SFRPG

Astrometric Constraints on the Masses of Long-Period Gas Giant Planets in the TRAPPIST-1 Planetary System

"...no planet more massive than ∼4.6MJup orbits with a 1 yr period, and no planet more massive than ∼1.6MJup orbits with a 5 yr period."

Color difference makes a difference: four planet candidates around tau Ceti

" We apply this noise model to various radial velocity data sets for tau Ceti, and find four periodic signals at 20.0, 49.3, 160 and 642 d which we interpret as planets."

Tidal Locking of Habitable Exoplanets

"Lower mass stellar hosts will induce stronger tidal effects on potentially habitable planets, and tidal locking is possible for most planets in the habitable zones of GKM dwarf stars."

Temporal evolution of the high-energy irradiation and water content of TRAPPIST-1 exoplanets

"Based on the current knowledge of the stellar irradiation, we investigated the likely history of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape. However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped once they entered the habitable zone."

Habitable Climate Scenarios for Proxima Centauri b With a Dynamic Ocean

"We find that an ocean-covered Proxima b could have a much broader area of surface liquid water but at much colder temperatures than previously suggested, due to ocean heat transport and depression of the freezing point by salinity."

Lecture notes on the formation and early evolution of planetary systems

"These notes provide an introduction to the theory of the formation and early evolution of planetary systems. Topics covered include the structure, evolution and dispersal of protoplanetary disks; the formation of planetesimals, terrestrial and gas giant planets; and orbital evolution due to gas disk migration, planetesimal scattering, planet-planet interactions, and tides."

Challenges in Planet Formation

"Here we review our state of understanding of five fundamental bottlenecks in planet formation. These are: 1) the structure and evolution of protoplanetary disks; 2) the growth of the first planetesimals; 3) orbital migration driven by interactions between proto-planets and gaseous disk; 4) the origin of the Solar System's orbital architecture; and 5) the relationship between observed super-Earths and our own terrestrial planets."

How alien can alien worlds be?

"Our results show that if rocky planets orbit these stars they might have significantly different compositions between themselves and different from that of our Earth."

Is Life Most Likely Around Sun-like Stars?

"We conclude that planets orbiting most M-dwarfs are not likely to host life, and that the highest probability of complex biospheres is for planets around K- and G-type stars."

Habitability of exoplanet waterworlds

"We model the evolution of ocean temperature and chemistry for rocky exoplanets with 10-1000× Earth's H2O but without H2, taking into account C partitioning, high-pressure ice phases, and atmosphere-lithosphere exchange. Within our model, for Sunlike stars, we find that: (1) habitability is strongly affected by ocean chemistry; (2) possible ocean pH spans a wide range; (3) exsolution-driven climate instabilities are possible; (4) surprisingly, many waterworlds stay habitable for >1 Gyr, and (contrary to previous claims) this longevity does not necessarily involve geochemical cycling."

How Special Is the Solar System?

"... I have not identified any physical parameters which convincingly demonstrate that life on Earth, or even intelligent life, is unique, either in the universe as a whole, or even in the Milky Way galaxy."

Long-Term Stability of Tightly Packed Multi-Planet Systems in Prograde, Coplanar, Circumstellar Orbits within the α Centauri AB System

"A total of up to nine [Earth-mass] planets on nested prograde orbits can survive for the current age of the system within the empirical HZs of the two stars, with five of these orbiting α Centauri B and four orbiting α Centauri A."

Dependence of the onset of the runaway greenhouse effect on the latitudinal surface water distribution of Earth-like planets

"We found that the runaway greenhouse threshold varies continuously with the surface water distribution from about 130% (an aqua planet) to 180% (the extreme case of a land planet) of the present insolation at Earth's orbit."

Formation of terrestrial planets in eccentric and inclined giant planet systems

"While coplanar giant systems harbour several terrestrial planets, generally as massive as the Earth and mainly on low eccentric and low inclined orbits, terrestrial planets formed in systems with mutually inclined giant planets are usually fewer, less massive (<0.5 M_{\Earth}) and with larger eccentricities and inclinations. This work shows that terrestrial planets can form on stable inclined orbits through the classical accretion theory, even in coplanar giant planet systems emerging from the disc phase."

On the bio-habitability of M-dwarf planets

"Instead of the traditional definition of the habitable zone, we define the bio-habitable zone, where liquid water and complex organic molecules can survive on at least part of the planetary surface.... Our results suggest that planets orbiting M-type stars may have life-supporting temperatures, at least on part of their surface, for a wide range of atmospheric properties."

The nature of the TRAPPIST-1 exoplanets

"We find that TRAPPIST-1, c and e likely have largely rocky interiors, while planets b, d, f, g, and h require envelopes of volatiles in the form of thick atmospheres, oceans, or ice, in most cases with water mass fractions less than 5%."