Article written by: Simon Jeffery
September 2018 will see over 50 astronomers from around the world gather at the Armagh Observatory and Planetarium to discuss the latest news about hydrogen-deficient stars. These stars have lost nearly all the hydrogen from which they were made, to leave only nuclear ash. Astronomers want to learn how these rare and short-lived remnants formed, and what drives their spectacular changes in brightness.
Most of the lights we see in the night sky are stars … objects like the Sun which generate their own light and shine by themselves. Stars come in all sorts, from ten thousand times fainter to a million times brighter than our Sun. Some shine for tens of billions of years, and some burn themselves out in a few thousands. But all are made of the same stuff that was made in the Big Bang: nine atoms of hydrogen to one atom of helium, the two simplest atoms in the Universe.
Therefore, it is very peculiar when we find a star that contains NO hydrogen … even on its surface. And very rare. Only 2 stars out of roughly 5000 visible to the naked eye are “hydrogen-deficient”, or H-def ...