On the Possibility of Observing Nitric Oxide on Terrestrial Exoplanets Using the WSO-UV Observatory

It is generally believed that the presence of a N_2-O_2 -dominant atmosphere is an indication of biological and geological activity on terrestrial exoplanets that are in the habitable region. One of indicators of such an atmosphere is the nitric oxide (NO) molecule. It is known from satellite observations of the Earth’s atmosphere that the brightest nitric oxide band in the ultraviolet range is the γ band (203–248 nm). Space telescopes such as the existing HST and the upcoming WSO-UV can observe in this spectral range. The paper presents estimates of the luminosity of various exoplanets in the NO γ band. It has been established that the detection of NO emission in the γ band in the atmospheres of typical terrestrial exoplanets is possible using the spectrographs of the WSO-UV observatory within a reasonable observational time (5 WSO-UV orbits or 120 observation hours).