Molecular oxygen discovered for the first time outside the Milky Way

Molecular oxygen discovered for the first time outside the Milky Way
Molecular oxygen discovered for the first time outside the Milky Way

In the biosphere, of which we are a part, oxygen is the most abundant chemical element (if we count by mass). The Earth's crust is made up of almost half of oxygen. There is a lot of it in other corners of the cosmos: in the Universe, oxygen is the third most abundant element, which is second only to hydrogen (about 70 times in mass) and helium (23 times).

Unsurprisingly, astronomers have long expected there to be enough molecular oxygen in interstellar space - the kind we breathe. However, so far all attempts to detect it somewhere outside our Galaxy have yielded no results. The first such observation is reported in a new article published in The Astrophysical Journal.

Junzhi Wang and his colleagues from the Shanghai Astronomical Observatory examined the distant galaxy Markarian 231. It is located in the constellation Ursa Major, more than 580 million light years away, and is considered the closest galaxy with a quasar. A supermassive binary black hole in its active center is absorbing matter so rapidly that the surrounding accretion disk begins to emit bright and narrowly directed fluxes of radiation.

Using radio telescopes NOEMA and IRAM 30m, scientists have discovered in the spectrum of the galaxy, at a characteristic wavelength of 2.52 millimeters, traces of molecular oxygen - for the first time anywhere outside the Milky Way. It is assumed that most of the oxygen in the universe freezes in the form of ice (atomic and water) on the dust particles of interstellar matter. However, in such an active region as the center of Markarian 231, there is a violent star formation (it occurs about a hundred times more intense than in the Milky Way), under the radiation of young stars, atomic oxygen is released and forms molecules.

Previously, molecular oxygen could only be seen in the Orion Nebula (about 1300 light years away) and the Ophiuchus Rho Cloud (460 light years) - within our own Galaxy. However, in Markarian 231 it turned out to be much more than in these clusters: by two orders of magnitude when compared with the Orion Nebula.

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