Water worlds? Updated masses for TRAPPIST-1 planets

Artist’s conception of some of the planets in the TRAPPIST-1 planetary system. Image Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org)

There is an interesting new paper out about the seven near-Earth-sized exoplanets orbiting the star TRAPPIST-1. According to the study, four of the planets may be true water worlds, although just what form those may take isn’t clear. All seven planets are close in size to the Earth, with some of them in the star’s habitable zone, where temperatures could allow liquid water on rocky surfaces.

From the paper:

“The newly detected TRAPPIST-1 system, with seven low-mass, roughly Earth-sized planets transiting a nearby ultra-cool dwarf, is one of the most important exoplanet discoveries to date… Figure 4 indicates that – to within the errors of our determinations – the four most distant planets are consistent with pure water compositions, and in any event, are substantially less dense either Mars or Venus… The planets orbiting TRAPPIST-1 arguably constitute the most important exoplanetary system yet discovered. The planets’ large observed transit depths, coupled with the occurrence of extensive transit timing variations, present an extraordinary opportunity to discern the masses, the densities, the compositions, and the dynamical architecture of low-mass worlds. As more data are collected, substantial insights will be gained by an evolving comparison of these newly detected planets to the familiar terrestrial worlds of our own Solar System.

It will be interesting to see what further studies reveal. More information on the TRAPPIST-1 planets, including observations by Kepler, is here and here.

2 thoughts on “Water worlds? Updated masses for TRAPPIST-1 planets

  1. Any sentient life on one of those planets (2? 3? …) would have an enormous incentive to develop space-faring technology to get to and inhabit the other worlds in their system. They might not even need special breathing equipment on a similarly sized water world. And this is before knowing about the possibility of life-bearing moons too. Gee, with somewhat better telescopes, maybe we can detect objects traveling between worlds with non-elliptical paths, i.e. spaceships….

  2. Planet h is now UNQUESTIONABLY the most bizarre planet discovered to date. with a most likely mass of LESS THAN ONE TENTH THAT OF EARTH, and a radius exactly halfway between Mars and Earth, It CANNOT be the spherical “iceball” with little to no atmosphere as it is usually potrayed in artistd renditions. Neither can it be a MINI “mini-neptune” with a predominantly Hydrogen atmosphere. With a surface gravity THAT LOW combined with the ABSOLUTELY BRUTAL FLARING going on(extreme NOW according to Kepler data, and PROBABLY MUCH WORSE 3 billion years ago in its infancy, ALL OF ITS HYDROGEN MUST HAVE ESCAPES LONG AGO! What remains is something out of science fiction(LITERALLY: Robert Forward’s “Rocheworld”)! Due to its ridiculously LOW surface gravity(less than the MOON’s), TRAPPIST-1’s gravity pulls the starward hemosphere of TRAPPIST-1h TOWARD IT, forming a Fabrege egg-shaped “Eau Lobe”. Despite its 167K frigid temperature, the majority of its atmosphere would MIGRATE to the stellar point, providing an “insulating blanket” sufficient to keep the stellar point water in a permanently liquid form. The atmospheric surface pressure would be something akin to the surface pressure at the bottom of Challenger Deep in the Pacific Ocean. However, the surface pressure would be more akin to that of Venus at the terminator, and similarto our own at the anti-stellar point. If the atmosphere consists primarily of Oxygen, Carbon Dioxide, and Water vapor, there could even be an ice sheet at the anti-stellar point! SCIENCE FICTION WRITERS: GO NUTS!!!

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