Ton 618

TON 618

TON 618 is a contender for largest black hole discovered, being 40 billion times the mass of the Sun and 30-40 as wide as our Solar System.

TON 618 is, strictly speaking, a quasar, but the name also refers to the supermassive black hole (more properly TON 618*) that powers it, which is one of the largest ever discovered. 

Taking its name from the Tonantzintla Observatory in Mexico, it was first observed and catalogued by astronomers Braulio Iriarte and Enrique Chavira in 1957.

TON 618 lies some 18.2 billion lightyears from Earth, in the constellation Canes Venatici, and is 40 billion times the mass of our Sun.

When first observed, TON 618 was thought to be a blue star. Then in 1970 a radio survey conducted in Italy detected radio emissions coming from the object, identifying it as a quasar.

A quasar is type of active galactic nucleus (AGN). Quasars are among the most distant objects you can see with an amateur telescope.

An AGN is a region in the centre of a galaxy that emits significant amounts of electromagnetic radiation, which comes from the material falling into the supermassive black hole that lies at the galaxy’s very heart.

It’s thought that, as supermassive black holes steadily ‘eat’ their way through all of the available gas and dust in the region, the material falling into them emits less and less radiation, so that eventually the galactic centre is no longer active.

AGNs can be broken down into numerous sub-classes based on the strength of the radio waves they emit, the relative proportions of visible, IR and UV light, whether or not they emit X-ray radiation and other spectral characteristics.