Home Exoplanets Astronomers find a new inexplicable “Tabby’s Star” in Random Transiter

Astronomers find a new inexplicable “Tabby’s Star” in Random Transiter

This artist's concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. | Image: NASA/JPL

A star with mysterious planet-type transits lacking periodicity has been newly identified, and so far, astronomers don’t have a clear explanation for the data. Comparisons are now being drawn to the infamous “Tabby’s Star”, an F-class main sequence star with strange light dips that had some skywatchers suggesting the presence of intelligent alien life after its discovery. The new star’s official name is HD 139139, so far nicknamed “The Random Transiter” (RT), and it was discovered using data from NASA’s Kepler telescope’s secondary mission, K2, which showed 28 transit-like events over the course of an 87-day observation. RT is located about 350 light years away in the constellation Libra.

After studying the dips in light from RT and analyzing their data in comparison to other known astronomical objects and phenomena, a team of astronomers led by Professor Saul Rappaport of the Kavli Institute for Astrophysics and Space Research at MIT have published a paper in the Monthly Notices of the Royal Astronomical Society outlining their assessments and results. The abstract of the study lays out both their conclusions and the star’s overall mystery:

The unusual aspect of these dips, all but two of which have depths of 200 ± 80 ppm, is that they exhibit no periodicity, and their arrival times could just as well have been produced by a random number generator… We explore a number of ideas for the origin of these dips… All transit scenarios that we have been able to conjure up appear to fail, while the intrinsic stellar variability hypothesis would be novel and untested.

The paper laid out a few possible explanations for the oddities found which were tested, including:

  • Planet transits in a multiplanet system
  • Planets orbiting both stars A and B
  • Few-planet system with huge transit-timing variation (TTV)
  • Disintegrating planet with only rare transits appearing
  • Debris disk of dust-emitting asteroids
  • Eccentric planet orbit about one star in a close binary – S-type
  • P-type circumbinary planet
  • Dipper-like activity
  • Short-lived star spot

However, each explanation was found wanting. “We find that none of these, though intriguing, is entirely satisfactory,” the paper concluded. The next steps for Random Transiter are dependant on the broader scientific community. In order to investigate further, resources are required such as telescope time. The research paper expresses this need specifically:

The purpose of this paper is largely to bring this enigmatic object to the attention of the larger astrophysics community in the hope that (i) some time on larger telescopes, or ones with high photometric precision, might be devoted to its study, and (ii) some new ideas might be generated to explain the mysterious dips in flux.

This possible planetary system has sparked interest similar to that of Tabby’s Star, the infamous star whose unusual fluctuations in light inspired alien megastructure theories (i.e., Dyson Sphere) for its behavior. The strangeness was discovered by citizen scientists participating on the website PlanetHunters.org, and further research on the star was funded via a crowdsourcing campaign on Kickstarter which found the dips were likely caused by orbiting clumps of dust. The dips in Random Transiter, though, are different still from even that case.

Dr. Hugh Osborne, a postdoctoral researcher at the Lab of Astrophysics of Marseille, runs a blog called “Lost in Transit” about exoplanet topics and had this to say about RT:

If anything, the coherent dips in this system look more like solid structures than the incoherent wandering of flux during the eclipses of Tabby’s star (though the orbital periods the transit durations suggest don’t really make sense for any solid structure).

Overall, alien dreamers may have the opportunity to hope once more for proof of life outside our solar system until more data becomes available to scientists and provides the more mundane explanation.


After the Tabby’s Star tease, it’s difficult to get too excited about anything along those lines being reported again, and not because I don’t think discovering alien technosignatures is possible. No matter what is found, nearly 100% of scientists will be out to kill the prospect of ET, and do it with a vengeance, even while they themselves can never be certain that it’s not. Take, for example, the dismissal that Tabby’s Star is just a clump of dust:

Dust is most likely the reason why the star’s light appears to dim and brighten. The new data shows that different colors of light are being blocked at different intensities. Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure,” Assistant Professor Tabitha Boyajian of Louisiana State University’s Department of Physics & Astronomy said about the new research conclusions.

Hidden between the lines of this statement is 1) they don’t actually know for sure that’s what’s causing the dips; and 2) they’re concluding it’s not aliens because apparently they know how alien tech would be built, i.e., opaque. This clip from NASA’s page on the topic says the same thing, even if its a bit harder to tell from the different language used:

Astronomers have found the dimming of the star over long periods appears to be weaker at longer infrared wavelengths of light and stronger at shorter ultraviolet wavelengths. Such reddening is characteristic of dust particles and inconsistent with more fanciful “alien megastructure” concepts, which would evenly dim all wavelengths of light.

Honestly, I’m not sure why alien solar panels would be opaque. If we’re talking about 22% dips in star light when the structures in the way aren’t opaque, there could be a fairly negative impact on the surrounding system if the light was totally blocked.

An artist’s depiction of Tabby’s Star. | Image: NASA

Imagine a greenhouse, for example. If you put opaque solar panels on top to run the heating or cooling system, you’re going to block the sunlight and defeat the purpose of the structure to an extent. If you are collecting your star’s energy via a Dyson Sphere, blocking sunlight to do that would be working against the purpose a bit. Here’s where semi-transparency comes in, or even full transparency where the tech would be better suited. Search on Google for “transparent solar panels” to see what Earthlings have already come up with.

The study itself does admit that there’s a lot more data and effort that needs to happen before they’re sure-sure:

All-in-all, the apparent low duty cycle of the dips, unclear predictions on when they will recur, and fairly unconstrained multiyear timescales of the long-term variability will require a committed, intensive monitoring program spanning the next decade and beyond.

Back to Dr. Osborne and Random Transiter for a minute, he does offer one alien-debunking suggestion that I do agree with:

Some also suggested searching for pi or prime numbers in the [RT] signals, but if an alien was trying to get our attention and had the ability to build structures 1.5 times larger than Earth at random orbital periods why wouldn’t they just, you know, send us a radio or laser pulse?

Then again, perhaps we haven’t figured out how to decode their radio or laser signals (or they’ve been reduced to cosmic static), and their structural engineers infused some math into the building plans…you know…just in case.

For more on Tabby’s Star, watch Professor Boyajian’s TED talk on the topic below: