When I first got interested in SETI, I naively assumed that we would get a detection fairly soon, and that we would detect not a directed beacon but simple background traffic in a remote civilization. I had no idea at the time how difficult it would be to pick up the kind of radio traffic we routinely generate on Earth from a distant star, and as a matter of fact, my interest in shortwave radio led me to assume that, just as I enjoyed the sport of DX — listening for distant signals — so SETI would simply be an offshoot of this, with a harder-to-get QSL card.
Some time in the mid-1980s I wrote a piece called “Where the Real DX Is” for Glenn Hauser’s Review of International Broadcasting, running through a list of the nearest stars and talking about SETI projects that had been tried up to then. I haven’t gone back to read that article in years and would probably find it an embarrassing chore. But it’s interesting to me that the idea of leakage radiation does have its place, particularly in the area of beamed power.
Power Beaming at Work
What I knew little of back in the 80’s was how beamed power — using high-power microwave beams but including millimeter-wave beams and lasers — might empower a space-based infrastructure. While television and radio signals are all but undetectable from another star (at least, for a civilization at our level of development), intense, focused beams to impart power to a spacecraft present a better target. The interesting question that James Benford (Microwave Sciences) and son Dominic (NASA GSFC) ask in the paper we began looking at yesterday is just how detectable power beaming would be.
This takes off on ideas Jim Benford discussed last year in these pages (see Seeing Alien Power Beaming), and both Jim and Dominic recently looked at the question in relation to SETI efforts on a very intriguing star indeed in Quantifying KIC 8462852 Power Beaming. After all, if a distant civilization were building something like a Dyson sphere or ‘swarm’ around a star, it would have to have constructed an infrastructure that might well involve power beaming technologies.
Image: A favorite image from a favorite artist, Rick Sternbach. Here we’re looking at an interstellar lightsail near an exotic world. The uses of beamed power in near and deep space are numerous, and many of them appear to be detectable from a SETI perspective. The image comes from a 1983 issue of Science Digest. Credit: Copyright Rick Sternbach.
The Benford paper runs through a number of beaming concepts ranging from orbit raising, a lower power application, to actual launch to orbit using microwave thermal thrusters. Various high-power beaming applications have been quantified for missions within the Solar System as well, using microwave or laser beams to boost craft to 100 to 200 kilometers per second. A mature infrastructure might involve high-speed unmanned supply craft being decelerated upon arrival by a beam system similar to the one that launched it. I mentioned yesterday that beaming from a solar power station in space to a planetary surface is not a likely observable. Here’s why, whether we’re talking about microwave bands or lasers in the optical range:
The beam must be carefully controlled to deliver power to the receiving rectifying antennas on the ground (Mankins 2014). Any side emissions are economic losses, therefore substantial measures would be taken to reduce side lobes to a minimum. Further, the first several sidelobes are absorbed in the ground. The remaining side lobes are dispersed in angle so that the power density in the far field will be very low. For the worked example in Mankins (Mankins 2014; Dickinson 2016), the back lobe is down 40 dB relative to the ? 1GW main beam.
And note this:
This is in contrast to power beaming transportation applications, in which the varying solid angle of the receiving spacecraft results in the main beam increasingly leaking around the edges of the vehicle being accelerated.
So that takes detection of one of the numerous power beaming scenarios off the table, but many others survive scrutiny. Have a look at this table from the paper, which draws on representative parameters for applications of power beaming presented earlier in the discussion.
Here we’re looking at observables in terms of slew rate (movement of the beam), the EIRP and the observation time. EIRP stands for Effective Isotropic Radiated Power, the measured radiated power in a single direction — it’s the product of the antenna gain times the power radiated. For useful background, the standard text is Jim Benford’s own High Power Microwaves (now in its third edition, CRC Press, 2016). A quick note on EIRP from the paper:
Spectral flux density, typically denoted in Janskys, is the power density divided by the bandwidth. While this is commonly used as the observed quantity in radio astronomy, we cannot know the bandwidth of an ETI transmitter. Consequently, in thinking about ETI power beaming mission [sic] we must deal with EIRP, not spectral flux density. Beaming power does not require or even necessarily benefit from narrow bandwidth; energy transference is what matters.
