Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2009.06448

Constraining protoplanetary disks with exoplanetary dynamics: Kepler-419 as an example

Mohamad Ali-Dib·Cristobal Petrovich
View original source ↗Read source document ↗Export metadata ↓

Abstract

We investigate the origins of Kepler-419, a peculiar system hosting two nearly coplanar and highly eccentric gas giants with apsidal orientations librating around anti-alignment, and use this system to place constraints on the properties of their birth protoplanetary disk. We follow the proposal by Petrovich, Wu, & Ali-Dib (2019) that these planets have been placed on these orbits as a natural result of the precessional effects of a dissipating massive disk and extend it by using direct N-body simulations and models for the evolution of the gas disks, including photoevaporation. Based on a parameter space exploration, we find that in order to reproduce the system the initial disk mass had to be at least 95 M_Jup and dissipate on a timescale of at least 10^4 yr. This mass is consistent with the upper end of the observed disk masses distribution, and the dissipation timescale is consistent with photoevaporation models. We study the properties of such disks using simplified 1D thin disk models and show that they are gravitationally stable, indicating that the two planets must have formed via core accretion and thus prone to disk migration. We hence finally investigate the sensitivity of this mechanism to the outer planet's semi major axis, and find that the nearby 7:1, 8:1, and 9:1 mean-motion resonances can completely quench this mechanism, while even higher order resonances can also significantly affect the system. Assuming the two planets avoid these high order resonances and/or close encounters, the dynamics seems to be rather insensitive to planet c semi major axis, and thus orbital migration driven by the disk.

Explore related subjects

astro-ph.EP

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Mohamad Ali-Dib, Cristobal Petrovich. 2020-09-14. Constraining protoplanetary disks with exoplanetary dynamics: Kepler-419 as an example. https://doi.org/10.1093/mnras%2Fstaa2820

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Volcanic Satellites and Ion Escape in the Magnetospheres of Ultra-Cool and Brown Dwarf Stars

Radio emissions at $\sim$ GHz frequencies of ultra-cool dwarf and brown dwarf stars suggest the presence of radiation belts not unlike Jupiter's. We investigate the possibility the inferred magnetospheric plasma at the primary star is sourced by an active planet or via ion escape modeled as a weak ionospheric outflow. We consider indirect methods to estimate the magnetospheric plasma mass flow from auroral radio emission and apply them to the ultra-cool dwarf LSR J1835+3259. We find that an ionospheric outflow is a viable source of the order of $10^{5}$ kg s$^{-1}$, if the ionospheric effective Pedersen conductance is lower than $\sim 0.02$ mho. On the other hand, a tidally-heated volcanic satellite with the same mass and radius as Io and an orbit with a semimajor axis lower than about $10$ stellar radii, whose eccentricity ($e \sim 10^{-3}$) is maintained by perturbations by other planets in the system, is found to be a viable source of magnetospheric plasma without strong limitations on the ionospheric conductance. The volcanic satellite scenario is also naturally in sync with the recent finding that ultra-cool dwarfs with distant substellar or stellar companions are remarkably more likely to be detected as radio emitters.

astro-ph.EP↗
arXiv2026

Tidal Demise: The Evolution and Fate of a Hypothetical Venus Moon

Venus possesses no natural satellite, raising the question whether a formed moon could have survived. We explore the tidal evolution of a Venus-moon system, coupling Venus's spin to the satellite's orbit under tides from the moon and Sun. We survey spin period ($P_0 = 5$--100~hr), moon mass ($M_m = 0.01$--$10~M_{\rm Moon}$), eccentricity, quality factor, and initial semi-major axis under both constant-$Q$ and constant time lag models. Survival depends on competition between outward migration ($\propto M_m$) and synchronous radius expansion ($\propto M_m^2$): for circular orbits around rapidly spinning Venus ($P_0 \lesssim 12$~hr), a lunar-mass satellite survives the age of the Solar System in both models. For $P_0 \lesssim 10$~hr, eccentricity pumping can destabilize low-mass satellites, while for $P_0 \gtrsim 15$~hr or $M_m \gtrsim 2~M_{\rm Moon}$ the synchronous radius overtakes the orbit and drives Roche destruction within $\sim$0.03--1.7~Gyr in the constant-$Q$ model. The constant time lag model instead permits quasi-synchronous survival for massive moons at fast spin. Explaining Venus's present state requires satisfying two constraints simultaneously: loss of the satellite and despinning of an initially rapid rotator. Both are met only within a restricted region of parameter space, favoring moderate post-impact spin periods and lunar-to-super-lunar masses. Giant impact simulations predict spin periods $\gtrsim$12~hr for Venus's present rotation, placing a lunar-mass satellite at the survival boundary. For last-impact conditions within this region, the present absence of a Venusian satellite arises through tidal evolution alone; a subsequent catastrophic stripping event, while capable of removing a moon, is not required.

astro-ph.EP↗
arXiv2026

Evidence for an Extended Hydrogen Outflow on WASP-12 b

Recent observations of atmospheric escape from planets orbiting early-type stars indicate that planets with higher Roche filling factors have significantly higher mass loss rates. For three of these planets, full-orbit observations have revealed the presence of large leading and trailing tails of escaping planetary material. These 3D outflow geometries encode information about the underlying outflow physics, and can also be used to constrain their stellar wind properties and to predict their long-term orbital evolution. We present new evidence for extended H$α$ and H$β$ absorption from escaping hydrogen for a fourth planet, WASP-12 b. We observed WASP-12 b with the Keck Planet Finder on Keck I over a period of approximately eight hours centered on the transit. We find a H$α$ and H$β$ absorption signal in the stellar rest frame that is strongest during the transit (H$α$ amplitude: $2.66\pm0.25\%$, H$β$ amplitude: $2.88\pm0.43\%$), with evidence of both pre- and post-transit absorption. This measurement is consistent with outflow models where the escaping gas overflows the planet's Roche lobe and is advected into the stellar rest frame before being tidally sheared into extended tails. This outflow behavior is qualitatively similar to previous H$α$ observations of this planet as well as observations of extended outflows from other gas giants orbiting early-type stars.

astro-ph.EP↗