Scientists conducted a series of studies to determine whether the presence of ozone on the planet could be detected by the presence of molecular oxygen. To do this, they modeled how nitrogen oxide, methane, and stellar activity affect the ratio of these substances.
Ozone and oxygen
Although oxygen is an important biomarker, i.e., a substance that indicates the possible presence of life on a planet, there is actually another molecule whose presence indicates this even better: ozone. It forms a protective shield above the Earth, absorbing the most harmful part of ultraviolet radiation.
A series of articles in Astronomy & Astrophysics magazine is devoted to its possible discovery. The fact is that ozone is usually much more difficult to detect using spectroscopy than oxygen because there is less of it and it is less stable.
In general, ozone is also oxygen, only its molecule consists of three atoms instead of two. Indeed, these two molecules easily transform into each other. This is precisely the basis for the assumption that the authors of the study tested in their series of articles: we can determine the amount of ozone on the planet by measuring the amount of oxygen, and vice versa.
The only problem is that their ratio is nonlinear, and we do not know the nature of this curve. It was the one that scientists were trying to identify. In the first article, they identified general patterns, and in the second, they examined how the presence of nitrogen oxide N2O affects this ratio. And now it is methane’s turn.
Methane, oxygen, and stars
The research was conducted using computer modeling. They have succeeded in creating a convincing model of the planet’s atmosphere that works well regardless of the spectral class of the star around which the planet orbits.
The general conclusion drawn by scientists is as follows: fluctuations in methane levels affect the ratio of oxygen to ozone. However, variations in the star’s luminosity have an even greater influence on it. Moreover, if a planet with a high methane content orbits a hot star, the latter turns into water, causing a greenhouse effect, which further alters the methane content.
There are many scenarios where high levels of CH4 can increase O3 levels in the atmosphere, while high levels of N2O simultaneously deplete this O3. This shows that we need to take into account variations in both types in order to use O3 measurements to study the O2 content in the atmosphere.
According to phys.org
