The Origins of Super Jupiter TOI-2145b: An Analysis of its Moderately Eccentric and Nearly Aligned Orbit

Core Concepts

The formation process of super Jupiters, massive planets several times the size of Jupiter, remains a subject of debate, with two primary theories: formation through collisions of smaller planets or inherent formation with high mass. This study investigates the warm super Jupiter TOI-2145b, analyzing its orbital characteristics to shed light on its formation history and the broader implications for understanding super Jupiter origins.

Abstract

Bibliographic Information:

Dong et al. (2024). Origins of Super Jupiters: TOI-2145b Has a Moderately Eccentric and Nearly Aligned Orbit. The Astronomical Journal.

Research Objective:

This research paper investigates the origins of super Jupiters, focusing on the specific case of TOI-2145b. The authors aim to determine whether this warm super Jupiter formed with its high mass or acquired it through collisions with other planets.

Methodology:

The study utilizes a combination of observational data and N-body simulations. The researchers analyze TESS transit data, HIRES radial velocity measurements, and new NEID Rossiter-McLaughlin effect data to characterize the orbital properties of TOI-2145b. They then conduct N-body simulations, exploring two formation scenarios: a low disk mass scenario with subsequent planet collisions and a high disk mass scenario with minimal collisions.

Key Findings:

The analysis reveals that TOI-2145b is a 5.7 Jupiter-mass planet with a moderate orbital eccentricity (e = 0.21) and a nearly aligned orbit (λ = 6.8°). The N-body simulations demonstrate that both formation scenarios could potentially explain the observed properties of TOI-2145b. However, the simulations suggest that super Jupiters formed through collisions tend to have a narrower eccentricity distribution compared to those formed with inherently high masses.

Main Conclusions:

While both formation scenarios remain plausible for TOI-2145b, the authors propose that the collisional formation pathway might be more consistent with the observed eccentricity distribution of the broader warm Jupiter population. They highlight the need for further observations, particularly the search for companion planets, to distinguish between the two formation scenarios.

Significance:

This research contributes to our understanding of the formation and evolution of planetary systems, particularly the processes leading to the creation of super Jupiters. The findings emphasize the importance of considering both in-situ formation and collisional pathways when studying these massive planets.

Limitations and Future Research:

The study acknowledges limitations in the precision of radial velocity measurements due to the host star's high rotation rate. Future research could benefit from improved radial velocity data and observations with higher precision to refine the orbital parameters of TOI-2145b and search for potential companion planets. Additionally, expanding the N-body simulations to explore a wider range of initial conditions and disk mass distributions would provide a more comprehensive understanding of super Jupiter formation.

Stats

TOI-2145b has a mass of 5.68+0.37−0.34 MJup.
TOI-2145b has a moderate orbital eccentricity of e = 0.214+0.014−0.014.
TOI-2145b has a projected stellar obliquity of λ = 6.8+2.9−3.8 degrees.
TOI-2145b has an orbital period of P = 10.261128+0.000009−0.000007 days.
TOI-2145b has a semi-major axis of a = 0.1117+0.0035−0.0034 au.
TOI-2145b has a planet-star separation of a/R⋆= 8.74+0.16−0.14.
TOI-2145b has a radius of Rp = 1.092+0.030−0.028 RJup.

Quotes

"Super Jupiters are giant planets with several Jupiter masses. It remains an open question whether these planets originate with such high masses or grow through collisions."
"Previous work demonstrates that warm super Jupiters tend to have more eccentric orbits compared to regular-mass warm Jupiters. This correlation between mass and eccentricity may indicate that planet-planet interactions significantly influence the warm giant planet demographics."
"Our N-body simulations suggest that the formation of super Jupiter TOI-2145b could involve either of two scenarios: a high initial mass or growth via collisions. On a population level, however, the collision scenario can better describe the mass-eccentricity distribution of observed warm Jupiters."

Key Insights Distilled From

Origins of Super Jupiters: TOI-2145b Has a Moderately Eccentric and Nearly Aligned Orbit

by Jiayin Dong,... at arxiv.org 11-05-2024

https://arxiv.org/pdf/2411.01356.pdf

Deeper Inquiries

How might the presence of a protoplanetary disk influence the formation and migration of super Jupiters?

The presence of a protoplanetary disk plays a crucial role in the formation and migration of super Jupiters. Here's how:
Formation:

Core Accretion and Disk Instability: Super Jupiters are thought to form through either core accretion or disk instability.

