A subtitle to this article could read something like “When Science Fiction becomes Science Fact” or “What happens to an astronomer’s brain from prolonged Oxygen deprivation-too many hours observing above 4.1 kilometers Altitude” or “Idea Suggestion Rejects for the next Netflix Sci-Fi Thriller” or “Everything that Isn’t Happening with KIC-8462852”.
A recently published paper regarding anomalous Kepler mission light curves associated with KIC-8462852 have prompted a deviation from normal SETI Institute observations. Now, SETI researchers, using the Allen Array to study the enigmatic F3 class main sequence star (“Main Sequence” refers to a “normal” star, a star in the relatively long-term evolutionary state where they’re producing energy through hydrogen fusion reactions in their core) in Cygnus have not found the telltale radio signature they were hoping for. The anomalous light curve exhibits flux variations consistent with, well, not much of what we’re used to. What, you may ask, prompted the SETI Institute to deviate from it’s regularly scheduled observations? Senior scientist at SETI, located in Mountain View, California, Dr. Gerald Harp, is quoted as saying “We either caught something shortly after an event like two planets crashing together or alien intelligence“. Apart from the missing Infrared flux arising from the aftermath of such an event, the “two planets crashing” part of his comment is a sensible possibility, consistent with the Kepler light curves. The “alien intelligence” part of his comment is, well, Freud, Star Trek, Independence Day and Ridley Scott’s “The Martian” all wrapped-up together. Perhaps, based on what SETI’s stated objective is, this comment is more an expression of hope and frustration, rather than anything based on real science.
An “Alien MegaStructure“? Really!? This idea has been put forth as real science; really, it has! First proposed by climate denying physicist Freeman Dyson, a Dyson Sphere is the Alien MegaStructure being suggested, a structure, either fully or partially enclosing an advanced civilization’s host star, designed to more fully harness the energy of the star! Now, the sun continually emits 3.85×10^26 Watts of power, that would be a 4 with 26 zeros trailing off to the right-Watts of power or Joules of Energy/second (Energy/Unit of time = Power). Of of that energy, if every square meter of the earth were covered with solar panels, we would be able to harness approximately 0.1 ExaJoules of energy (one ExaJoule = 1×10^18 Joules) every second of every day with existing technology (1 Watt = 1 Joule of Energy/second).
Global energy consumption, at 2010 levels, is scaled at hundreds of ExaJoules per year! In more meaningful terms, our civilization, at its current level of technology and energy consumption, requires in one year, 1 part in a million of what the sun produces every second and that energy could be provided in under an hour with existing technology! KIC-8462852, a more luminous F3-class star, has an intrinsic luminosity of 4.7 or almost 5x that of the sun. Said differently, if an alien civilization inhabiting a planet around that star needed even a partial Dyson Sphere for lack of necessary energy, its requirements would be 3.85x5x10^26 or 1.81 x 10^27 Joules of energy every second! Contrary to Dyson’s original premise, that as a civilization’s technical prowess increases, so does it’s energy requirements and hence the eventual need for the structure named in his honor, I would suggest that their technology would be such that they would make more efficient use of the available energy; this, rather than require ever more and more energy and the need to build such an absurd structure. It is beyond the scope of even the most far-reaching science fiction story that such a civilization, no matter how advanced, would require the full energy output of even a modest star, no less an F3 class star.
Fermi’s Paradox and the Alien Need for a Dyson Sphere
For the moment, let us indulge in this fantasy. If we’re really determined to make contact, we better take a long, hard look at the consequences of successful contact. As well, if it were necessary for them to construct a Dyson sphere, clearly illustrating their technical prowess and ravenous appetite for energy, that they would constantly require more and more, they would be looking elsewhere, at other stars; what would stop them from doing the same to star after star, like parasites spreading through the galaxy? For those who, waxing gleeful, entertain themselves with such fanciful notions as a successfully deployed Dyson sphere, remember that if such a civilization can accomplish this, you better hope they never find us as they would have about as much regard for us as we do for a colony of ants! Fermi’s Paradox openly poses the question “Our Galaxy Should Be Teeming With Civilizations, but where are they?”
