly band that reaches across the night sky, these small pockets of fuzzy light are in fact collections of stars located thousands of light years away.

Continue reading “Messier 71 – the NGC 6838 Globular Cluster”