Planet formation with envelope enrichment: new insights on planetary diversity

Venturini, Julia; Alibert, Yann; Benz, W.

doi:10.1051/0004-6361/201628828

Cited by 128 publications

(162 citation statements)

References 51 publications

(113 reference statements)

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“…First works have recently started to study the compositional aspect (Venturini et al 2016;Lozovsky et al 2017), but they do not yet address the consequences for the luminosity. Because of this, it is currently also not clear if, for the core-mass effect to work efficiently, a high total heavy element content today (in the envelope and/or core) is sufficient as implicitly assumed in the argument above.…”

Section: Uncertainties Related To the Core-mass Effectmentioning

confidence: 99%

“…This would then naturally also reduce its impact on L pf . This should be quantified with future work treating self-consistently the thermodynamics and compositional evolution during formation (e.g., Venturini et al 2016). …”

Section: Post-formation Luminosities L Pfmentioning

confidence: 99%

“…It is clear the future work will have to investigate this in a self-consistent fashion (see Venturini et al 2016;Lozovsky et al 2017, for works that do this for the composition of protoplanets without addressing the luminosity and the solid accretion during gas runaway, though.). First, we assess whether much less potential energy is liberated as L pla,mix by planetesimals that mix throughout the envelope instead of sinking, i.e., whether we are greatly overestimating the heating by impacting planetesimals L pla that in the sinking approximation we use in the syntheses is given approximately by…”

Section: Appendix C: Considerations On the Efficiency Of The Core-masmentioning

confidence: 99%

“…A more definitive answer will however require a fully self-consistent treatment of the problem which is not trivial (non-spherical symmetry of the impacts and thus mass deposition, modification of the EOS, local variation of the opacity, transport processes under the influence of compositional gradients, etc). However, such studies are important given the significant implications for the formation and evolution itself (e.g., Venturini et al 2016;Vazan et al 2016;Lozovsky et al 2017) as well as for the detectability via direct imaging.…”

Section: C7 Summarymentioning

confidence: 99%

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Characterization of exoplanets from their formation

Mordasini

Marleau

Mollière

2017

A&A

116

142

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Context. This paper continues a series in which we predict the main observable characteristics of exoplanets based on their formation. In Paper I we described our global planet formation and evolution model that is based on the core accretion paradigm. In Paper II we studied the planetary mass-radius relationship with population syntheses. Aims. In this paper we present an extensive study of the statistics of planetary luminosities during both formation and evolution. Our results can be compared with individual directly imaged extrasolar (proto)planets and with statistical results from surveys. Methods. We calculated three populations of synthetic planets assuming different efficiencies of the accretional heating by gas and planetesimals during formation. We describe the temporal evolution of the planetary mass-luminosity relation. We investigate the relative importance of the shock and internal luminosity during formation, and predict a statistical version of the post-formation mass vs. entropy "tuning fork" diagram. Because the calculations now include deuterium burning we also update the planetary mass-radius relationship in time.Results. We find significant overlap between the high post-formation luminosities of planets forming with hot and cold gas accretion because of the core-mass effect. Variations in the individual formation histories of planets can still lead to a factor 5 to 20 spread in the post-formation luminosity at a given mass. However, if the gas accretional heating and planetesimal accretion rate during the runaway phase is unknown, the post-formation luminosity may exhibit a spread of as much as 2-3 orders of magnitude at a fixed mass. As a key result we predict a flat log-luminosity distribution for giant planets, and a steep increase towards lower luminosities due to the higher occurrence rate of low-mass (M 10-40 M ⊕ ) planets. Future surveys may detect this upturn. Conclusions. Our results indicate that during formation an estimation of the planetary mass may be possible for cold gas accretion if the planetary gas accretion rate can be estimated. If it is unknown whether the planet still accretes gas, the spread in total luminosity (internal+accretional) at a given mass may be as large as two orders of magnitude, therefore inhibiting the mass estimation. Due to the core-mass effect even planets which underwent cold accretion can have large post-formation entropies and luminosities, such that alternative formation scenarios such as gravitational instabilities do not need to be invoked. Once the number of self-luminous exoplanets with known ages and luminosities increases, the resulting luminosity distributions may be compared with our predictions.

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Section: Uncertainties Related To the Core-mass Effectmentioning

confidence: 99%

Section: Post-formation Luminosities L Pfmentioning

confidence: 99%

Section: Appendix C: Considerations On the Efficiency Of The Core-masmentioning

confidence: 99%

Section: C7 Summarymentioning

confidence: 99%

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Characterization of exoplanets from their formation

Mordasini

Marleau

Mollière

2017

A&A

116

142

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“…In Model-1, crossover is reached after 0.94 Myr, when M Z =16 M ⊕ , while for Model-2, crossover time is 1.54 Myr and M Z =7.5 M ⊕ . Crossover time is calculated assuming that all the accreted planetesimals reach the core, while the deposition of heavies into the envelope is expected to decrease the time by a factor of a few (Venturini et al 2016). Figure 1 shows Z(m) versus time for the two models up to crossover time.…”

Section: Jupiter's Primordial Internal Structurementioning

confidence: 99%

The Fuzziness of Giant Planets’ Cores

Helled

Stevenson

2017

ApJL

135

112

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Giant planets are thought to have cores in their deep interiors, and the division into a heavy-element core and hydrogen-helium envelope is applied in both formation and structure models. We show that the primordial internal structure depends on the planetary growth rate, in particular, the ratio of heavy elements accretion to gas accretion. For a wide range of likely conditions, this ratio is in one-to-one correspondence with the resulting post-accretion profile of heavy elements within the planet. This flux ratio depends sensitively on the assumed solid-surface density in the surrounding nebula. We suggest that giant planets' cores might not be distinct from the envelope and includes some hydrogen and helium, and the deep interior can have a gradual heavy-element structure. Accordingly, Jupiter's core may not be well defined. Accurate measurements of Jupiter's gravitational field by Juno could put constraints on Jupiter's core mass. However, as we suggest here, the definition of Jupiter's core is complex, and the core's physical properties (mass, density) depend on the actual definition of the core and on the planet's growth history.

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Comparing Jupiter interior structure models to Juno gravity measurements and the role of a dilute core

Wahl

Hubbard

Militzer

et al. 2017

Geophysical Research Letters

360

361

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The Juno spacecraft has measured Jupiter's low‐order, even gravitational moments, J2–J8, to an unprecedented precision, providing important constraints on the density profile and core mass of the planet. Here we report on a selection of interior models based on ab initio computer simulations of hydrogen‐helium mixtures. We demonstrate that a dilute core, expanded to a significant fraction of the planet's radius, is helpful in reconciling the calculated Jn with Juno's observations. Although model predictions are strongly affected by the chosen equation of state, the prediction of an enrichment of Z in the deep, metallic envelope over that in the shallow, molecular envelope holds. We estimate Jupiter's core to contain a 7–25 Earth mass of heavy elements. We discuss the current difficulties in reconciling measured Jn with the equations of state and with theory for formation and evolution of the planet.

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Planet formation with envelope enrichment: new insights on planetary diversity

Cited by 128 publications

References 51 publications

Characterization of exoplanets from their formation

Characterization of exoplanets from their formation

The Fuzziness of Giant Planets’ Cores

Comparing Jupiter interior structure models to Juno gravity measurements and the role of a dilute core

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