Core accretion involves the formation of a massive core of rock and ice, which then rapidly accretes gas from the surrounding disk. A massive disk provides ample material for both core formation and gas accretion, increasing the likelihood of forming a super Jupiter.
Disk instability occurs when the disk itself becomes gravitationally unstable and fragments, directly forming a giant planet. This process is more likely in massive, cold disks.

Pebble Accretion: This mechanism, involving the accretion of centimeter-sized pebbles, can significantly speed up the core formation process, making the formation of super Jupiters more efficient in disks rich in solid material.
Migration:

Type II Migration: Once formed, giant planets like super Jupiters can migrate inwards through the disk via Type II migration. This occurs when the planet is massive enough to carve a gap in the disk and migrate inwards along with the viscous evolution of the disk. The speed and extent of migration depend on the disk's properties, such as its density and viscosity.
Planet-Disk Interactions: The disk can also influence a planet's orbital eccentricity. Interactions with the disk can either damp or excite eccentricity, depending on the disk's properties and the planet's mass and orbital parameters.
In summary, a massive protoplanetary disk provides the necessary conditions for the formation of super Jupiters, either through core accretion, disk instability, or a combination of both. The disk also plays a crucial role in the planet's subsequent migration and orbital evolution, potentially shaping its final orbital configuration.

Could TOI-2145b's current orbital configuration be a transient stage in its evolution, and might its eccentricity and inclination change significantly over time?

Yes, it's highly plausible that TOI-2145b's current orbital configuration is a transient stage in its evolution. Both its eccentricity and inclination could change significantly over time due to various dynamical processes:

Secular Interactions: Even without close encounters, planets in a multi-planet system can interact gravitationally over long timescales through secular interactions. These interactions can exchange angular momentum and energy between planets, leading to changes in their orbital eccentricities and inclinations.
Future Planet-Planet Scatterings: While TOI-2145b's current moderate eccentricity might suggest a history of gentle migration or collisions, future close encounters with other planets in the system (if any) cannot be ruled out. Such scatterings can significantly alter the planet's eccentricity and inclination, potentially even leading to ejection from the system.
External Perturbers: The presence of a distant stellar companion or a yet-undetected massive planet in the outer regions of the system could also perturb TOI-2145b's orbit over long timescales. This could lead to oscillations in its eccentricity and inclination.
Tidal Effects: While tidal forces from the host star are likely weak at TOI-2145b's current orbital distance, they can still play a role over very long timescales. Tidal interactions can gradually circularize the planet's orbit and align its spin axis with its orbital axis.
Given these factors, it's crucial to consider TOI-2145b's current orbital configuration as a snapshot in time. Long-term monitoring of the system, particularly radial velocity measurements to search for additional companions, is essential to understand its dynamical history and predict its future evolution.

If super Jupiters predominantly form through collisions, what implications does this have for the potential habitability of planets in these systems?

If super Jupiters predominantly form through collisions, it would have significant implications for the potential habitability of planets in these systems, generally painting a less optimistic picture:

Dynamical Upheaval: The collisional formation of a super Jupiter would likely cause significant dynamical upheaval in the system. The process of scattering and merging of planets would disrupt the orbits of any pre-existing planets in the system, potentially ejecting them or pushing them into the host star.
Habitability Zone Disruption: Even if planets survive the initial formation period, the presence of a massive, often eccentric super Jupiter can disrupt the stability of the habitable zone. Gravitational perturbations from the super Jupiter can alter the orbits of planets in the habitable zone, making it difficult for them to maintain stable, temperate climates suitable for life.
Delivery of Volatiles: While giant planet migration can deliver volatiles like water to the inner regions of a planetary system, potentially aiding habitability, the violent nature of collisions might counter this effect. Collisions could strip planets of their atmospheres and volatiles, making them less hospitable to life.
However, it's important to note that:

System Architecture Matters: The specific impact on habitability depends heavily on the system's architecture, including the super Jupiter's orbital parameters and the presence of other planets. Some systems might still harbor habitable planets in stable orbits despite the presence of a super Jupiter.
Alternative Formation Pathways: Not all super Jupiters may form through collisions. Some might form in situ or migrate inwards more gently, potentially having a less detrimental effect on habitability.
In conclusion, while the collisional formation of super Jupiters presents challenges for habitability, it doesn't necessarily preclude it entirely. Further research, particularly characterizing the architectures of super Jupiter systems and understanding their formation pathways, is crucial to assess the true impact on the potential for life in these systems.