A black hole named V404 Cygni, one of the closest to our planet, spent 25 years sitting relatively quietly, producing very little activity. But in June last year it broke its silence with a bright and violent outburst. A team of scientists started to watch the black hole after it began its outburst, and the results have now revealed it was giving off an intense wind of hydrogen and helium. Scroll down for video
Artistic view of the accretion disc surrounding the black hole V404 Cygni, where the intense wind detected by GTC becomes evident. The black hole spent 25 years sitting quietly until June last year when it broke its silence with a bright and violent outburst In June 2015, V404 Cygni erupted 7,800 light years away and gave off material from a neighbouring star that it could not swallow. During this time its brightness increased one million fold in a few days, becoming the brightest X-ray source in the sky.
It was one of the brightest black hole outbursts seen in recent years and made the black hole brighter for about two weeks. The team of astrophysicists, including Professor Phil Charles from the University of Southampton, began taking optical measurements of the black hole's accretion disc using the biggest optical telescope in the world, the 34ft (10.4 metre ) Gran Telescopio Canarias (GTC) in the Canary Islands.
Astrophysicists took measurements with the biggest optical telescope in the world, the 34ft (10.4m) Gran Telescopio Canarias (GTC) These events are notoriously difficult to capture since they are unpredictable and rare. This means astronomers are given little time to react. The GTC began taking spectroscopic observations on 17 June after a 'target of opportunity' programme, designed especially for this kind of event, was activated. The team saw a wind made up of hydrogen and helium coming out of V404 Cygni that had never been detected before in a black hole like this. The wind moved very quickly, covering 1,864 miles (3,000km) every second second, so it can escape the strong gravitational field around the black hole. At the end of the outburst the observations revealed the presence of a nebula formed from material expelled by the wind. It formed in the outer layer of the accretion disc. 'Its presence allows us to explain why the outburst, in spite of being bright and very violent, with continuous changes in luminosity and ejections of mass in the form of jets, was also very brief, lasting only two weeks,' said Professor Charles. An international team of astronomers reported that the black hole emitted red flashes lasting just fractions of a second, as it blasted out material that it could not swallow. Inset shows a red flash from V404 Cygni observed by the Ultracam on the William Herschel Telescope in the early morning hours of June 26, 2015
THE V404 CYGNI BLACK HOLE
The black hole, named V404 Cygni, is about 7,800 light years from Earth, and it was the first black hole in our galaxy to be seen. V404 Cygni is a microquasar and a binary system consisting of a black hole with a mass of about 12 solar masses and a companion star of mass slightly smaller than the sun. Due to their proximity, the star is distorted into egg shape by the black hole's gravity and loses mass to the black hole. V404 Cygni last erupted back in 1989. When it erupted in June 2015, it was one of the brightest in recent years. Most outbursts are far dimmer, making them difficult to study. This phenomenon, which has been observed for the first time in a black hole, also allows scientists to estimate the quantity of mass ejected into the interstellar medium - the vast space in between stars. Each flash was blindingly intense, equivalent to the power output of about 1,000 suns. 'The brightness of the source and the large collecting area allowed us not only to detect the wind, but also to measure the variation of its properties on time-scales of minutes,' said Teo Muñoz Darias, a researcher at the Instituto de Astrofísica de Canarias (IAC) and the lead author of the study. 'The database obtained is probably the best ever observed for an object of this kind.' 'This outburst of V404 Cygni, because of its complexity and because of the high quantity and quality of the observations, will help us understand how black holes swallow material via their accretion discs.' 'We think that what we have observed with the GTC in V404 Cygni happens, at least, in other black holes with large accretion discs,' said Professor Charles.
Subject: NASA/ Disney -BS- yet more 
Tue Apr 26, 2016 5:52 pm