Ranking the Observables
The possibilities are numerous, and not all of them designed for deep space. Microwave thermal thrusters, for example, can be fed by a high-power microwave beam in a single-stage rocket with a flat aeroshell on the underside covered by microwave-absorbing heat exchangers. The system is efficient because the energy source remains on the ground — see the paper for further parameters on this as well as orbit raising, where ground-based energy sources lift a satellite to a higher orbit. As the table shows, orbit raising is significantly lower in power than launch from the surface.
But of course beaming applications deeper into the system are a part of a robust infrastructure based on beaming, and here we can look at interplanetary transfers by beam-driven sails, as well as starship concepts involving prolonged acceleration of an interstellar vehicle, like the Robert Forward concepts I mentioned yesterday. Given the power requirements for starships, such beams would be detectable with our current technology, but this would also require that the Earth fall within the bandwidth of the power beam.
These questions of detectability depend, of course, upon the level of technology of the civilization trying to make the detection. In our case, we have the interesting story of the star KIC 8462852 to give us some guidance. We have radio observations of this curious star that found no signs of power beaming in about 180 hours of observations. The idea was to look for incidental radiated power — leakage radiation — produced by an advanced civilization. The observations were made using the Allen Telescope Array in the 1-10 GHz range.
Refer back to the table above and the beaming applications there. These are the authors’ conclusions re the KIC 8462852 observations using the Allen Telescope Array:
- The 1 Hz channels could see all the applications, but they are not seen.
- Launch from a planetary surface into orbits is marginally detectable, at the threshold of the Allen Array for the 100 kHz observations, if at the frequencies observed. Orbit raising, which requires lower power, is not detectable.
- Interplanetary transfers by beam-driven sails should be detectable in their observations, but are not seen. This is for both the 1 Hz and for the 100 kHz observations.
- Starships launched by power beams with beamwidths that we happen to fall within (to other solar systems, not our own) would be detectable, but are not seen.
We also learn that the limited observation times and wavelength coverage mean that we have no firm conclusions about the star. More systematic studies, which would include observations at higher radio frequencies, would be called for to come up with a stronger result. I should also mention that an optical SETI attempt was made on KIC 8462852 at the Boquete Optical SETI Observatory in Panama. Given the detection limits of the equipment there and other issues discussed in the paper, none of the power beaming applications in consideration by the Benfords could have been detected at the Boquete site.
The authors’ conclusion:
*As discussed above, the beaming power levels are high and transient and easily dwarf any ETI civilization’s diffuse leakage to space (Sullivan 1978). Power beaming described here is larger than that necessary for beaming systems for communication: EIRP = 1018 W for a 1,000ly-range beacon (Benford, Benford & Benford 2010). SETI programs could explore a different part of parameter space by observations suitable to finding leakage from power beams.
We have no way of knowing whether any civilization exists outside of our own, nor can we know if such a civilization would use power beaming. But the virtues of beamed power for fast transportation within our own Solar System — and for lowering the cost to orbit, as well as raising orbits — give us good reason to continue to explore the use of this technology. In doing so, we should keep in mind that we are producing an observable signal that is well beyond those undetectable “I Love Lucy” episodes that are now 65 light years out. I think the Benfords are right when they argue that detectable radiation is a message in itself, whether or not we ever decide to impose a structured message into the beams that power a future infrastructure.
The paper is Benford & Benford, “Power Beaming Leakage Radiation as a SETI Observable,” submitted to The Astrophysical Journal and available as a preprint.
It occurs to me that finding this sort of beaming would have an immediate practical benefit. It would tell us than a more advanced civilization found this sort of use of long term benefit.
I wads watching a SETI talk where the speaker’s values for the Drake Equatiob resulted in ~20 communicating civilizations, with a lifetime of 10^5 years averaging 32k ly apart. Not much room for a 2 way conversation, so it would seem that their efforts might only be for broadcasting an Encyclopedia Galactica.
I like the beaming detection approach because it doesn’t assume some communication, but rather a pragmatic way to transfer energy from a star to consuming sinks, whether starships or dispersed cities or habitats. It doesn’t assume Dyson Spheres, just enough energy collection to power the civilization at that time, with perhaps some growth rate dependent on demand or resources. Unlike star ships, there is likely to be much more beaming to the various consumers around the star offering more opportunities for detection.
