Diversity of disc viscosities can explain the period ratios of resonant and non-resonant systems of hot super-Earths and mini-Neptunes
Year: 2024
Type: article
Abstract: Migration is a key ingredient in the formation of close-in super-Earth and mini-Neptune systems. The migration rate sets the resonances in which planets can be trapped, where slower migration rates result in wider resonance configurations compared to higher migration rates. We investigate the influence of different migration rates – set by disc viscosity – on the structure of multi-planet systems via N-body simulations, where planets grow via pebble accretion. Planets in low-viscosity environments migrate slower due to partial gap opening compared to planets forming in high-viscosity environments. Consequently, systems formed in low-viscosity environments tend to have planets trapped in wider resonant configurations (typically 4:3, 3:2, and 2:1 configurations). Simulations of high-viscosity discs mostly produce planetary systems in 7:6, 5:4, and 4:3 resonances. After the gas disc dissipates, the damping forces of eccentricity and inclination cease to exist and the systems can undergo instities on timescales of a few tens of millions of years, rearranging their configurations and breaking the resonance chains. We show that low-viscosity discs naturally account for the configurations of resonant chains, such as Trappist-1, TOI-178, and Kepler-223, unlike high-viscosity simulations, which produce chains that are more compact. Following dispersal of the gas disc, about 95% of our low-viscosity resonant chains became unstable, experiencing a phase of giant impacts. Dynamical instabilities in our low-viscosity simulations are more violent than those of high-viscosity simulations due to the effects of leftover external perturbers (P>200 days). About 50% of our final systems end with no planets within 200 days, while all our systems harbour remaining outer planets. We speculate that this process could be qualitatively consistent with the lack of inner planets in a large fraction of the Sun-like stars. Systems produced in low-viscosity simulations alone do not match the overall period ratio distribution of observations, but give a better match to the period distributions of chains, which may suggest that systems of super-Earths and mini-Neptunes form in natal discs with a diversity of viscosities.
Source: Astronomy and Astrophysics
Authors: Bertram Bitsch, Andre Izidoro
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,732
Awards: GUIDING QUESTION: HOW TO ACQUIRE SUSTAIN AND NURTURE LIFE-ESSENTIAL CHEMICAL INGREDIENTS ON THE SURFACE OF ROCKY PLANETS? BUILDING A HABITABLE ENVIRONMENT ON INNER SOLAR SYSTEM ROCKY SURFACES REQUIRES THE LIFE-ESSENTIAL CHEMICAL INGREDIENTS (C N O H S AND P) TO JOURNEY THROUGH A SERIES OF ASTRONOMICAL PLANETARY GEOLOGICAL AND GEOCHEMICAL PROCESSES DURING PLANET FORMATION AND EARLY PLANETARY EVOLUTION. HOWEVER IN MOST STUDIES ONLY ONE OR FEW OF THESE STEPS ARE INVESTIGATED IN ISOLATION AS CONDITIONS OF HABITABILITY AND THE CONSEQUENCES OF MULTIPLE PATHWAYS THAT MAY BE FEASIBLE ARE NOT RIGOROUSLY EXPLORED. SIMILARLY MOST STUDIES TRACKING THE IMPACT OF PREBIOTIC PROCESSES CONSIDERED THE ORIGIN OF WATER