Enter our Dyson Sphere-building alien civilization and remember, we’re wandering down fantasy lane at the moment. Suppose, millions of years ago, they beat the odds, survived their infancy as a civilization (something that, as a species, we’re struggling with now) and went on to flourish as an advanced, technical society. Suppose they continued to grow to a point where their energy requirements outstripped their planet’s ability to provide sufficient energy to satisfy their voracious appetite (this is Dyson’s original premise). Imagine they, somehow, were able to construct their first Dyson sphere around their home star, partially enclosing the planet of their origin in the process. The millennia went by and they were, again, facing a dearth of energy. Their first Dyson Sphere was insufficient so, having evolved technically, not morally, they started looking towards other stars. They are confronted with a technical imperative, not a moral one; in fact morality had been eliminated long ago, hundreds of millennia previous and there is only one mandate: survival at all costs. At this point, it is inconceivable that even a fraction of the 10^27 Watts of energy available to them through their existing Dyson sphere would be insufficient but lets entertain this for the moment. If their energy requirements were such that they needed more power than a 10^27 Watt aggregate power stream could provide, it’s a sure bet they’ve mastered interstellar travel and maybe this is the one reason they would need such tremendous amounts of energy. And so a contingent of them ventured out to the stars and, over the millennia, star after star, planetary system after planetary system fell prey to their voracious appetite for ever more energy and thus, millions of years after they began, there are no more civilizations left. And now, we’re the only ones left, the ones with the big mouths who can’t help themselves, the ones with this incurable, infantile need to “make contact” and, ending this segment on a more serious note, we do so at our own peril!
Imagine living inside a Dyson sphere, you may never see the stars again and there would be these ugly, perpetually visible rings or structures where we once looked up and saw the moon or the Milky Way.
F3 Class Star Not Suitable to sustain Life over the Long Term
Back to reality; the productive lifetime of a more luminous F3 class star is scaled at about 2 – 3 billion years or about 25% that of the sun’s productive lifetime. This time-frame is insufficiently short for life to begin, evolve and thrive such that a civilization could even begin, never mind thrive and flourish to become the dominant life form on the planet. It took life almost a billion years to begin here and then another 3.6 billion years more for evolution to produce us, the dominant species on the planet. After 2 billion years or so, an F3 class Main Sequence Star would have commenced helium burning, evolving off the Main Sequence to begin its Red Giant phase of evolution. If life evolves upward at a similar pace elsewhere as it did here, and there is no reason to indicate that it shouldn’t, evolution of an advanced life form would never have had a chance with such a star. In fact, if we’re serious about the Kepler Mission’s Prime Directive, to “Find Earth-like planets in the Habitable Zones of their host stars” (the habitable zone is the zone around every star where the conditions are such that water could exist in a liquid state), with the intention, ostensibly, to find life and thus, to complete the Copernican revolution, then we shouldn’t even be looking at stars whose luminosity is greater than the sun’s. In fact, our own star is just inside the high end of the stellar luminosity spread, the luminosity range within which we should be searching for an analog of ourselves, a star with similar age, mass and luminosity characteristics as our own star. Our star, the sun, is a Main Sequence G2 class star (G2V). We’ve only ascended to the top of the evolutionary ladder to become the dominant species on the planet 3.6 billion years after life first emerged here. This point on our timeline is half way through our star’s productive lifetime. We have about another 1.5 billion years left on this planet before the sun, as it ages normally, its luminosity increasing at a rate of 1% every 100 million years, produces a runaway greenhouse, making conditions for life increasingly hostile to the point where life simply can’t evolve to accommodate the sun’s continuously increasing luminosity. No matter how hardy, life, at one point in the distant future, will cease to exist here. And this happens long before the sun depletes its compliment of core hydrogen and evolves off the Main Sequence to become a red giant star. Having said that, the question begs asking, what star would be the “ideal star” where life could thrive and flourish for more than just a few billion years.