This assumes that beaming technology is a reasonably optimal way to transfer energy and that the civilization is not concerned with detection by predators. It also doesn’t assume civilizations will try to colonize the galaxy, providing an answer to Fermi’s question. Because of the distances between civilizations, I prefer this idea to short burst, optimal energy, signaling that does seem to indicate a desire for 2 way communication.
Since the last half of the Drake Equation still contains a number of unknowns, one can still plug whatever numbers they want into it to get any quantity they want.
Carl Sagan famously demonstrated this in Cosmos, getting anywhere from 1 to 10 to 1 million technological civilizations in the Milky Way galaxy. Your mileage may vary.
http://www.dailymotion.com/video/x271be_carl-sagan-explains-the-drake-equat_tech
I would put it on the high end, since there is a nice marker that is not used in the Drake equation: How many advanced civilizations that live on worlds that their sun is totally eclipse by their moon. We live in a short period of time when the moon (which is slowly moving away from the earth) is at the position where half the solar eclipse are total and half are annular. So how many planets would we have to find to see this happening now?
I see three main choices as to how we look at it:
1.God created it that way.
2.Some civilization was here before and set it up that way.
3.There are so many civilizations out there and some like us have an unusual coincidence that create a total solar eclipse.
Those are the main ideas, but would love to hear other ideas along the same concept.
And why does it matter if the moon eclipses the sun?
Mike Fidler: I’m sorry but I’m not quite following solar eclipse angle, could you elaborate? Is a total eclipse some “driver” or marker of an intelligent species?
There is another “main choice” you should add: (4), “Coincidence”.
If any given planet has a moon orbiting it, it’s highly likely this moon’s orbit will be in the same plane as the planet’s orbit. Most moons (but not Luna!) form in the same accretion disk as the parent planet, thus eclipses are highly probable (but most likely, not total) But I agree: What is anomalous is that Luna’s apparent diameter (which is time dependent) so closely matches Sol’s. Not convinced this is any kind of proof of some ETI “messing around” with it.
The Drake Equation uses a statistical approach to calculate how many civilization exist. The point is that in any 3 body system the time that the planet and its satellite will be in a position to be 50/50 total annular/total solar eclipse will be relatively short, therefore, though there may be many planets that have this Coincidence only a few will have a civilization that can comprehend its significance. Under choice three, the point is how rare this coincidence is, why are we so lucky?
This leaves us with the solution that there must be very many advanced ETI in our galaxy. Of course you can have blind faith and say God created it that way!
So we are the only intelligent civilization that exist in our galaxy and we are just starting to understand and realize that there should be many advanced ETI, so where are they? The earth centered mentality of our species leads us down the road to think we are it. So why are we so lucky to have life develop and evolve on this planet with total solar eclipses that are so rare.
You are correct in saying eclipses are common, just look at the rest of the solar system, but none of these eclipses have that unique ability to just cover the sun. Those are the only examples we can now use to compare the frequency of this occurrence. Hopefully in the not so distant future we will have many other examples to work from when we find exomoons!
It kind of reminds me of Sagan’s book , “Contact” – Pi within Pi.
I am using generalization for the three viewpoints of this idea.
1. A person of faith.
2. A person of new age/UFO.
3. A scientist.
It is more of a philosophical question, some what like the arguments on the wave/particle duality and the uncertainty principle.
There is one other choice!
4. Cosmic Surrealism!
Like the work of M.C. Escher.
A black hole in the sky.
Absolutely number 3.
The dinosaurs never witnessed this coincidence and neither will our far descendants. With a moon formed at an orbital distance of 10000 km around an Earth with a 6 hour day (and huge tides!), tidal forces are still slowing the Earth and migrating the moon outward at 2.5cm per year so this gorgeous display is fleeting but relatively long lived.
Your point 1. is maybe only for Christians and a few similar religions and certainly not for me, and your point 2. is dangerously close to breaking forum rules.
Ah, but in the universe there are no rules just reality!
I like number 4. An artist.
Because that is one thing humans are very good at.
Carl Sagan has a paper somewhere , where , in the Drake equation, he estimated the margin of error for each parameter. (As best he could , at that time.) This gave a cumulative uncertainty for the final number. It was quite large.
Has anyone done this again in recent times?
Whenever I play with Drake’s equation, I feel as though I am driving on a country road at night, faster than my headlights reveal the road. When it comes to the emergence of technological intelligence, deductive reasoning will only illuminate so much of our naivete.
Another way to think of this is what is the maximum distance that a technological species such as ourselves could detect another technological species such as ourselves having the same technology level. It could be less than 100 lyrs in which the galaxy would be heaving in technological species such as ourselves and we would not even notice them. We need more scopes, perhaps we need a megastructure like a large golf ball with radio dishes to scan the expanse, they would be very light and could be made very large.
The problem with this view is that it requires ETI to remain confined to the vicinity of their home star, forever.
Strange. How can someone who knows so much about astronomy be so ignorant about biology. Sagan thinks f(l)=1 because chemicals can self assemble!! To him the minimal non-trivially self-reproducing entity from which it all began should require no more than a bundle of amino acids to collect and fry in one place.
Rob:
I do not agree that Sagan was ignorant about biology. The conclusion that f(l)=1 was arrived at by consensus by Sagan, Drake, Lilly, Struve, Calvin and etc in the 1961 “Drake Equation” meeting. OK, they could have had stronger biologist representation.
Given: Life appeared on Earth surprisingly quickly. Complex life (photosynthesis) fossil evidence exists very soon after life’s appearance. It seems that life got established as soon as it could, i.e: as soon as Earth cooled down enough after formation to allow liquid water. So even though we cant figure out HOW?! yet, this implies that life must be an “easy” thing to do, as nature has figured out how to do it given only a couple hundred million years (which seems to get pushed closer to Earth formation at 4.56 billion years ago every year). Given this evidence, the Drake meeting guys assumed that when life can arise, it does, f(l) is unity.
I think that is a reasonable assumption given the facts. We need to find other life creation events at Europa, Enceladus, Titan, Mars, exo-planet bio-signatures to support this hypothesis.
OR….. The Earth quick life start can also be evidence for panspermia, which was not even a theory in the 1961 meeting.
OR….. It could be evidence for a special (divine?) creation event, which actually WAS discussed in the Drake meeting, but tabled.
Look at the video again. Sagan gives as his main reason for believing f(l)=1, the ease of making biomolecules under cosmic conditions. Its early appearance on Earth was only a secondary consideration. If he tried to make it the primary one – then he would have showed faulty methodology in not mentioning he had assumed that abiogenesis didn’t require conditions that could only predominate early in Earth’s history (such as high levels of methane, or vulcanism)
Admittedly, during the 1950s, and early 60s, when vitalism was still thought to be a valid explanation for life, experimental results, such as those by Urey and Miller, seemed significant. Later than that, and evidence that the simplest life was of a mechanistic von Neumann type was overwhelming. This requires a deeper explanation, and Sagan was giving the equivalent of “I don’t understand it so it must be simple”
We seem to have hit a bit of a Lord Kelvin theme recently. They SHOULD have known of panspermia at that meeting, since Lord Kelvin presented a variant of it, now called lithopanspermia, in 1881. Despite being an expert in heat transfer he was adamant that this need not be a killer problem, yet he was only recently proved correct. In 1920, another version called lithopanspermia, was developed in detail by Arrhenius.
In those times there was much belief in both Darwin’s theory and the Steady State (at least its idea, not necessarily the later detailed model). The idea that life evolves has been around and much used for >>2000 years but Darwin proposed that biology wasn’t teleologically driven, and as such no new biological function could EVER arise except via natural selection over random variation of pre-existing organisms. This provided a massive problem for the origin of life – and panspermia could fix that in a Steady State universe (because, then, it didn’t need a beginning)
I think there is a strong chance we will discover that we are all Martians as Mars, because it is so small, was probably the first of the 3 terrestrials to have favorable conditions for life, i.e: reasonable temperatures with liquid water (given that all 3 planets had harvest-able energy sources and organics as well).