ALONE AND COMPREHENSIVE STUDIES ON A COMBINATION OF LIFE-ESSENTIAL ELEMENTS ARE LACKING. IN ORDER TO EVALUATE THE PATHWAYS THAT MAY LEAD TO EARLY HABITABLE CONDITIONS IN MULTIPLE PLANETARY SURFACES BUT SUSTENANCE ONLY IN A SUBSET AN INTERDISCIPLINARY APPROACH TO STUDY THE EARLY CYCLES OF ALL KEY INGREDIENTS ARE NECESSARY. THIS CAN 8 NAI NODE PROPOSAL AIMS TO CONSTRAIN THE PATHWAYS THAT LEAD TO THE ACQUISITION SUSTENANCE AND NURTURING OF THE LIFE-ESSENTIAL CHEMICAL ELEMENTS AT THE SURFACE AND NEAR-SURFACE ENVIRONMENTS OF ROCKY DIFFERENTIATED PLANETARY BODIES LEADING TO HABITABILITY AND POTENTIALLY DRIVING THE FORMATION OF PREBIOTICALLY-RELEVANT ORGANIC MOLECULE PRECURSORS WITHIN THE FIRST BILLION YEARS OF A PLANET S EVOLUTION. OUR TEAM MEMBERS BRING EXTENSIVE EXPERTISE IN ASTROPHYSICS GEOLOGY GEOCHEMISTRY GEOPHYSICS FLUID AND ATMOSPHERIC DYNAMICS CLIMATE SCIENCE AND ORGANIC CHEMISTRY; AN OVERARCHING GOAL IS TO TRACE THE LIFE-ESSENTIAL ELEMENTS FROM PROTOPLANETARY DISKS TO EARLY PREBIOTIC MOLECULES ON THE SURFACES OF ROCKY PLANETS WITH A PARTICULAR EMPHASIS ON THE FEEDBACKS AMONG INTERIOR SURFACE AND ATMOSPHERIC PROCESSES. WE WILL USE OBSERVATIONS FROM OUR OWN SOLAR SYSTEM IN TERMS OF COMPARATIVE PLANETOLOGY BUT WILL ALSO CONSTRUCT POSSIBLE PATHWAYS THAT MAY LEAD TO THERMO-CHEMICAL HABITABILITY WHICH CAN BE UTILIZED FOR EXPLORATION OF OTHER SOLAR SYSTEMS IN SEARCH FOR LIFE. THE PROPOSED RESEARCH COMPLEMENTS THE ACTIVITIES OF THE CAN 7 TEAMS BECAUSE NONE OF THE CURRENT TEAMS ARE INVESTIGATING THE CYCLES OF THE KEY INGREDIENTS DURING DIFFERENTIATION AND EARLY TECTONO-MAGMATIC AND GEOCHEMICAL EVOLUTION OF ROCKY PLANETS. OUR PROPOSAL WILL BRING IN THE UNIQUE INTERDISCIPLINARY PERSPECTIVE OF CYCLES OF KEY INGREDIENTS OF LIFE THROUGH DEEP TIME FROM GEOLOGIC PLANETARY GEOPHYSICAL AND GEOCHEMICAL PERSPECTIVES. GIVEN THE INTERDEPENDENT NATURE OF THE PROPOSED ACTIVITIES AMONG SEEMINGLY DISPARATE FIELDS OF RESEARCH THE SCOPE OF THIS PROPOSAL CAN ONLY BE SUPPORTED THROUGH AN INSTITUTE WITHOUT WALLS . RELEVANCE TO THE GOALS OF THE ASTROBIOLOGY PROGRAM: THE PROPOSED INVESTIGATION IS RELEVANT FOR SEVERAL OF THE GOALS OF THE ASTROBIOLOGY PROGRAM AS OUTLINED IN THE 2015 STRATEGY INCLUDING THE CENTRAL THEMES OF CONSTRUCTING HABITABLE WORLDS AND IDENTIFYING EXPLORING AND CHARACTERIZING ENVIRONMENTS FOR HABITABILITY AND BIOSIGNATURES . OUR PROPOSAL WILL DIRECTLY ADDRESS QUESTIONS SUCH AS HOW DOES THE STORY OF EARTH IN PARTICULAR IT S PAST INFORM US ABOUT HOW THE CLIMATES ATMOSPHERIC COMPOSITIONS INTERIORS AND BIOSPHERES OF PLANETS CAN CO-EVOLVE? BECAUSE OUR TEAM WILL STUDY THE INTERACTIONS OF INTERIOR ATMOSPHERE AND CLIMATE IN THE FIRST BILLION YEARS OF A ROCKY PLANETS EVOLUTION KEEPING IN MIND THE HISTORY OF THE EARTH AS AN ANALOG. OUR PROPOSAL WILL ALSO DIRECTLY ADDRESS QUESTIONS SUCH AS WHAT ARE THE FUNDAMENTAL INGREDIENTS AND PROCESSES THAT DEFINE A HABITABLE ENVIRONMENT? BECAUSE WE WILL TRACK THE FATE OF THE LIFE-ESSENTIAL ELEMENTS THROUGH THE FUNDAMENTAL PROCESSES OF PLANET FORMATION AND EARLY GEOLOGIC AND BIOGEOCHEMICAL EVOLUTION WITH THE GOAL OF OUTLINING POSSIBLE PATHS THAT ARE OR ARE NOT FAVORABLE IN FINALLY HARBORING THE COHNSP SPECIES AT THE PLANETARY SURFACES., G8457483576
OpenAlex ID: W4404654921