The new generation planetary population synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems

Six transiting planets and a chain of Laplace resonances in TOI-178

10.5194/epsc2021-811 ◽

2021 ◽

Author(s):

Adrien Leleu

Keyword(s):

Planet Formation ◽

Planetary Systems ◽

Single System ◽

Transiting Planets ◽

Orbital Configuration ◽

Resonant Systems ◽

Formation And Evolution ◽

A Chain ◽

Formation Phase

Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. As unveiled by TESS, CHEOPS, ESPRESSO, NGTS and SPECULOOS, TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, all planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet. TOI-178 have hence several characteristics that were not previously observed in a single system, making it a key system for the study of processes of formation and evolution of planetary systems. We will review what we know of TOI-178, and what we expect from futur observations.

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Diverse outcomes of planet formation and composition around low-mass stars and brown dwarfs

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3007 ◽

2019 ◽

Cited By ~ 5

Author(s):

Y Miguel ◽

A Cridland ◽

C W Ormel ◽

J J Fortney ◽

S Ida

Keyword(s):

Planet Formation ◽

Planetary Systems ◽

Brown Dwarfs ◽

Population Synthesis ◽

Optimal Conditions ◽

Low Mass Stars ◽

Water Fraction ◽

Low Mass ◽

M Stars ◽

Mass Form

Abstract The detection of Earth-size exoplanets around low-mass stars –in stars such as Proxima Centauri and TRAPPIST-1– provide an exceptional chance to improve our understanding of the formation of planets around M stars and brown dwarfs. We explore the formation of such planets with a population synthesis code based on a planetesimal-driven model previously used to study the formation of the Jovian satellites. Because the discs have low mass and the stars are cool, the formation is an inefficient process that happens at short periods, generating compact planetary systems. Planets can be trapped in resonances and we follow the evolution of the planets after the gas has dissipated and they undergo orbit crossings and possible mergers. We find that formation of planets above Mars mass and in the planetesimal accretion scenario, is only possible around stars with masses M⋆ ≥ 0.07Msun and discs of Mdisc ≥ 10−2 Msun. We find that planets above Earth-mass form around stars with masses larger than 0.15 Msun, while planets larger than 5 M⊕ do not form in our model, even not under the most optimal conditions (massive disc), showing that planets such as GJ 3512b form with another, more efficient mechanism. Our results show that the majority of planets form with a significant water fraction; that most of our synthetic planetary systems have 1, 2 or 3 planets, but planets with 4,5,6 and 7 planets are also common, confirming that compact planetary systems with many planets should be a relatively common outcome of planet formation around small stars.

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The New Generation Planetary Population Synthesis (NGPPS). IV. Planetary systems around low-mass stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/202140390 ◽

2021 ◽

Author(s):

R. Burn ◽

M. Schlecker ◽

C. Mordasini ◽

A. Emsenhuber ◽

Y. Alibert ◽

...

Keyword(s):

Planetary Systems ◽

Population Synthesis ◽

Low Mass Stars ◽

Low Mass ◽

New Generation

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Global models of planet formation and evolution

International Journal of Astrobiology ◽

10.1017/s1473550414000263 ◽

2014 ◽

Vol 14 (2) ◽

pp. 201-232 ◽

Cited By ~ 76

Author(s):

C. Mordasini ◽

P. Mollière ◽

K.-M. Dittkrist ◽

S. Jin ◽

Y. Alibert

Keyword(s):

Extrasolar Planets ◽

Planet Formation ◽

Synthesis Method ◽

Mass Function ◽

Strong Increase ◽

Solid Core ◽

Population Synthesis ◽

Global Models ◽

Astrophysical Objects ◽

Formation And Evolution

AbstractDespite the strong increase in observational data on extrasolar planets, the processes that led to the formation of these planets are still not well understood. However, thanks to the high number of extrasolar planets that have been discovered, it is now possible to look at the planets as a population that puts statistical constraints on theoretical formation models. A method that uses these constraints is planetary population synthesis where synthetic planetary populations are generated and compared to the actual population. The key element of the population synthesis method is a global model of planet formation and evolution. These models directly predict observable planetary properties based on properties of the natal protoplanetary disc, linking two important classes of astrophysical objects. To do so, global models build on the simplified results of many specialized models that address one specific physical mechanism. We thoroughly review the physics of the sub-models included in global formation models. The sub-models can be classified as models describing the protoplanetary disc (of gas and solids), those that describe one (proto)planet (its solid core, gaseous envelope and atmosphere), and finally those that describe the interactions (orbital migration and N-body interaction). We compare the approaches taken in different global models, discuss the links between specialized and global models, and identify physical processes that require improved descriptions in future work. We then shortly address important results of planetary population synthesis like the planetary mass function or the mass–radius relationship. With these statistical results, the global effects of physical mechanisms occurring during planet formation and evolution become apparent, and specialized models describing them can be put to the observational test. Owing to their nature as meta models, global models depend on the results of specialized models, and therefore on the development of the field of planet formation theory as a whole. Because there are important uncertainties in this theory, it is likely that the global models will in future undergo significant modifications. Despite these limitations, global models can already now yield many testable predictions. With future global models addressing the geophysical characteristics of the synthetic planets, it should eventually become possible to make predictions about the habitability of planets based on their formation and evolution.