We need to go look around and gather evidence. Can we find a second Genesis in our Solar System? Can we discriminate between separate or “special” creations and panspermia? Or…. Will Fred Hoyle’s ideas be vindicated (life arises in comets and is disseminated throughout the galaxy)? We should also continue to look here on Earth for shadow life and at exo-planets for bio-signatures. My money is on Mars, first life detection, it will be indistinguishable from Earth life. Within 15 years.
Or …perhaps there is something very basic, very easy about life’s creation from simple building blocks that nature knows how to do …but …somehow we have overlooked. For 60 years?
Alex:
No, but it makes a much stronger assumption: That civilizations will never try to colonize nearby stars, despite the availability of high power beam propulsion. If they did, their descendents would eventually have arrived here, and Fermi’s question (“Where are they?”) would remain unanswered.
Good thoughts, Alex.
@Ljk. Indeed. I’m so skeptical about the likelihood of technological life emerging that I come up with less than 1 civilization. So we are it, alone, in this galaxy. :(
Having said that, if there 1 million technological civilizations currently out there, the Fermi question becomes important, as well as our lack of detecting the “galactic club”. If we don’t need to assume some sort of communicating effort, just the stray emanations from a high tech civilization, then the issue of communication goals disappears and we can just look for signs of civilization based on the by products of their technology. Whether the civilization communicates or is fearful of shouting into the dark, stays in its home system or expands to other nearby stars, becomes almost irrelevant.
An interesting parameter would be
lifetime-of-civ / interciv-communication-time
if civs technical lives are 10K on average, but the expected minimum separation of civs is 1K LY, then at best a pair of civs that are 1K LY apart would only be able to have 5 roundtrip communications before one of them dies out. I did a calculation once that if there were 10K cotemporaneous (radio capable) civs in Milky Way, then they’d be on average 1K LY apart. So your *closest* civ would be 1K LY. If you only live (are radio capable) for 10K LY, there’s not going to be a lot of intercommunicating going around. If you’re lucky you could do archaeology on some dead civ’s leakage or intentional signals.
The concept of a “galactic club” completely breaks down in the light of communication delays, as kamal ali observes. We have three possible sitautions here:
1) We are alone
2) There are a number of ETI that arose independently according to the Drake equation, but none of them ever thought of (or succeeded in) colonizing other systems.
3) There is a growing number of ETI that are related to each other by descent. Since our system has not been settled by any ETI, we must be observing this number in the process of growing before the galaxy is filled.
ETI that are related by descent would know of each other, and exchange historical data with each other, but because of the communication delay would not be able to maintain empires (or clubs) across interstellar distances.
4) Expanding into the galaxy does not include settling every system. With such a model, the Fermi Paradox remains relevant but is proportional to our detection technologies.
A rational model for interstellar expansion requires predicting:
the lifespan of individual inhabited systems
the lifespan of the lineage as an aggregate of individual inhabited systems
the economic realities of colonizing systems
how a lineage avoids Malthusian crises
how a lineage evolves, what resource niches will it fill
what is the value to a lineage or individual colony of a system inhabited by an independently emergent, complex life
I think what you describe Harold is AKA the “Percolation Theory”. Not every star in the galaxy gets colonized: it is contingent on the expansion drive and goals (and etc). of the colonies as you have described. So, we could be in a void that has not (yet?) been colonized.
There are no beacons close by, we can rule that out.
And I suggest we need to remind ourselves is this fact: Given our current technology, we would be challenged to detect our own radio leakage from more that a couple light years away. And this leakage drops with every passing year as fiber optics, more efficient ways to transmit and etc. replace broadcast towers and spill-over emissions.
The keyword here is yet. If we are in a void, we are also surrounded. What do you propose would keep the surrounding ETI from colonizing the void, eventually? What could be keeping them out for billions of years?
Eniac:
Because inter-stellar travel by biological entities is extremely difficult or impossible. The galaxy is more likely inhabited by post-biologicals millions of years more advanced than us who may or may not choose to colonize their nearer star systems. AI has no reason or desire to communicate with us backwards meat sacks. Perhaps AI will communicate with each other, it would be broad band/high information rate and very low energy, targeted at each other, but for sure not an easy to spot beacon or leakage. Our solar system may not offer the desired resources for sentient AI. Their requirements (at a guess) are probably lots of energy flux with very easy to extract material resources.
