Extrasolar planet population synthesis I: Method, formation tracks and mass-distance distribution

By C. Mordasini, Y. Alibert, W. Benz. 2009

435 citations recorded by the source corpus.

With the high number of extrasolar planets discovered by now, it becomes possible to constrain theoretical formation models in a statistical sense. This paper is the first in a series in which we carry out a large number of planet population synthesis calculations. We begin the series with a paper mainly dedicated to the presentation of our approach, but also the discussion of a representative synthetic planetary population of solar like stars. Based as tightly as possible on observational data, we have derived probability distributions for the most important initial conditions for the planetary formation process. We then draw sets of initial conditions from these distributions and obtain the corresponding synthetic planets with our formation model. Although the main purpose of this paper is the description of our methods, we present some key results: We find that the variation of the initial conditions in the limits occurring in nature leads to the formation of planets of large diversity. This formation process is best visualized in planetary formation tracks, where different phases of concurrent growth and migration can be identified. These phases lead to the emergence of sub-populations of planets distinguishable in a mass-semimajor axis diagram. The most important ones are the "failed cores", a vast group of core-dominated low mass planets, the "horizontal branch", a sub-population of Neptune mass planets extending out to 6 AU, and the "main clump", a concentration of giant gaseous giants planets at around 0.3-2 AU.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/df62ac217312faef175dab2e33cfffb280becddd

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Citations in the corpus

Characterization of exoplanets from their formation - II. The planetary mass-radius relationship (2012, methodology): “self-gravity In population synthesis calculations (e.g. Ida & Lin 2004; Mordasini et al. 2009a) one uses distributions of (initial) protoplanetary disk masses in order to reflect the varying initial conditions for planet formation.”
TOWARD CHEMICAL CONSTRAINTS ON HOT JUPITER MIGRATION (2014, methodology): “We adopt the Type II migration rate used by Ida & Lin (2004), though other migration prescriptions are possible(e.g. Mordasini et al. 2009).”
Extrasolar planet population synthesis - IV. Correlations with disk metallicity, mass, and lifetime (2012, methodology): “They indicate (e.g. Mordasini et al. 2009a) that runaway bodies should emerge with a uniform distribution in log(astart), as already adopted by Ida & Lin (2004a).”
Is tidal heating sufficient to explain bloated exoplanets? Consistent calculations accounting for finite initial eccentricity (2010, positive): “1MJ region, and can be explained with a MZ/Mp>∼ 0.10 heavy material enrichment (Baraffe et al. 2008), in good agreement with predictions of the core accretion scenario for planet formation (Baraffe et al. 2006; Mordasini et al. 2009).”
STELLAR ROTATION PERIODS OF THE KEPLER OBJECTS OF INTEREST: A DEARTH OF CLOSE-IN PLANETS AROUND FAST ROTATORS (2013, background): “Detailed theoretical models are needed to understand the evolution of the angular momentum of star-planet systems (e.g. Mordasini et al. 2009).”
RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, background): “An important goal is to generate models that incorporate empirical insights on the properties of circumstellar disks and are able to reproduce key demographic features of the exoplanet population (e.g., Ida & Lin 2004, 2005; Alibert et al. 2005; Mordasini et al. 2009).”
The Disk Substructures at High Angular Resolution Project (DSHARP). I. Motivation, Sample, Calibration, and Overview (2018, background): “…spatial distribution of densities and temperatures; Andrews et al. 2009, 2010; Isella et al. 2009, 2010) and predicts the key characteristics of the exoplanet population (e.g., masses, orbital architectures, atmosphere compositions; Ida & Lin 2004, 2008; Alibert et al. 2005; Mordasini et al. 2009).”
THE GEMINI/NICI PLANET-FINDING CAMPAIGN: THE FREQUENCY OF PLANETS AROUND YOUNG MOVING GROUP STARS (2013, background): “Such widely separated companions pose a challenge for the accepted model of core-accretion formation, which likely formed the closer-in (<10 AU) population of planets detected to date via radial velocity studies (e.g., Mordasini et al. 2009; Janson et al. 2012; Dodson-Robinson et al. 2009).”
THE MASS DEPENDENCE BETWEEN PROTOPLANETARY DISKS AND THEIR STELLAR HOSTS (2013, background): “…invoked as a key factor in accounting for the diverse demographic properties of the exoplanets (e.g., Ida & Lin 2004, 2008; Alibert et al. 2005; Mordasini et al. 2009), and scaling trends between Md and other star/disk properties are speculated to generate some of the basic relations that are…”
PLANETARY POPULATION SYNTHESIS COUPLED WITH ATMOSPHERIC ESCAPE: A STATISTICAL VIEW OF EVAPORATION (2014, background): “These assumptions are more realistic than the assumptions in Mordasini et al. (2009), wherein nonirradiated disks were used with only the thermal criterion and a type I migration rate with a reduction factor of 0.001.”
Estimation of the XUV radiation onto close planets and their evaporation (2011, methodology): “Simulations carried out by, e.g., Mordasini et al. (2009) do not cover planets withaP < 0.1 a.u, and more recent simulations (Benı́tez-Llambay et al., 2011) might justify only the gap observed in the mass-distance diagram atM <∼ 1 MJ and 8 Table 7.”
REVEALING A UNIVERSAL PLANET–METALLICITY CORRELATION FOR PLANETS OF DIFFERENT SIZES AROUND SOLAR-TYPE STARS (2013, positive): “…correlation provides a critical diagnostic for planet formation mechanisms: the correlation for gas-giant planets is consistent with the core accretion scenario for exoplanets that orbit closer than 20 AU around main sequence stars (Ida & Lin 2004; Mordasini et al. 2009; Alibert et al. 2011).”
The HARPS search for Earth-like planets in the habitable zone - I. Very low-mass planets around HD 20794, HD 85512, and HD 192310 (2011, background): “Theoretical works by Mordasini et al. (2009) actually forecasted that the frequency of small Neptunes and super-Earths on short and intermediated orbits would be considerably higher than that of Saturns and Jupiters.”
MIGRATION THEN ASSEMBLY: FORMATION OF NEPTUNE-MASS PLANETS INSIDE 1 AU (2011, background): “This is in contrast to the results of the predominant planet population synthesis models (e.g., Ida & Lin 2008; Mordasini et al. 2009), which predict that this mass range (10–50 M⊕) should be liberally populated with partially accreted giant planet cores (“hot Neptunes”) that have migrated in from…”
The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets (2017, background): “The large number of planets smaller than Neptune discovered by the Kepler mission was unexpected given prevailing theories of planet formation, which were developed to explain the distribution of giant planets (Ida & Lin 2004; Mordasini et al. 2009).”
ALMA SURVEY OF LUPUS PROTOPLANETARY DISKS. I. DUST AND GAS MASSES (2016, background): “…emission are needed to probe the evolution of bulk dust and gas content; these fundamental properties dictate the planet-forming capacity of disks (e.g., Alibert et al. 2005; Mordasini et al. 2009; Bitsch et al. 2015) and thus can help explain the diverse nature of the resulting exoplanet systems.”