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The Obliquity of HIP 67522 b: A 17 Myr Old Transiting Hot, Jupiter-sized Planet

The Astrophysical Journal ◽

10.3847/2041-8213/ac3485 ◽

2021 ◽

Vol 922 (1) ◽

pp. L1

Author(s):

Alexis Heitzmann ◽

George Zhou ◽

Samuel N. Quinn ◽

Stephen C. Marsden ◽

Duncan Wright ◽

...

Keyword(s):

Surface Brightness ◽

Planet Formation ◽

Giant Planet ◽

Young Stars ◽

Global Model ◽

High Eccentricity ◽

A Value ◽

Special Place ◽

Migration History ◽

Formation And Evolution

Abstract HIP 67522 b is a 17 Myr old, close-in (P orb = 6.96 days), Jupiter-sized (R = 10 R ⊕) transiting planet orbiting a Sun-like star in the Sco–Cen OB association. We present our measurement of the system’s projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of ∣ λ ∣ = 5.8 − 5.7 + 2.8 ° it is unlikely that this well-aligned system is the result of a high-eccentricity-driven migration history. By being the youngest planet with a known obliquity, HIP 67522 b holds a special place in contributing to our understanding of giant planet formation and evolution. Our analysis shows the feasibility of such measurements for young and very active stars.

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On the role of orbital migration in the early phases of the evolution of planetary systems

10.5194/epsc2020-820 ◽

2020 ◽

Author(s):

Zijia Cui ◽

John Papaloizou ◽

Ewa Szuszkiewicz

Keyword(s):

Planet Formation ◽

Planetary Systems ◽

Leading Edge ◽

Quality Data ◽

Extrasolar Planet ◽

Population Synthesis ◽

Semi Major Axis ◽

Planetary Mass ◽

Gap Opening ◽

Orbital Migration

Past, present and forthcoming space missions (e.g. Kepler/K2, TESS, CHEOPS, JWST, PLATO, ARIEL) and ground-based observational facilities (e.g. VLT, VLTI, ALMA) were, are and will be the sources of the high quality data necessary to unveil the properties of the planetary systems. Thanks to them the recent enormous increase in number of known planets gives a unique opportunity to study the processes responsible for planet formation and evolution in more detail. The observed properties of numerous planets allow for the robust constraints to be put on planet formation models. Both ground and space-based surveys have derived distributions of fundamental planetary properties like the frequency of planets in the mass-distance and radius-distance planes, the planetary mass function, the eccentricity distribution, or the planetary mass-radius relation. Now it is possible to compare the theoretical predictions with the observed properties of the planet population as a whole. The technique used for this comparison is known as the planet population synthesis [1-4]. One of the assumptions in this method is the migration rate of the planets. At the early stages of the evolution, when planets are still embedded in a gaseous disc, the tidal interactions between the disc and planets cause the planetary orbital migration. The orbital migration may play an important role in shaping stable planetary configurations. The outcome of the simulation depends strongly on the way in which the planets migrate. An understanding of this stage of the evolution will provide insight on the most frequently formed architectures, which in turn are relevant for determining the planet habitability. There has been recently an important development in the understanding of the orbital migration of planets which are able to open a partial gap in the protoplanetary disc (e.g. [5], [6], and references therein). It has been shown that such planets migrate differently than it has been assumed till now [7]. This subject is now at the leading edge of the studies of the dynamical interactions that occur in newly formed planetary systems. Here, we are going to present our most recent results on the two super-Earths migrating in a gaseous protoplanetary disc. [1] Mordasini, C., Alibert, Y., Benz, W. (2009), Extrasolar planet population synthesis. I. Method, formation tracks, and mass-distance distribution, A&A, 501, 1139 [2] Mordasini, C., Alibert, Y., Benz, W., Naef, D. (2009), Extrasolar planet population synthesis. II. Statisticalcomparison with observations, A&A, 501, 1139 [3] Alibert, Y., Carron, F., Fortier, A., et al. (2013), Theoretical models of planetary system formation: mass vs. semi-major axis, A&A, 558, A109 [4] Benz, W., Ida, S., Alibert, Y., Lin, D., & Mordasini, C. (2014), Planet Population Synthesis, Protostars and Planets VI, 691 [5] Robert C. M. T., Crida A., Lega E., M&#233;heut H., Morbidelli A. (2018) Toward a new paradigm for Type II migration, A&A, 617, A98 [6] Kanagawa, K. D., Tanaka, H., & Szuszkiewicz, E, (2018), Radial migration of gap-opening planets in protoplanetary disks. I. The case of a single planet ApJ, 861, 140 [7] Duffell, P. C., Haiman, Z., MacFadyen, A. I., D&#8217;Orazio, D. J., Farris, B. D. (2014), The Migration of&#160; Gap-Opening Planets is not Locked to Viscous Disk Evolution , ApJL, 792, L10

