E-Paper
Black holes are 'green', says NASA
Scientists says the new findings give insight on how nine black holes generated their huge energy in space.
Black holes are the most fuel-efficient engines in the universe, the US space agency NASA said.
NASA scientists said on Monday that the new findings, using the agency's Chandra X-Ray Observatory, gave insight on how nine black holes generated their huge energy in space.
If a car were as fuel-efficient as these black holes, it would travel more than 1 billion miles (1.6 billion km) on one gallon (3.8 litres) of petrol, said Christopher Reynolds of the University of Maryland.
Black holes - former stars so massive that even light cannot escape them - also are 20 times more efficient than nuclear reactors, the study found.
The scientists said they calculated the size of the galaxies' inner regions to estimate how much "fuel" - gas in space that is drawn into the black holes - is available.
Then, the observatory's images were used to estimate how much power was developed by the resulting jets of high-energy particles to create huge bubbles, or cavities, in the galaxies' hot gas.