The AI seem very possible. I’ve always thought that we should look for those in very different places than we do for “civilizations”. It seems to me that young hot systems with lots of new small bodies would be the prefered place for these.
I suppose it is possible that our system is lacking resources (energy and raw materials) that other systems have. To the extent that, even after all those other systems are occupied, there would still be no incentive to come here.
I would much love to know what those lacking resources are, though, because I can simply not imagine any. We have sunlight, and lots of rocks flying around. What else would other systems offer that we do not have?
Whether they would be interested in us or not is irrelevant. We were not here, back then, billions of years ago.
Whether the ETI are biological or post-biological is also irrelevant. I made no assumptions on this point. What matters is that they have not come here.
The only undeniable fact is that we have not detected a powerful beacon that is aimed at us. Aside from the “Wow!” signal, maybe.
They could have visited many times before recorded history. They could be silently lurking in the asteroid belt. They could be in the Alpha Centauri system or closer, and we would not be able to detect their leakage.
We need to go look around the Solar System and construct gigantic radio telescopes on the dark side of the moon before we can rule out “No neighbors.”
Fascinating so much work has been done on hypothetical alien (or far-future) technology. Need to dig into this a bit.
For those interested, Tom Ditto has a new SETI talk posted this week about his telescope designs that use diffraction as the primary objective. Exciting potential for exoplanet observations, and in particular for spotting blue planets.
I found this interresting article,
KIC 8462852: Models of transits
http://www.datasciencecentral.com/profiles/blogs/kic-8462852-models-of-transits
But i am not an expert, someone have a comment on this work ?
Yes it is an interesting article.
I am also not an expert in this area – we need the experts to go over these light curves and develop plausible models of what shape(s), size(s) and opacity(ies) could be occulting KIC 8462852.
I think Jose Solorzano is being a bit generous in his assessment that the 792 day occulter could be as simple as a Niven ring. We have a huge imbalance in the ingress and egress and even a tilted object occulting just one hemisphere is unlikely to produce that level of imbalance.
I think we should look for potential leakage of powered beams (from KIC 8462852 and elsewhere) but I am not optimistic that we will find any.
Population trends indicate that we have around 100-200 years to solve the problems of interplanetary and interstellar flight – beamed technology seems to be the best option atm.
After around 2100-2200 falling population and diminishing requirements for energy and resources will likely result in significant problems in any further development of space based industries. I think we have a very small window to either become a space faring species or remain bound to the inner portion of the solar system.
Two experts DID do an EXTENSIVE ANALYSIS a few months ago, and their paper was accepted by what I assume to be OTHER experts in the field. Eva Bodman and Anne Quillan concluded that all of the lightcurves WITH THE EXCEPTION OF THE symetric(IN THEIR OWN WORDS)”Q8″ 15% dip were most likely caused by comets. What they did NOT elucidate on, in the paper, were what other POSSIBLE CAUSES ALSO fit the data. Until Schaeffer’s paper is ACCEPTED, their analysis SHOULD be accepted as the most likely cause, and Schaefer’ s “one cause for ALL of the dimmings should STILL BE HELD IN QUESTION!
Interesting, Kartouch! The model’s best fit assumes a “Niven Ring” and the effect is much more subtle than I had a mental picture of.
General comment, Power beaming: What constrains the beaming frequency? What constrains the beam’s bandwidth? Am I correct that the Earth’s atmosphere is opaque to frequencies above about 100 GHz? Thus if an optimal power beaming frequency is, say 250 GHz (they power beam their craft from orbit) for whatever reason, we would not be able to detect it, correct?
Also, examples are given above of beaming frequencies in the 68 to 100GHz range (I suppose constrained by beaming from an Earth-like atmosphere). The Allen Array looked at Tabby’s Star and did not detect power beam leakage, but the top end of this telescope is stated above as being at 10 GHz, so I do not quite follow the claim of non-detection.
It has been my understanding that the Allen Array in it’s current state of construction is neither sensitive enough, nor covers a wide enough range, to determine anything but an upper bound. It was the first thing available to do a preliminary search while astronomers were booking time on more powerful instruments… these more sensitive surveys are hopefully to be performed in the near future. I love the Allen Array and really had my fingers crossed that it would strike gold right out of the gate but I wasn’t too disappointed at all with the result… it’s just the beginning!
