The Milky Way’s Nuclear Star Cluster

The most massive, densest star cluster in the galaxy 

In this image the infrared light, which is invisible to humans, has been translated into colors our eyes can see. The red stars observed are embedded or shrouded by intervening dust and gas. Areas appearing dark against the bright background stars are actually very dense clouds of gas and dust seen in silhouette. These regions even the infrared eyes of the Hubble Space Telescope can’t penetrate. Credits: NASA/ESA/Hubble

Space news (Into the lair of the Monster of the Milky Way) – the center of the galaxy, 27,000 light-years away – 

Astronomers recently used the Hubble Space Telescope’s infrared vision to observe the lair of the Monster of the Milky Way. Using Hubble’s infrared cameras scientists revealed a dusty galactic core crammed with over an estimated half a million stars. Plus at least ten million stars too faint to be seen by Hubble through the dust in the disk of our island universe. Watch this Spitzer Space Telescope site video “The Hidden Universe: The Galactic Center Revisited“.

A keyhole-view through Hubble’s looking glass towards the center of the Milky Way through the Sagittarius Star Cloud at a treasure chest full of stars. A treasure chest containing ancient stars that first formed the galaxy with a tale to tell astronomers about the evolution of galaxies.

Part of the Milky Way’s nuclear star cluster, the densest and most massive star cluster in the galaxy, these stars orbit Sagittarius A, a supermassive black hole astronomers believe resides at the center of our galaxy. Called the Monster of the Milky Way, the stars in this cluster are doomed to fall prey to this mysterious object, to be swallowed whole by this 4 million solar mass supermassive black hole. 

The 4-million-solar-mass black hole at the center of the Milky Way.

The bottom panel of this graphic is a view of the region around Sgr A* where red, green, and blue represent low, medium, and high-energy X-rays detected by NASA’s Chandra X-ray Observatory. Sgr A* itself is not visible in this image but is embedded in the white dot at the end of the arrow. The other two telescopes involved in the 15 years of X-ray observations were ESA’s XMM-Newton and NASA’s Swift Gamma Ray Burst Explorer, but their data are not included in this image.

Astrophysicists measured the movements of the stars within the galactic core to determine the mass and structure of the nuclear star cluster. Using these measurements they were able to get a glimpse backward in time to the moment it was formed. To see if it was constructed over time as globular clusters fell into the core of the galaxy or from gas and dust spiraling into the core from the disk to form new stars. 

This image is meant to show the grand scale of the lair of the Monster of the Milky Way. The storm of stars seen here is actually just the tip of the iceberg, there are at least 10 million stars in this image to faint for Hubble to detect according to estimates by astronomers. Astronomers used the Hubble Space Telescope’s infrared vision to look through the dust in the disk of the Milky Way at its nuclear star cluster. Credits: NASA/ESA/Hubble

Study continues

Astronomers weren’t able to determine which scenario best fits current theory and computer simulations conducted. They continue to modify parameters and devise additional scenarios to explain the formation of the nuclear star cluster. We’ll update you on their findings in future articles. 

Learn more about the Monster of the Milky Way – Sagittarius A

Discover NASA

Take the space journey of the ESA here

Read and learn more about the Milky Way’s nuclear star cluster

Read about the unusual star formation timescale astronomers have observed in dwarf galaxy Leo A.

Check out this artist’s conception of future Europa spacecraft.

Read about Chandra’s detection of X-rays emitted by a distant supermassive black hole.