Detection of the closest Jovian exoplanet in the Epsilon Indi triple system
"We confirm the trend in the radial velocity data for Epsilon Indi A suggesting a long-period planetary companion and find ... Epsilon Indi Ab as a cold Jupiter with a minimum mass of 2.71+2.19−0.44 MJup on a nearly circular orbit with a semi-major axis of 12.82+4.18−0.71 au and an orbital period of 52.62+27.70−4.12 yr... Thus the Epsilon Indi system comprises of at least Epsilon Indi A, Ab as well as a long period brown dwarf binary Ba and Bb; so it provides a benchmark case for our understanding of the formation of gas giants and brown dwarfs."Gaian bottlenecks and planetary habitability maintained by evolving model biospheres: The ExoGaia model
"We seed multiple model planets with life while their atmospheres are still forming and find that the microbial biospheres are, under suitable conditions, generally able to prevent the host planets from reaching inhospitable temperatures, as would happen on a lifeless planet. We find that the underlying geochemistry plays a strong role in determining long-term habitability prospects of a planet. We find five distinct classes of model planets, including clear examples of 'Gaian bottlenecks' - a phenomenon whereby life either rapidly goes extinct leaving an inhospitable planet, or survives indefinitely maintaining planetary habitability."
This paper uses a highly simplified ("toy") model to look at qualitative behavior of the system, rather than try to make real-world predictions. The five classes are:
Extreme - Planets that never reach habitable temperatures
Doomed - Planets that reach habitable temperatures but are unable to support life.
Critical - Planets that have a higher colonisation success than long-term habitability success.
Bottleneck - Planets that if successfully colonised enjoy long-term habitability.
Abiding - Planets that are always successfully colonised and always have long-term habitability.
Note the ABCDE mnemonic, and that there are cases where planets achieved a biosphere at some point only to have it die out over time.
A key feature that distinguishes the classes (within the context of the model) seems to be the availability of robust geochemical feedback loops, pointing to plate tectonics as a potentially necessary condition for long-term habitability.