Related papers: The K Dwarf Advantage for Biosignatures on Directl…
Chemical disequilibrium in planetary atmospheres has been proposed as a generalized method for detecting life on exoplanets through remote spectroscopy. Among solar system planets with substantial atmospheres, the modern Earth has the…
Methane (CH4) is a primarily biogenic greenhouse gas. As such, it represents an essential biosignature to search for life on exoplanets. Atmospheric CH4 abundance on Earth-like inhabited exoplanets is likely controlled by marine biogenic…
With the recent discoveries of terrestrial planets around active M-dwarfs, destruction processes masking the possible presence of life are receiving increased attention in the exoplanet community. We investigate potential biosignatures of…
M dwarfs have long been prime targets in the search for habitable exoplanets, owing to their abundance in the galaxy and the relative ease of detecting Earth-sized worlds within their narrower habitable zones. Yet, these low-mass stars can…
Planets orbiting in the habitable zone (HZ) of M-Dwarf stars are subject to high levels of galactic cosmic rays (GCRs) which produce nitrogen oxides in earthlike atmospheres. We investigate to what extent this NOx may modify biomarker…
The first potential exoplanet biosignature detections are likely to be ambiguous due to the potential for false positives: abiotic planetary processes that produce observables similar to those anticipated from a global biosphere. Here we…
We have obtained near-infrared spectra of three L dwarfs discovered by 2MASS, 1506+13 (L3), 1507-16 (L5), and 0920+35 (L6.5). From the comparison of the H and K band spectra of these L dwarfs, we have found the presence of methane…
We investigate the chemical stability of CO2-dominated atmospheres of desiccated M dwarf terrestrial exoplanets using a 1-dimensional photochemical model. Around Sun-like stars, CO2 photolysis by Far-UV (FUV) radiation is balanced by…
The search for signs of life through the detection of exoplanet atmosphere biosignature gases is gaining momentum. Yet, only a handful of rocky exoplanet atmospheres are suitable for observation with planned next-generation telescopes. To…
Volatile loss from exoplanetary atmospheres and its possible implications for the longevity of habitable surface conditions is a topic of vigorous debate currently. The vast majority of the habitable zone terrestrial-like exoplanets known…
Terrestrial extrasolar planets around low-mass stars are prime targets when searching for atmospheric biosignatures with current and near-future telescopes. The habitable-zone Super-Earth LHS 1140 b could hold a hydrogen-dominated…
In the search for life in the Universe, molecular oxygen (O$_2$) combined with a reducing species, such as methane (CH$_4$), is considered a promising disequilibrium biosignature. In cases where it would be difficult or impossible to detect…
Hazes are common in known planet atmospheres, and geochemical evidence suggests early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic…
Lightning has been suggested to play a role in triggering the occurrence of bio-ready chemical species. Future missions (PLATO, ARIEL, HWO, LIFE) and ground-based ELTs will investigate the atmospheres of potentially habitable exoplanets. We…
O2 and O3 have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary…
Efforts to discover and characterize habitable zone planets have primarily focused on Sun-like stars and M dwarfs. K stars, however, provide an appealing compromise between these two alternatives that has been relatively unexplored.…
Recent discoveries of potentially habitable exoplanets have ignited the prospect of spectroscopic investigations of exoplanet surfaces and atmospheres for signs of life. This chapter provides an overview of potential surface and temporal…
Many past studies have predicted the steady-state production and maintenance of abiotic O$_2$ and O$_3$ in the atmospheres of CO$_2$-rich terrestrial planets orbiting M dwarf stars. However, the time-dependent responses of these planetary…
The near-term search for life beyond the solar system currently focuses on transiting planets orbiting small M dwarfs, and the challenges of detecting signs of life in their atmospheres. However, planets orbiting white dwarfs (WDs) would…
The presence of chlorofluorocarbons (CFCs) in Earth's atmosphere is a direct result of technology. Ozone-depleting CFCs have been banned by most countries, but some CFCs have persistent in elevated concentrations due to their long…