Free Astronomy Magazine January-February 2015

SPACE CHRONICLES 4- to 29-megaparsecs, but using this new, more accurate method, the re- searchers calculated the distance to the supermassive black hole as 19 megaparsecs. The galaxy NGC 4151 is dubbed the ‘Eye of Sauron’ by astronomers for the similarity to its namesake in the film trilogy The Lord of the Rings. As in the famous saga, a ring plays a crucial role in this new measure- ment. All big galaxies in the universe host a supermassive black hole in their center and in about 10 percent of all galaxies, these supermassive black holes are growing by swallow- ing huge amounts of gas and dust from their surrounding environ- ments. In this process, the material heats up and becomes very bright — ‘Eye of Sauron’ provides new way of measuring distances to galaxies T he Galaxy NGC 4151 called the, ‘Eye of Sauron’ due to its similar- ity to the eye in the film “Lord of the Rings”. The image shows the su- permassive black hole, which is still active, that is to say that it engulfs gas and dust clouds from its sur- roundings. In this process, it emits ultraviolet radiation, which heats the ring-shaped dust cloud that or- bits around the black hole at a dis- tance and this causes the dust cloud to emit infrared radiation. [X-ray: NASA/CXC/CfA/J.Wang et al.; Optical: Isaac Newton Group of Telescopes, La Palma/Jacobus Kapteyn Tele- scope, Radio: NSF/NRAO/VLA] by Keck Observatory A team of scientists, led by Dr. Sebastian Hoenig from the University of Southampton, has accurately measured the distance to the nearby NGC 4151 galaxy, using the W. M. Keck Observatory Interfer- ometer. The team employed a new technique they developed, which al- lows them to measure precise dis- tances to galaxies tens of millions of light years away. The research was published in the journal Nature . The new technique is similar to that used by land surveyors on Earth, who measure both the physical and angu- lar – or ‘apparent’ – size of a distant object, to calculate its distance from Earth. Previous reported distances to NGC 4151, which contains a su- permassive black hole, ranged from