The TRAPPIST-1 solar system not bombarded by space rocks like early Earth, study suggests


Oct 22, 2019
Reference paper cited in this article, An upper limit on late accretion and water delivery in the TRAPPIST-1 exoplanet system,, 25-Nov-2021. "Abstract The TRAPPIST-1 system contains seven roughly Earth-sized planets locked in a multiresonant orbital configuration1,2, which has enabled precise measurements of the planets’ masses and constrained their compositions3..."

Very interesting reading here on TRAPPIST-1 system. My observation. This model report places constraints on giant impacts and heavy bombardment episodes in the protoplanetary disk postulated to exist at TRAPPIST-1 when the 7 exoplanets slowly evolved, yet now must evolve within a 3-million-year time span or shorter and no heavy bombardment or giant impacts like our solar system. Episodes of giant impacts and heavy bombardments result in the TRAPPIST-1, 7 exoplanet system orbiting very differently than their present orbital configurations and resonances around the parent star. Other new models reported for the TRAPPIST-1 system show the initial protoplanetary disk mass must be more than 13,000 earth masses to explain how the 7 exoplanets orbit the parent star in such a flat plane today. With such a large, postulated protoplanetary disk mass at TRAPPIST-1, I would think giant impacts and heavy bombardments episodes would be the norm when the 7-planet system evolved, accreting from the postulated spinning disk. Comparing TRAPPIST-1, 7 exoplanet system to our solar system and the MMSN used to explain our solar system’s origin, disclose real challenges in explaining planetary origins., reference paper cited, How Flat Can a Planetary System Get? I. The Case of TRAPPIST-1,, 03-June-2021. "Abstract The seven planets orbiting TRAPPIST-1 in a compact near-resonant chain offer a unique case to study in planet formation theory."

My observation. The report states the disk mass used in this new model is 0.04 solar masses or 13317.71 earth masses. Applying the MMSN to TRAPPIST-1 host star of 0.08 solar masses, the total disk mass of dust and gas could be 266 earth masses. A 266-earth mass protoplanetary disk around a red dwarf star of 0.08 solar masses is a canonical model approach. The model disk mass used in the report is more than 13,000 earth masses. This is much larger than the postulated, Minimum Mass Solar Nebula (MMSN) disk mass of about 3300 earth masses used for our solar system. The TRAPPIST-1, 7 exoplanet system is well studied. The total mass documented now in the TRAPPIST-1 system is 5.591 earth masses found in the 7 exoplanets observed. In contrast, our solar system has about 447 earth masses documented from Mercury to Pluto (Allen’s Astrophysical Quantities Fourth Edition, 2000, p. 293.).

Consider the orbital period for the largest member of TRAPPIST-1 system, TRAPPIST-1 c, 2.4218233 days. Using my astronomy calculator and plugging in the values for exoplanet mass, host star mass, semi-major axis= 0.01521 AU, e=0, I get an orbital period 2.4224 days. The number of orbital revolutions could be 1.5078E+11 or more than 150 billion revolutions around the host star in one billion years. Mercury in our solar system could complete 4.15 billion revolutions in one billion years. TRAPPIST-1 system has no protoplanetary disk observed today, apparently, we have no meteorites radiometrically dated from this system, and some or all the exoplanets at TRAPPIST-1 could complete hundreds of billions of revolutions around the host star using the age dates assigned to the system.

How gas clouds evolve into people like in our solar system encounters challenges it seems.



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