spaceSpace and Physics

This Is What The Center Of The Milky Way Looks Like


Jonathan O'Callaghan

Senior Staff Writer

1970 This Is What The Center Of The Milky Way Looks Like
An X-ray image of a portion of the Milky Way. ESA/XMM-Newton/G. Ponti et al. 2015.

These images reveal a remarkable view of some of the events taking place in the Milky Way – and show their effects on their surroundings. The mosaic images, which span 1,000 light-years across, were compiled from a month’s worth of X-ray data from ESA’s XMM-Newton X-ray observatory, which orbits Earth.

The data was gathered by astronomers at the Max Planck Institute for Extraterrestrial Physics in Germany for the Galactic Center XMM-Newton monitoring project, and published in the Monthly Notice of the Royal Astronomical Society.


The most obvious feature is the bright, cloudy region towards the middle-right of the image, which is the center of the Milky Way. The cause of this region is two-fold. First, powerful winds from young stars and supernovae are carving out clouds of gas. Second, our galaxy’s supermassive black hole – Sagittarius A* – is located at the center of this fuzzy region.

With a mass a few million times that of the Sun, the huge gravitational pull of Sagittarius A* is drawing in matter from its surroundings. This process is releasing large amounts of X-rays, making it comparatively “bright” in the image. Above and below the black hole are two lobes of gas, which are being thrown out by the black hole.

To the lower right of Sagittarius A*, a super-bubble of hot gas in an elongated shape can be seen. This is thought to have been formed by several supernovae. This bubble was already known to exist, but this proves that it's a single bubble, rather than several superimposed on top of each other.

Elsewhere in the image are plenty of other small dots. These are binary stellar systems where one star has reached the end of its life, and become a neutron star or black hole. The high density of these objects mean they devour a lot of mass from their companions, producing vast amounts of X-rays as they superheat incoming material.


This image shows X-rays produced by heavy elements. ESA/XMM-Newton/G. Ponti et al. 2015.

Another image, seen above, was compiled by measuring the X-ray emissions from heavy elements including silicon, sulfur and argon. These mostly originate from stars exploding as supernovae. In the image, the lobes from the black hole and the super-bubble can more clearly be seen.

In this second image, faint emission from “warm plasma” can also be seen at the top and bottom of the image in red. This plasma is thought to originate from stellar formation at the center of the Milky Way, or alternatively, it may be a remnant of a time when Sagittarius A* was more active in its distant past.

Aside from all that though, the images are also just fascinating to look at, especially when you consider that at each point source of light, there is an extremely energetic event taking place that is pouring out X-rays.


spaceSpace and Physics
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