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The TRAPPIST-1 Star System Is Alive With the Sound of Music

“The goal is try to convert as many things in space into music as possible.”

by Becky Ferreira
May 10 2017, 6:52pm

Concept art of TRAPPIST-1. Image: ESO/M. Kornmesser

When scientists announced the discovery of a whopping seven Earth-scale worlds in orbit around the TRAPPIST-1 star system back in February, space nerds understandably went bonkers with delight. Located just 39 light years away—practically next door in cosmic terms—this ultracool red dwarf star and its wealth of tantalizing worlds suddenly became a prime destination for further exploration.

Now, Toronto-based astrophysicists have sweetened the exoplanetary pot with their creative musical simulation of the system's unusual orbital dynamics. Matt Russo, a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics (CITA), partnered with Daniel Tamayo, a post-doc at both CITA and the University of Toronto Scarborough's Centre for Planetary Science, to translate the orbital periods of TRAPPIST-1's seven worlds into harmonious pitches.

The result is this lively tune, composed by the cosmos itself, which would make a great first track on a playlist curated for any future interstellar missions to TRAPPIST-1.

The Song of a Solar System: TRAPPIST-1. Video: Thought Cafe/YouTube

As visualized in the above simulation, a piano note is played every time one of the system's planets transits—or passes in front of—its host star from our perspective on Earth. The composition begins with the outermost planet, TRAPPIST-1h, and builds with the addition of each world. Drum beats are introduced at moments when the swifter inner worlds lap their slower outer neighbors. The song fades out with an accelerated version of the red dwarf's lightcurve, the star's oscillating brightness over time, based on data collected by the Kepler space telescope.

Read More: Ultra-Cool Dwarf Stars May Host Planets With Ultra-Cool Life

TRAPPIST-1 makes beautiful music because each planet happens to line up in a "resonant chain." Two orbits of the outermost planet have an equal period to three orbits of the sixth planet, four orbits of the fifth planet, six orbits of the fourth planet, nine orbits of the third planet, 15 orbits of the second planet, and 24 orbits of the innermost world, TRAPPIST-1b.

GIF: Thought Cafe/YouTube

Tamayo is the lead author of a new study in the Astrophysical Journal Letters about this utterly unique orbital jam band, and how it might relate to the system's formation, stability, and longevity.

"TRAPPIST has the longest resonant chain of any planetary system that has ever been discovered," Tamayo told me over the phone. "It's exciting, tentative evidence that maybe around low-mass stars, the formation process is much more gentle and better able to make these configurations than around high-mass stars."

The Song of a Solar System: TRAPPIST-1. Video: Thought Cafe/YouTube

Russo, who is a musician, scaled up the system's natural frequencies 212 million times, so that they could be heard by the human ear. For comparison, he tried this technique out on Kepler 90, a Sunlike star that also hosts seven planets, none of which are in resonance. This system failed its audition by churning out a chaotic jumble of notes.

Tamayo, Russo, and fellow musician Andrew Santaguida have started a website, SYSTEM Sounds, where they plan to "try to convert as many things in space into music as possible," Russo told me.

"But nothing will be nearly as easy as TRAPPIST," he said. "With any other system, it will be hard to get something as beautiful. That's what's so special about TRAPPIST."

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