As already established, KIC-8462852 is an F3 Main Sequence star (full designation: F3V – the “V” indicates Main Sequence) and that it has a productive lifespan of 2 – 3 billion years. An F class star presents as yellow-white, being somewhat hotter and more luminous than our sun, an early G class main sequence star. An typical F class star that would be familiar to many would be the star Procyon, visible during the late fall through early spring. Known as Alpha Canis Minoris, Procyon is an F5 Main Sequence star (F5V) and is the brightest star in Canis Minor, the lesser dog. A read of the recently published paper, reveals an uncertainty in the rotation period of KIC-8462852 as determined by the authors: “This 0.88-day signal is a broad feature that resembles typical FTs [Fourier Transforms] of Kepler targets for early type stars (Balona 2013, see their figure 6). If this is a rotation period, then the projected rotational velocity (from Section 2.2) of 84.4 km/sec represents a minimum stellar radius of 1.46 solar radii, consistent with the radius of an F-type star” and “The projected rotational velocity we measure v sin i = 84.4 km/sec is also well in line with the one predicted from rotation in Section 2.1, if the 0.88 d signal is in fact the rotation period.”
It should be pointed out that if 0.88 days (21 hrs, 7 minutes) is the rotation period, it would be quite high and KIC-8462852 would be classified as a “rapid rotator“, a class of star that contains the famous, bright star, Vega. With a rotation speed of 275 km/sec, Vega completes one rotation in 10 hours, about twice that of KIC-8462852. Back in the first quarter of the 20th century, Hugo von Zeipel, working at Sweden’s Uppsala Observatory, developed the mathematical models and dynamics of these rapidly rotating stars. Known as the von Zeipel effect, a rapidly rotating star will present as an oblate spheroid with significantly flattened poles and a bulging equatorial region. The foreshortened polar radius will provide for a greater luminosity along the polar axis and the greater equatorial radius will provide for a diminished luminosity along the equator, effects that are directly related to the rapid rotation. The basic physics is easy to understand if one thinks of a star as a rotating super-heated plasma that behaves as a fluid. If the preferential direction of rotation is along the equatorial region, more of the material would be concentrated along the equator; at sufficiently high rotation rates, material will actually fly off as the rotational centripetal force is insufficient to keep the material bound together along the plane of motion. Known as the “breakup” velocity, the calculations are trivial and for Vega it is 403 km/sec, for KIC-8462852 it is 417 km/sec and for the sun it is 437 km/sec. Vega’s rotation speed is 275 km/sec or about 69% of the fly-off velocity, the rotation speed of KIC-8462852 is 84.4 km/sec or about 20% of its fly-off velocity and the sun’s rotation speed is approximately 25 days, no where near it’s fly-off speed. The rotation periods of both Vega and KIC-8462852 are scaled in terms of hours and the sun, in terms of weeks. Since there are differential luminosity effects associated with fast rotators, this may be a possible contributor to the anomalous light curves. That an 0.88 day rotation period is suggested with high confidence in the light curve data is significant and speaks to this as a possible cause for the anomalous light curves.
Alternative, More Reasonable Explanations
1) The absurdity of a Dyson sphere surrounding KIC-8462852, either operating or existing as a relic, not withstanding, no excess Infrared flux is observed. In fact, the star presents with nominal IR flux levels according to its effective temperature and evolutionary state. If a Dyson sphere were present, we would look for an IR excess, especially in the longer wavelength IR regimes. Even partially enclosing any star would result in excessive heating of the sphere with the corresponding IR signature. We observe no such signature. The paucity of IR flux also speaks against other suggested explanations such as planetary collisions which would also present with a characteristic IR signature. Planetary collisions have been postulated as a possible explanation for the anomalous light curves. Although this is a viable possibility, it should be noted that there would be an associated shortwave IR flux, albeit short lived with time frames scoped in days, possibly a week as the remaining bodies cool off. What are the chances that we observed this system during the immediate aftermath of such an event?
2) Since there are differential luminosity effects associated with fast rotating stars, this may be a possible contributor to the anomalous light curves, although unlikely. That an 0.88 day rotation period is suggested with high confidence in the light curve data is significant and speaks to this as a possible cause or at least as a contributor to the anomalous light curves.