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The First Galaxies in the Universe

10.23943/princeton/9780691144917.001.0001 ◽

2013 ◽

Author(s):

Abraham Loeb ◽

Steven R. Furlanetto

Keyword(s):

Galaxy Evolution ◽

Big Bang ◽

First Stars ◽

Distant Galaxies ◽

Formation And Evolution ◽

Early Galaxies ◽

First Galaxies ◽

Large Telescopes ◽

New Generation ◽

The Big Bang

This book provides a comprehensive, self-contained introduction to one of the most exciting frontiers in astrophysics today: the quest to understand how the oldest and most distant galaxies in our universe first formed. Until now, most research on this question has been theoretical, but the next few years will bring about a new generation of large telescopes that promise to supply a flood of data about the infant universe during its first billion years after the big bang. This book bridges the gap between theory and observation. It is an invaluable reference for students and researchers on early galaxies. The book starts from basic physical principles before moving on to more advanced material. Topics include the gravitational growth of structure, the intergalactic medium, the formation and evolution of the first stars and black holes, feedback and galaxy evolution, reionization, 21-cm cosmology, and more.

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Metallicity effect and planet mass function in pebble-based planet formation models

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833347 ◽

2018 ◽

Vol 619 ◽

pp. A174 ◽

Cited By ~ 14

Author(s):

N. Brügger ◽

Y. Alibert ◽

S. Ataiee ◽

W. Benz

Keyword(s):

Internal Structure ◽

Planet Formation ◽

Large Fraction ◽

Mass Function ◽

Planetary Atmosphere ◽

Population Synthesis ◽

Core Accretion ◽

Mass Functions ◽

Synthesis Approach ◽

Gaseous Envelope

Context. One of the main scenarios of planet formation is the core accretion model where a massive core forms first and then accretes a gaseous envelope. This core forms by accreting solids, either planetesimals or pebbles. A key constraint in this model is that the accretion of gas must proceed before the dissipation of the gas disc. Classical planetesimal accretion scenarios predict that the time needed to form a giant planet’s core is much longer than the time needed to dissipate the disc. This difficulty led to the development of another accretion scenario, in which cores grow by accretion of pebbles, which are much smaller and thus more easily accreted, leading to more rapid formation. Aims. The aim of this paper is to compare our updated pebble-based planet formation model with observations, in particular the well-studied metallicity effect. Methods. We adopt the Bitsch et al. (2015a, A&A, 575, A28) disc model and the Bitsch et al. (2015b, A&A, 582, A112) pebble model and use a population synthesis approach to compare the formed planets with observations. Results. We find that keeping the same parameters as in Bitsch et al. (2015b, A&A, 582, A112) leads to no planet growth due to a computation mistake in the pebble flux (2018b). Indeed a large fraction of the heavy elements should be put into pebbles (Zpeb∕Ztot = 0.9) in order to form massive planets using this approach. The resulting mass functions show a huge amount of giants and a lack of Neptune-mass planets, which are abundant according to observations. To overcome this issue we include the computation of the internal structure for the planetary atmosphere in our model. This leads to the formation of Neptune-mass planets but no observable giants. Furthermore, reducing the opacity of the planetary envelope more closely matches observations. Conclusions. We conclude that modelling the internal structure for the planetary atmosphere is necessary to reproduce observations.

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Magnetically induced termination of giant planet formation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833611 ◽

2018 ◽

Vol 619 ◽

pp. A165 ◽

Cited By ~ 7

Author(s):

A. J. Cridland

Keyword(s):

Magnetic Field ◽

Cross Section ◽

Planet Formation ◽

Giant Planet ◽

Effective Cross Section ◽

Cold Start ◽

Population Synthesis ◽

Hot Start ◽

Gas Accretion ◽

Planetary Magnetic Field

Here a physical model for terminating giant planet formation is outlined and compared to other methods of late-stage giant planet formation. As has been pointed out before, gas accreting into a gap and onto the planet will encounter the planetary dynamo-generated magnetic field. The planetary magnetic field produces an effective cross section through which gas is accreted. Gas outside this cross section is recycled into the protoplanetary disk, hence only a fraction of mass that is accreted into the gap remains bound to the planet. This cross section inversely scales with the planetary mass, which naturally leads to stalled planetary growth late in the formation process. We show that this method naturally leads to Jupiter-mass planets and does not invoke any artificial truncation of gas accretion, as has been done in some previous population synthesis models. The mass accretion rate depends on the radius of the growing planet after the gap has opened, and we show that so-called hot-start planets tend to become more massive than cold-start planets. When this result is combined with population synthesis models, it might show observable signatures of cold-start versus hot-start planets in the exoplanet population.

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