Tonight's Sky
Sun
Sun
Moon
Moon
Mercury
Mercury
Venus
Venus
Mars
Mars
Jupiter
Jupiter
Saturn
Saturn

Tonight's Sky — Change location

OR

Searching...

Tonight's Sky — Select location

Tonight's Sky — Enter coordinates

° '
° '

The tumultuous heart of our galaxy

A new XMM-Newton image shows the powerful remnants of dead stars and their mighty action on the surrounding gas near the Milky Way’s center.
X-ray view of the galactic center
The central regions of our galaxy, the Milky Way, seen in X-rays by ESA’s XMM-Newton X-ray observatory.

This image portrays powerful remnants of dead stars and their mighty action on the surrounding gas, showing us an unprecedented view of the Milky Way's energetic core. It was put together in a new study by compiling all observations of this region that were performed with XMM-Newton, adding up to over one month of monitoring in total.

The image combines data collected at energies from 0.5 to 2 keV (shown in red), 2 to 4.5 keV (shown in green) and 4.5 to 12 keV (shown in blue). It spans about 2.5º across, equivalent to about one thousand light-years.
ESA/XMM-Newton/G. Ponti et al. 2015
This new image of powerful remnants of dead stars and their mighty action on the surrounding gas from the European Southern Agency’s (ESA) XMM-Newton X-ray observatory reveals some of the most intense processes taking place at the center of our Milky Way Galaxy.

The bright, point-like sources that stand out across the image trace binary stellar systems in which one of the stars has reached the end of its life, evolving into a compact and dense object — a neutron star or black hole. Because of their high densities, these compact remnants devour mass from their companion star, heating the material up and causing it to shine brightly in X-rays.

The central region of our galaxy also contains young stars and stellar clusters, and some of these are visible as white or red sources sprinkled throughout the image, which spans about one thousand light-years.

Most of the action is occurring at the center where diffuse clouds of gas are being carved by powerful winds blown by young stars, as well as by supernovae, the explosive demise of massive stars.

The supermassive black hole sitting at the center of the galaxy is also responsible for some of this action. Known as Sagittarius A*, this black hole has a mass a few million times that of our Sun, and it is located within the bright fuzzy source to the right of the image center.

While black holes themselves do not emit light, their immense gravitational pull draws in the surrounding matter that, in the process, emits light at many wavelengths, most notably X-rays. In addition, two lobes of hot gas can be seen extending above and below the black hole.

Astronomers believe that these lobes are caused either directly by the black hole, which swallows part of the material that flows onto it but spews out most of it, or by the cumulative effect of the numerous stellar winds and supernova explosions that occur in such a dense environment.
The galactic center heavy elements
The central regions of our galaxy, the Milky Way, seen in X-rays by ESA’s XMM-Newton X-ray observatory.

This image portrays powerful remnants of dead stars and their mighty action on the surrounding gas, showing us an unprecedented view of the Milky Way's energetic core. It was put together in a new study by compiling all observations of this region that were performed with XMM-Newton, adding up to over one month of monitoring in total.

The image combines data collected at energies that correspond to the light emitted by heavy elements such as silicon and argon, which are produced primarily in supernova explosions, as well as other narrow energy bands. It spans about 2.5º across, equivalent to about one thousand light-years.
ESA/XMM-Newton/G. Ponti et al. 2015
This image, showing us an unprecedented view of the Milky Way's energetic core, was put together in a new study by compiling all observations of this region that were performed with XMM-Newton, adding up to about one and a half months of monitoring in total.

The large elliptical structure to the lower right of Sagittarius A* is a super-bubble of hot gas, likely puffed up by the remnants of several supernovae at its center. While this structure was already known to astronomers, this study confirms for the first time that it consists of a single gigantic bubble rather than the superposition of several individual supernova remnants along the line of sight.

Another huge pocket of hot gas, designated the “Arc Bubble” due to its crescent-like shape, can be seen close to the image center, to the lower left of the supermassive black hole. It is being inflated by the forceful winds of stars in a nearby stellar cluster, as well as by supernovae; the remnant of one of these explosions, a candidate pulsar wind nebula, was detected at the core of the bubble.

The rich data set compiled in this study contains observations that span the full range of X-ray energies covered by XMM-Newton; these include some energies corresponding to the light emitted by heavy elements such as silicon, sulphur, and argon, which are produced primarily in supernova explosions. By combining these additional information present in the data, the astronomers obtained another complementary view of the galactic center, which reveals beautifully the lobes and bubbles described earlier on.

In addition, this alternative view also displays the emission, albeit very faint, from warm plasma in the upper and lower parts of the image. This warm plasma might be the collective macroscopic effect of outflows generated by star formation throughout this entire central zone.

Another of the possible explanations for such emission links it to the turbulent past of the now not-so-active supermassive black hole. Astronomers believe that, earlier on in the history of our galaxy, Sagittarius A* was accreting and ejecting mass at a much higher rate, like the black holes found at the center of many galaxies, and these diffuse clouds of warm plasma could be a legacy of its ancient activity.
0

JOIN THE DISCUSSION

Read and share your comments on this article
Comment on this article
Want to leave a comment?
Only registered members of Astronomy.com are allowed to comment on this article. Registration is FREE and only takes a couple minutes.

Login or Register now.
0 comments
ADVERTISEMENT

FREE EMAIL NEWSLETTER

Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter.

ADVERTISEMENT
ADVERTISEMENT
asy_gravitational_eguide

Click here to receive a FREE e-Guide exclusively from Astronomy magazine.

Find us on Facebook