An interesting take(and a so-so video)on this is currently up on http://www.anaincientsolarsystem.com. Large objects like comets and Niven Rings are apparently OUT(although the video shows what appears to be a very DIFFUSE ring-like structure), and the FINAL TWO CANDIDATES appear to be a semi-transparent cloud of some kind(probably NATURAL but UNKNOWN to science) or a VERY ORGANIZED SWARM of very small SOLID OBJECTS(probably NOT natural, and something AKIN to solar-powered nanosats). In both of these cases, WHERE’s the infra-red EXCESS. A cold semi-transparent cloud should take MUCH LONGER than just a few days to transit unless it is MUCH CLOSER TO Earth than to KIC8462852. Solar POWERED sattilites MUST be orbiting close enough to the star in order to be able to FUNCTION. To me, this just muddies the situation EVEN MORE!
Harry Ray: I could not get your ancient solar system link to go (“server not found”).
I hate to sound like a broken record on the non-detection of excess IR…. but here goes. We may assume too quickly that non-detection weakens the ETI and associated Dyson structure hypothesis. It could actually strengthen the hypothesis. Assuming our sensitivity to detect IR from 1500 light years away is up to the task, most or all of this “waste heat” may be getting beamed or re-radiated away from our view. Or it could be radiated at such a low temperature (very high efficiency, with lots of work being extracted before its tossed over board) that we can’t (yet?) detect it, in the neighborhood of <100K. Or it could be a combination of the two.
I think the correct link is: http://ancientsolarsystem.blogspot.com.au/
It basically refers to Jose Solorzano blog at data science central and modelling that implies a Niven ring like structure for the dip at day 792.
This was posted and linked to previously but here it is again if you missed it.
http://www.datasciencecentral.com/profiles/blogs/kic-8462852-models-of-transits?xg_source=activity
“An Answer for you? Yes, I have.”
“There really is one?”.
“There really is one,”
“To Everything? To the great dips in KIC 8462852 light curve?”
“Yes. Though I don’t think, that you’re going to like it.”
“Doesn’t matter! We must know it!”
“You’re really not going to like it,”
:) Nice reference to HHGTTU
Now that we have “Name Exo Worlds” up and running, are we ready for “Name Exo Beings”? Should the INCREDIBLE happen, and KIC8462852 be PROVEN to host ETI, what is the name that we will give them? Several possibilities inclue Tabithians, Boyajians, Tabians(all derived from Tabitha Boyagian), Keplerians(derived frim Kepler), and Brunians(derived from Giordano Bruno., _ites for -ians(for ALL previous entries. MY FAVORITE: KIC8462852 is probably, in the end, going to br designated “The Flux Star”. So Fluxians immediately come to mind(NOT Fluxites). BUT, to REALLY grasp the MEANING OF THIS: Should these ET’s really DO exist, and ALSO be proven to be the PRODUCERS of ALL THE FLUX associated with this star, the best name for them would simply be “The Fluxers”!
Jose Solórzano’s model indicates the following:ONE; an INGRESS of just under SIX DAYS, TWO; a FULL TRANSIT of just over ONE DAY, THREE: an EGRESS of just under THREE DAYS, implying an ingress/egress RATIO of ALMOST EXACTLY 2/1! If you remember, my estimates were in the 2.3/1 to 2.4/1 range. I cede to him, because he is much more of an expert than I am. What I am leading up to here is INCREDIBLY IMPORTANT!! Whatever transited KIC8462852 in the “Q8” ten day(including ingress and egress) period MUST HAVE CHANGED ITS SHAPE CONSIDERABLY in just those ten days to produce the DIFFERENCE in the ingress and egress! I do not see how a semi-transparent cloud could do this in JUST TEN DAYS. Umpety Zillion solar powered nanosats could do it if their ORBITAL CONFIGURATIONS were such that the LEADING EDGE of the ingress nanosats were in a slightly longer orbital period than the trailing edge. Then, seven days later, the trailing edge STARTS TO CATCH UP with the leading edge, to produce an egress of a CONSIDERABLY SHORTER TIME PERIOD! Because the TRUE RATIO COULD BE 2/1, this configuration COULD BE DELIBREATE, implying a MESSAGE BEING SENT!!!
