The First Discovery Of Oxygen Outside The Milky Way Galaxy

O2 has been detected around the core of the Markarian 231 galaxy. So far it has only been found in two locations in our galaxy and in the solar system.

Discovery of oxygen outside the Milky Way.
Discovery of oxygen outside the Milky Way.

Astronomers find another galaxy where there is oxygen to breathe.

🔹 Astronomers were able to identify molecular oxygen in another galaxy called Markarian 231, located 581 million light years from us.

Every time you drink a glass of H2O you are ingesting a liquid that is mostly about 13.4 billion years old, since the hydrogen atoms in the water formed only hundreds of thousands of years after the Big Bang. 

The oxygen atoms that complete the recipe for water are more recent: they formed at least 100 million years after the Big Bang, since they were "forged" in the bowels of the stars through nuclear fusion reactions, and the stars were not born until then.

In fact, thanks to the tireless work of stars, oxygen is the third most abundant chemical element in the universe. That is why molecular oxygen (O2) would be one of the easiest molecules to find in the molecular clouds. 

These are regions of the interstellar space in which matter is most concentrated, so it looks like a cloud and allows molecules to form (while in other regions of the interstellar space there are no molecules but ionised gas). 

But until now only oxygen has been found in the solar system and in two points of the galaxy: specifically, in the clouds of the Orion Nebula and the Rho Ophiuchi. 

Why this happens is unknown, but it is believed that it is not found elsewhere because O2 binds to the dust made by stars and escapes detection by telescopes.

The first detection outside the Milky Way

This week, a group of astronomers from the Chinese Academy of Sciences (CSA) announced the discovery of oxygen outside the Milky Way for the first time. The scientists, led by Junzhi Wang, have detected molecular oxygen in the Markarian 231 or UGC 08058 galaxy, located about 561 million light years from Earth. 

🔹 Their conclusions have been published in "The Astrophysical Journal".

"Markarian 231" is a galaxy discovered in 1969 and is characterized by the closest quasar to the solar system. Quasars are extremely powerful sources of radiation that form when a supermassive black hole in the centre of a galaxy begins to swallow up the gas and stars that come too close to its gravitational "jaws". 

The result is, among other things, a monstrous release of energy through cosmic jets that function as gigantic particle accelerators.

The oxygen "factory" of "Markarian 231"

Wang's team suspected that the radiation released by the heart of "Markarian 231" may trigger the release of oxygen into its environment. The idea is that this oxygen would be in the form of water molecules in molecular clouds located around the quasar. 

🔹 But when the quasar's powerful radiation hits the water, it would break up and allow oxygen to be detected from the Earth.

For this reason, Wang's team set out to investigate the Markarian 231 galaxy with the 30-metre radio telescope at the Institute of Millimetric Radio Astronomy in Granada, Spain. After four days of observations, in which they tracked the galaxy at various wavelengths, they effectively detected the molecular oxygen footprint.

In particular, oxygen molecules were located at a distance of more than 32,000 light years from the convulsed centre of "Markarian 231", as Michelle Starr wrote in "".

The birth of new stars

The ratio of oxygen to molecular hydrogen is 100 times higher in "Markarian 231" than in the Orion nebula. There, by the way, the molecular clouds release oxygen after being bombarded by the radiation from young stars, and not by a quasar, as in the distant galaxy.

Since "Markarian 231" is a very active galaxy capable of producing enormous quantities of stars, these findings have interesting implications. If these conclusions are confirmed, the work of Wang and colleagues would be very important for understanding the role of molecular oxygen in galaxies and in the formation of new stars. 

As the authors have suggested, "O2 could be an important for the molecular clouds affected by the flows of the active nuclei of galaxies - quasars".