Просмотрел статью внимательнее.
б) концентрация получается на порядки больше чем на Земле (там жизнь в 1000 раз более жизненная?)
Авторы прямо говорят, что полученная оценка концентрации сильно зависит от модели, поэтому ненадежна.
Цитата:
On the other hand, both the retrieved mixing ratios and temperature are strongly dependent on the available cross sections of DMDS and DMS that are obtained for an Earth-like atmosphere at nearly STP conditions, using N2 as a broadener (I. Gordon et al. 2017). Therefore, the derived abundances and temperatures may be impacted by the assumed collisional broadening factors and/or the adopted molecular cross sections, in general.
По поводу возможности, что это вообще не DMDS/DMS, а другое вещество, они говорят следующее:
Цитата:
While DMDS and DMS best explain the current observations, their combined detection significance is ∼3σ, which is at the lower end of the robustness typically required for scientific evidence. The significance can be readily increased to a 4σ–5σ level by a modest amount of additional JWST time, e.g., between one and three additional transits with MIRI, i.e., only ∼8–24 hr. Second, while we have explored 20 prominent molecules in fitting the spectrum, our search may still not be fully exhaustive. Therefore, future studies could investigate other potential molecules that could explain the data.
Т.е. нужно провести больше наблюдений и проверить больше молекул. Не нашел упоминаний о возможной ненадежности модели атмосферы. Разумеется, это не снимает вопрос, как эта модель проверялась.
По поводу возможного абиогенного происхождения этих веществ авторы пишут:
Цитата:
Experimental studies have demonstrated the feasibility of forming several organosulfur compounds abiotically, using ultraviolet irradiation or electric discharges of gaseous mixtures containing H2S and CH4 (e.g., F. Raulin & G. Toupance 1975; C. He et al. 2020; V. Vuitton et al. 2021; N. W. Reed et al. 2024). In particular, some of these studies have demonstrated the production of both DMS (F. Raulin & G. Toupance 1975; N. W. Reed et al. 2024) and DMDS (C. Sagan & B. N. Khare 1971; B. N. Khare et al. 1978) in gas mixtures containing both CH4 and H2S, arguing in favor of their possible abiotic production in reduced planetary atmospheres. However, both DMS and DMDS are highly reactive and have very short lifetimes in the above experiments (e.g., a few minutes) and in the Earth's atmosphere (between a few hours to ∼1 day), due to various photochemical loss mechanisms (e.g., S. Seager et al. 2013b). Thus, the resulting DMS and DMDS mixing ratios in the current terrestrial atmosphere are quite small (typically ≲1 ppb), despite continual resupply by phytoplankton and other marine organisms.
Therefore, sustaining DMS and/or DMDS at over 10–1000 ppm concentrations in a steady state in the atmosphere of K2-18 b would be implausible without a significant biogenic flux. Moreover, the abiotic photochemical production of DMS in the above experiments requires an even greater abundance of H2S as the ultimate source of sulfur—a molecule that we do not detect—and requires relatively low levels of CO2 to curb DMS destruction (N. W. Reed et al. 2024), contrary to the high reported abundance of CO2 on K2-18 b (N. Madhusudhan et al. 2023b).
Т.е. дело не в том, что DMS/DMDS неоткуда взять, а в том, что он быстро разрушится без постоянного притока. К тому же известные механизмы абиогенного синтеза требуют высокого уровня сероводорода, спектральные линии которого не обнаружены.
Однако авторы, разумеется, не исключают существования неизвестных абиогенных механизмов:
Цитата:
Future laboratory experiments and/or theoretical modeling are also needed to fully explore the possible photochemical mechanisms for producing DMS and DMDS in dry, methane-rich, reduced environments, to address potential abiotic sources of these molecules.
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, если им дадут ещё время на "Веббе".
