The light and dust of a starburst galaxy

Posted by Thomas Anderson

Visible as a small, sparkling hook in the dark sky, the beautiful object below snapped by NASA's Hubble Space Telescope is known as J082354.96+280621.6, or J082354.96 for short.



This occurs when electrons within a hydrogen atom fall from a higher energy level to a lower one, emitting light as they do so. This emission is interesting because this light leaves its host galaxy only after extensive scattering in the nearby gas - meaning that this light can be used as a pretty direct probe of what a galaxy is made up of.

The study of this Lyman-alpha emission is common in very distant galaxies, but now a study named LARS (Lyman Alpha Reference Sample) is investigating the same effect in galaxies that are closer by.

Astronomers chose fourteen galaxies, including this one, and used spectroscopy and imaging to see what was happening within them. They found that these Lyman-alpha photons can travel much further if a galaxy has less dust - meaning that we can use this emission to infer just how dusty the source galaxy is.