The sun may have hosted its own ‘alien megastructure’ in the past. The infamous star that caught the world’s attention earlier this year may play host to debris streaming from a destroyed protoplanet. If that’s the case, then destroyed objects early in the life of the solar system could have grabbed extraterrestrial attention in the past.
Last fall, the star KIC 8462852 gained fame when researchers announced that an ‘alien megastructure’ could be responsible for the strange dimming of the star. While some have suggested that a swarm of comets could be responsible for the signal, others have pointed out that the sheer number of objects makes the comets unlikely culprits.
Recent research offers another suggestion. In addition to the comet swarm, Eva Bodman and Alice Quillen, both at the University of Rochester in New York, suggested that the disruption of a Ceres-sized object could reproduce the signal. While scientists are hardpressed to find enough comets dancing in tandem, the debris from a destroyed protoplanet should more or less stick together in its orbit around the sun.
I spoke with Eva Bodman at the American Astronomical Society’s Division on Dynamical Astronomy earlier this year about the difference between comets and a destroyed planetary body. If the object formed farther out in the solar system, where ices freeze, then telling them apart could be difficult, as both would be made up of rock and ice.
The comet swarm has been hotly debated. In a previous paper, the pair estimated that it would take 36 200-kilometer-sized comets to produce a single dip. Using their numbers, Bradley Schaefer, of Louisiana State University, estimated that it would take 648,000 comets to produce the dimming over the course of a century.
In their recent research, Bodman and Quillan found that a group of comets orbiting roughly every 30 years could explain the dips. They suggested that an unseen companion could have the potential to herd the comets together to create a swarm. Another possibility is that the star is observed in a state similar to the Late Heavy Bombardment period, with leftover debris in the system causing the dips.
If a growing young planet had been destroyed, it could also provide the material for the unusual signal, the researchers found. Bodman told me that a giant planet could have potentially shredded a smaller sibling, creating the rubble pile orbiting KIC 8462852. The debris would gradually spread out over time, eventually dispersing.
I love to apply things to the solar system, so follow me down my random musings. Several studies have suggested that our sun once hosted more baby planets than the official 8 that grew to adulthood. David Nesvorney has proposed a baby ice giant that was booted out of the solar system (That booted planet didn’t become Planet 9; I asked. More on that in my upcoming article in Astronomy magazine.) Brett Gladman and Kat Volk suggested that the solar system could once have collected a series of tightly-packed inner planets (STIPs), with most booted into the sun.
The movement of planets around the sun may also mean that Ceres formed in the region of the giant planets and traveled inward. If that’s the case, it probably wasn’t the only one; statistically speaking, it’s unlikely the asteroid belt captured 100% of the Ceres-objects that formed. If one of Ceres siblings drifted too close to Jupiter or the sun, it could have been disrupted and created its own structure.
All of that, of course, is conjuncture; Bodman’s only reference to the solar system was to compare the mass of the potentially disrupted world to Ceres. Still, it’s kind of cool to consider that the rash of failed planets in the solar system could have puzzled alien astronomers billions of years before life ever formed on Earth.