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Video: Mystery X-ray source in distant galaxy

SINCE THE 1980s, astronomers have known about a mysterious class of objects that they call “ultraluminous X-ray sources,” or ULXs. They named them this because these objects give off more X-rays than most other binary star systems where black holes or neutron stars are in orbit around a normal companion star.

Recently, scientists using NASA’s Chandra X-ray Observatory and optical telescopes spotted a ULX in the spiral galaxy M83 that was acting even more strangely. This ULX increased its output in X-rays by 3,000 times over the course of several years.

Using clues found in the X-ray and optical data, researchers think this ULX may be a member of a population of black holes that up until now was suspected to exist but had not been confirmed.

These black holes, which are the smaller stellar-mass black holes (ones that form from the collapse of a giant star), are older and more active than previously thought.

Video courtesy NASA / CXC. Image close-ups – X-ray, NASA / CXC / Curtin University / R. Soria et al.; optical, NASA / STScI / Middlebury College / F. Winkler et al.

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Spiral galaxy M83

Image of the nearby galaxy Messier 83

This image of the nearby galaxy Messier 83 was taken in the infrared part of the spectrum with the HAWK-I instrument on ESO’s Very Large Telescope, revealing vast numbers of stars within the galaxy.

  • 15 million light-years away
  • 40 percent the size of the Milky Way
  • Home to 6 recently spotted exploding stars

The European Southern Observatory (ESO) has released a beautiful image of the nearby galaxy Messier 83 taken by the HAWK-I instrument on ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile.

The picture shows the galaxy in infrared light and demonstrates the impressive power of the camera to create one of the sharpest and most detailed pictures of Messier 83 ever taken from the ground.

Messier 83 is about 15 million light-years away. It is over 40,000 light-years wide, only 40 percent the size of the Milky Way, but in many ways is quite similar to our home galaxy, both in its spiral shape and the presence of a bar of stars across its centre.

The galaxy is famous among astronomers for its many supernovae: vast explosions that end the lives of some stars. Over the last century, six supernovae have been spotted in Messier 83 — a record number that is matched by only one other galaxy.

Comparison of the view of the galaxy Messier 83 in infrared and visible light.

Comparison of the view of the galaxy Messier 83 at infrared light wavelengths (left) and at visible light wavelengths (right). In the infrared, the dust that obscures many stars becomes nearly transparent, making the spiral arms seem less dramatic, but revealing a whole host of new stars that are otherwise invisible.

Even without supernovae, Messier 83 is one of the brightest nearby galaxies, visible using just binoculars.

When viewed in infrared light by HAWK-I, most of the obscuring dust that hides much of Messier 83 becomes transparent. The brightly lit gas around hot young stars in the spiral arms is also less prominent in infrared pictures. As a result much more of the structure of the galaxy and the vast hordes of its constituent stars can be seen.

This clear view is important for astronomers looking for clusters of young stars, especially those hidden in dusty regions of the galaxy. Studying such star clusters was one of the main scientific goals of these observations. The acute vision of HAWK-I reveals far more stars within the galaxy.

Adapted from information issued by ESO / M. Gieles / Mischa Schirmer.