First detected oxygen molecule in another galaxy

Astronomers detected a sign that a large number of oxygen molecules exist in the Markarian galaxy 231, 560 million light-years from Earth.

Oxygen is the third most abundant element in the universe, after hydrogen and helium. So astronomers once thought that the oxygen molecule, or O ₂ , is abundant in the interstellar space. However, after many searches, they have not found this molecule anywhere else in the Milky Way.

Markarian 231 image of the Hubble space telescope recorded.(Photo: NASA).

Junzhi Wang, an astronomer at the Shanghai Astronomical Observatory, and his colleagues first detected signs of an oxygen molecule in the Markarian 231 galaxy , Science News reported on February 18. Markarian 231 is located 560 million light-years from Earth, in the constellation Ursa Major (Dai Hung) is the nearest galaxy containing quasars, an object consisting of gas flows around a supermassive black hole and is so hot that it emits strong light.

Using radio telescopes in Spain and France, the team observed radiation at a wavelength of 2.52mm, an indication of the presence of O ₂ . This is the third time astronomers have discovered oxygen molecules outside the solar system, the numbers also seem to be particularly high. Previously, they had observed O ₂ in two nebulae in the Milky Way, Orion and Rho Ophiuchi.

Scientists believe that the failure to detect O ₂ in interstellar space is due to oxygen atoms and water molecules being frozen on cosmic dust particles. With the Orion and Rho Ophiuchi nebulae, vibrations emanating from new stars may have separated the frozen water from the dust, releasing oxygen atoms, helping them to bond together and form molecules.

In the Orion Nebula, oxygen molecules are rare. The number of hydrogen molecules is one million times more than oxygen molecules. Hydrogen is also abundant in the Markarian 231. However, oxygen molecules extend to the edge of the galaxy disc in quantities more than 100 times in the Orion Nebula.

This number is huge, according to Gary Melnick, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics."There is no clear explanation for how much oxygen molecules appear , " he said.

To confirm that the radiation the team observed was actually coming from O ₂ , they needed to find the second wavelength emitted from the molecule. This is not simply because some other molecules also emit radiation at those wavelengths.

In the case of the Markarian 231 galaxy, the team tested that the molecules produced the same wavelength as the one they observed. As a result, apart from O ₂ , none of these molecules have ever been recorded to appear in outer space . "It could be said to be an exclusion method , " said Paul Goldsmith, a member of the research team and an astronomer at the Jet Propulsion Laboratory.

One hypothesis that could explain the large amount of O ₂ appearing in Markarian 231 is that this galaxy undergoes more intense oxygen generation than the Orion Nebula. Markarian 231 is a very active star factory. It creates new stars 100 times faster than the Milky Way galaxy, and spits out 700 times more gas than the Sun.

High-speed gasses from the galactic center can strike the gas in the galaxy's disk, separating frozen water from dust particles, helping oxygen molecules to form. In turn, O ₂ also helps the galaxy continue to be active. The radiation this molecule emits helps cool the gas, speeding up the process of creating new stars.