For the first time scientists have photographed this halo of matter and examined it pixel by pixel.
The halo of gas surrounding the stellar disc accounts for about 70% of the mass of the galaxy – excluding dark matter – but until now has remained something of a mystery. In the past we have only been able to observe the gas by measuring the light from a background object, such as a quasar, that’s absorbed by the gas.
However a new study has observed the circumgalactic medium of a star-bursting galaxy 270 million light years away, using new deep imaging techniques that were able to detect the cloud of gas glowing outside of the galaxy 100,000 light years into space, as far as they were able to look.
To envisage the vastness of that cloud of gas, consider that the galaxy’s starlight – what we would typically view as the disc – extends just 7,800 light years from its centre. The current study observed the physical connection of hydrogen and oxygen from the centre of the galaxy far into space and showed that the physical conditions of the gas changed.
The study adds another piece to the puzzle that’s one of the big questions in astronomy and galaxy evolution – how do they evolve? How do they get their gas? How do they process that gas? And where does it go?