3) The large-scale anomalies in the Kepler light curves occur very late in the mission with the earliest occurring just shy of 800 days followed by a series of events after 1500 days; these are the events that are under scrutiny and have caused researchers to postulate an “Alien Megastructure” as an explanation. There are early, small-scale events occurring at 120 and 250 days respectively. All of these events are easily explained if one considers the possibility that these events involve large planets with long periods at great distances from the star, planets, possibly with ring structures to explain the small-scale effects embedded in the detail. The fact that we’re observing them late in the Kepler mission simply speaks to the long periods and, hence, the large relative distances from the host star. Kepler’s third law tells us that the period varies as the 3/2 power of the distance (semi-major axis); that we’re observing these events now, at 6 years, 8 months into the mission, simply suggests that we are starting to observe planets with longer periods at greater distances, large Jupiter or super-Jupiter class planets at large distances from the host star, most probably with large ring structures and/or possibly a host of smaller associated moons. As the mission ages, we will continue to observe more and more of these types of events, events that indicate longer orbital periods with greater and greater distances, periods and distances outside the normal mission scope.
Kepler is looking for earth analogs, hence, for planets whose orbits scope in the single-digit year range. That large signals were detected now simply speaks to the respective planets’ large relative sizes and distances from the star. A 20% light curve attenuation would correspond to a planetary radius of 45% that of the host star, a radius that scales with that of a late M class or early K class star! Clearly this isn’t the case. A likely scenario for the 793 and 1520 day events would be a series of Jupiter-class planets whose orbits caused them to transit concurrently, albeit at different distances. The large attenuation in the light curve associated with these events could easily be accounted for in this manner, not from a single large planet but from multiple Jupiter-class or smaller planets transiting concurrently at various distances greater than 5 or 6 AU from the star. The 1540 day event, with the observed symmetry, suggests a super-Jupiter class planet (~200,000 km) either with a large ring structure or a moon whose orbital period is in the 2-day range. For any planet whose orbital period scales with the time Kepler has been on orbit would only manifest now; such planets would be in the 5 – 10 AU distance range from the host star. As well, we wouldn’t have observed any periodicity as yet, since the Kepler space telescope has been on orbit for less than 7 years, not long enough to observe multiple transits of planets with longer relative periods. The mission parameters call for the detection of earth-like planets, hence this observation comes as a surprise.
With power and access comes responsibility. Public policy makers need to be informed by science. Science and society would be much better served if outrageous claims are kept to a minimum and published only if there is substantive evidence to support the claim, evidence that amounts to more than just fanciful hopes and dreams. Without anything more to present as evidence than whimsical notions of a Utopian Galactic Society, it is irresponsible to hold press conferences and publish articles suggesting that an alien civilization and their Dyson sphere/ MegaStructure is the cause for the anomalous light curves of KIC-8462852 or any other star. And we need to tone down the interstellar broadcasts; we need to be very circumspect and careful with what we broadcast. We’ve been “on the air” since the late 1930s and that signal has traversed about 80 light years as of now. We need to be very careful with what we broadcast going forward and this needs to be discussed at the UN level, amongst Heads of State and leaders of all technically advanced nations. The old idiom “Be very careful what you wish for as it may come true” applies in spades here. Once discovered we would no longer be able to hide and the proverbial “cat would be out of the bag”; we would be confronted with a grave reality and a set of problems and consequences no one is prepared to face as we have no way of knowing how an advanced civilization would react to direct contact.
Now that the hoped-for radio signature from KIC-8462852 did not materialize, those who are ambivalent about science and the need for science will have their prejudices confirmed while the rest of us will be left in the same position as before. To suggest that the anomalous light curves of KIC-8462852 were a sign of alien intelligence was a bad idea, even if remotely possible. That headline served no one with the possible exception of certain science publications who are more motivated by sales with hyped-up headlines than real science; it left those of us who fight the good fight for science every day out in the cold and in the same place we were in previously.
Imagination is more important than knowledge
An index of all articles in this blog can be found here.