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Headlines Published on 12 January 2009

ASTRONOMY
Title Atlantic partnership emerges as Black hole tears matter

Astronomers from Europe and the USA have teamed together to study violent flares that are emanating from the supermassive black hole in the centre of the Milky Way. This is the first time that astronomers have simultaneously caught a flare with their special telescopes. In order to conduct simultaneous observations, careful planning and coordination is required between the two teams and their telescopes. Their observations will hopefully reveal a lot more about this intriguing sector in space.

Submillimetre and infrared view of the Galactic Centre © ESO
Submillimetre and infrared view of the Galactic Centre
© ESO

Deep in the depths of the Milky Way lies Sagittarius A, otherwise referred to as Sgr A. According to astronomers, this is a compact object approximately 26 000 light-years from Earth. Close observations of stars in this region have convincingly proven that Sagittarius A must be a supermassive black hole with a mass of about four million times that of the Sun.

Now astronomers from Europe and the USA have witnessed a flare emanating from the region of Sagittarius A. These flares are thought to be gas which is thrown off by stars. These flares however do not have the chance to travel far, such is the gravitational pull that they enter an orbit before being sucked back into the black hole.

As a result, astronomers with the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) have joined together with the Atacama Pathfinder Experiment (APEX) telescope to study light from Sagittarius A at near-infrared wavelengths and the longer sub millimetre wavelengths respectively.

Gunther Witzel, a PhD student from the University of Cologne in Germany commented from his station at ESO's Very Large Telescope (VLT). 'At the VLT, as soon as we pointed the telescope at Sagittarius A, we saw it was active and getting brighter by the minute. We immediately picked up the phone and alerted our colleagues at the APEX telescope,' he said.

Macarena García-Marín, also from Cologne, was waiting at APEX, where the observatory team had made a special effort to keep the instrument on standby. 'As soon as we got the call we were very excited and had to work really fast so as not to lose crucial data from Sagittarius A. We took over from the regular observations, and were in time to catch the flares,' she explains.

Over the next six hours, the team detected violently variable infrared emissions, with four major flares from Sagittarius A. The submillimetre-wavelength results also showed flares, but, crucially, this occurred about one and a half hours after the infrared flares.

According to the University of Cologne's Andreas Eckart, who led the team, 'Observations like this, over a range of wavelengths, are really the only way to understand what's going on close to the black hole.'

Both of these telescopes are located in Chile; their location in the southern hemisphere provides the best vantage point for studying the Galactic Centre. The simultaneous combination of the VLT and APEX telescopes has proved to be a powerful way to study the flares at multiple wavelengths. The team hopes that future observations will let them prove their proposed model, and discover more about this mysterious region at the centre of our Galaxy.









More information:

  • ESO
  • APEX telescope







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