Fast Litho-panspermia in the Habitable Zone of the TRAPPIST-1 System

Krijt, Sebastiaan; Bowling, T. J.; Lyons, Richard; Ciesla, F. J.

doi:10.3847/2041-8213/aa6b9f

Cited by 18 publications

(16 citation statements)

References 23 publications

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“…In addition, planets may have formed outside the HZ and escaped the brunt of the long and intense pre-main-sequence phase of M-dwarfs, before eventually migrating inwards into the HZ at a later stage; see Tamayo et al (2017) and Ormel et al (2017). Finally, M-dwarf planetary systems might possess inherent advantages such as the enhanced transport of life between planets via lithopanspermia by several orders of magnitude compared to the Earth-Mars system (Steffen and Li, 2016;Lingam and Loeb, 2017c;Krijt et al, 2017). However, in each of the above instances, either a high degree of fine tuning might be required or the feasibility of the proposed mechanisms remains indeterminate.…”

Section: Discussionmentioning

confidence: 99%

Colloquium: Physical constraints for the evolution of life on exoplanets

Lingam

Loeb

2019

Rev. Mod. Phys.

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Recently, many Earth-sized planets have been discovered around stars other than the Sun that might possess appropriate conditions for life. The development of theoretical methods for assessing the putative habitability of these worlds is of paramount importance, since it serves the dual purpose of identifying and quantifying what types of biosignatures may exist and determining the selection of optimal target stars and planets for subsequent observations. This Colloquium discusses how a multitude of physical factors act in tandem to regulate the propensity of worlds for hosting detectable biospheres. The focus is primarily on planets around low-mass stars, as they are most readily accessible to searches for biosignatures. This Colloquium outlines how factors such as stellar winds, the availability of ultraviolet and visible light, the surface water and land fractions, stellar flares, and associated phenomena place potential constraints on the evolution of life on these planets.

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Section: Discussionmentioning

confidence: 99%

Colloquium: Physical constraints for the evolution of life on exoplanets

Lingam

Loeb

2019

Rev. Mod. Phys.

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“…While we expect that high-velocity ejecta may reach neighbouring planets (e.g. in a Panspermia-manner, Krijt et al 2017;Lingam & Loeb 2017), most of the material in the torus would interact with the planet it has been ejected from. We note that for an Earth-like planet on a slightly wider orbit than planet h, the escape velocity (of about 10km/s) could become greater than the planet's Keplerian velocity and thus the material would not form a torus but rather be ejected on unbound orbits.…”

Section: Volatiles That Are Ejected Of the Atmosphere And Reaccreted mentioning

confidence: 95%

Cometary impactors on the TRAPPIST-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, and h

Kral

Wyatt

Triaud

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The TRAPPIST-1 system is unique in that it has a chain of seven terrestrial Earth-like planets located close to or in its habitable zone. In this paper, we study the effect of potential cometary impacts on the TRAPPIST-1 planets and how they would affect the primordial atmospheres of these planets. We consider both atmospheric mass loss and volatile delivery with a view to assessing whether any sort of life has a chance to develop. We ran N-body simulations to investigate the orbital evolution of potential impacting comets, to determine which planets are more likely to be impacted and the distributions of impact velocities. We consider three scenarios that could potentially throw comets into the inner region (i.e within 0.1au where the seven planets are located) from an (as yet undetected) outer belt similar to the Kuiper belt or an Oort cloud: Planet scattering, the Kozai-Lidov mechanism and Galactic tides. For the different scenarios, we quantify, for each planet, how much atmospheric mass is lost and what mass of volatiles can be delivered over the age of the system depending on the mass scattered out of the outer belt. We find that the resulting high velocity impacts can easily destroy the primordial atmospheres of all seven planets, even if the mass scattered from the outer belt is as low as that of the Kuiper belt. However, we find that the atmospheres of the outermost planets f, g and h can also easily be replenished with cometary volatiles (e.g. ∼ an Earth ocean mass of water could be delivered). These scenarios would thus imply that the atmospheres of these outermost planets could be more massive than those of the innermost planets, and have volatilesenriched composition.

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“…This has a wide range of implications, not only for the acceleration of Martian meteorites, but also for material exchange amongst planetary bodies in satellite systems, including the Earth-Moon, Mars-satellites, Jovian, Saturnian, and Pluto-Charon systems [e.g., Artemieva and Ivanov, 2004;Artemieva and Lunine, 2005;Stern, 2009;Chappaz et al, 2013;Ramsley and Head, 2013;Porter and Grundy, 2014]. In addition, our numerical models may have astrobiological implications, such as for the Panspermia [e.g., Melosh, 2003;Burchell et al, 2003;Price et al, 2013;Krijt et al 2017;Lingam and Loeb, 2017].…”

Section: Geological Implicationsmentioning

confidence: 99%

Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites

Kurosawa¹,

Okamoto²,

Genda³

2018

Icarus

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Hypervelocity ejection of material by impact spallation is considered a plausible mechanism for material exchange between two planetary bodies. We have modeled the spallation process during vertical impacts over a range of impact velocities from 6 to 21 km/s using both grid-and particle-based hydrocode models. The Tillotson equations of state, which are able to treat the nonlinear dependence of density on pressure and thermal pressure in the strongly shocked matter, were used to study the hydrodynamicthermodynamic response after impacts. The effects of material strength and gravitational acceleration were not considered. A two-dimensional time-dependent pressure field within a 1.5-fold projectile radius from the impact point was investigated in cylindrical coordinates to address the generation of spalled material. A resolution test was also performed to reject ejected materials with peak pressures that were too low due to artificial viscosity. The relationship between ejection velocity v eject and peak pressure P peak was also derived. Our approach shows that "late-stage acceleration" in an ejecta curtain occurs due to the compressible nature of the ejecta, resulting in an ejection velocity that can be higher than the ideal maximum of the resultant particle velocity after passage of a shock wave. We also calculate the ejecta mass that can escape from a planet like Mars (i.e., v eject > 5 km/s) that matches the petrographic constraints from Martian meteorites, and which occurs when P peak = 30-50 GPa.Although the mass of such ejecta is limited to 0.1-1 wt% of the projectile mass in vertical impacts, this is sufficient for spallation to have been a plausible mechanism for the ejection of Martian meteorites. Finally, we propose that impact spallation is a plausible mechanism for the generation of tektites.

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Fast Litho-panspermia in the Habitable Zone of the TRAPPIST-1 System

Cited by 18 publications

References 23 publications

Colloquium: Physical constraints for the evolution of life on exoplanets

Colloquium: Physical constraints for the evolution of life on exoplanets

Cometary impactors on the TRAPPIST-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, and h

Hydrocode modeling of the spallation process during hypervelocity impacts: Implications for the ejection of Martian meteorites

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