Harry: Couldn’t you get the same 2 to 1-ish transit signature from something with an overall tear-drop shape? The pointy end of the drop on the ingress side. A shape that does not morph as it transit’s. A “soft” signature. A swarm of somethings that are not required to change the overall shape of the mass during the transit.
If you want to mentally exaggerate and “sharpen” this tear drop transit signature, imagine a triangle transiting with the pointy end on the ingress side.
It could, but ONLY if the transit started at the equatorial region where the curvature of the star is at its LOWEST, and ended at or near the polar region where the curvature of the star is at or near its GREATIST. I am no expert in orbital dynamics, but logic dictates this to be a QUESTIONAL configuration at BEST. ALSO: My terminology in the above comment was imperfect. When I implied “ingress” and “egress”. I really meant “HORIZONTAL ingress” and “HORIZONTAL egress”. There is ALSO a VERTICAL ingress and egress if(AND ONLY IF)the transiting object is a RING- LIKE structure in a polar orbit but ALSO changing it’s configuration via precession or libration, as the video IMPLIES! The one day “total transit” I implied is actually only a HORIZONTAL “total transit”, and VERTICAL ingress and egress ONLY are occurring at this time period.
The main tangible conclusion here is that the extent and smoothness of the light curve appear to exclude opaque objects. Like so:
This, for me, clearly points to the comet hypothesis. Also, despite what has been claimed, there aren’t really any convincing arguments refuting the comet scenario as laid out by Bodman & Quillen (http://arxiv.org/pdf/1511.08821v1.pdf).
I think we have to accept the boring thing that this looks like, not the grandiose thing that we hope it could be.
I think the jury is still out on the comet hypothesis.
A small group of comets could separately explain the early Kepler observations, but these would not explain the later dips.
A contrived model could come close to explaining most (BUT not all) of the dips around 1500-1570.
I quote from the Bodman and Quillen paper:
“We do not attempt to fit the first large dip at day 800 as its shape, a gradual decrease in flux followed by a sharp increase, is the opposite of a typical comet transit light curve and not well explained by a simple model. We assume this earlier dip is unrelated to series of dips that are our focus.”
Clearly the dip at 792 cannot be explained by the comet hypothesis and the early dips do not fit with this swarm of giant comets that could explain MOST of the 1500-1570 dips.
To get anything close to the observed light curves at 1500-1570 we need between 73 giant comets (100km) and 731 large comets (10km).
Although a swarm of giant comets is not impossible, I think other explanations such as a brown dwarf with a large complex planetary/ring/dust system at significant separation from KIC8462852 could equally explain the observed dips around 1500-1570.
Bodman and Quillen have shown that some (but not all) of the dips observed by Kepler could be explained by a swarm of giant comets.
However, we need to explain the ENTIRE light curve for KIC8462852 and as yet no explanation, natural or constructed, has satisfactorily done so.
IF Schaefer is correct (even in part) that there is a longer pattern of variation in the light curve for KIC8462852 then this would also need to be included in the resultant model/hypothesis.
Eniac said: “Also, despite what has been claimed, there aren’t really any convincing arguments refuting the comet scenario as laid out by Bodman & Quillen”
I won’t go into the details of the whole light curve and the problems with the comet explanation but here is one clear example (not sure if it is a “convincing argument”).
I would suggest that the dip observed at 1540 is extremely unlikely to be caused by a swarm of comets.
The 1540 dip (Dip 9) is completely symmetrical in terms of timing. The majority of the large central dip is almost perfectly symmetrical and the timing of the dips before and after are also almost perfectly symmetrical.
The overall timing of the beginning of the ingress and finish of the egress (at around .999 flux) are also almost perfectly symmetrical.
If this light curve was seen around any other star the explanation would be that we are observing a large planet/brown dwarf and ring/dust system – there are similar light curves observed for other stars (eg J1407b).
To construct the same effects (timings, symmetries, smoothness of the central dip etc) using a swarm of comets, although not impossible, would be extremely difficult.
I do not understand why we would choose a highly contrived explanation for the dip at 1540 when there are far simpler explanations.
10 kilometer to 100 kilometer comets ARE VERY OPAQUE OBJECTS, and produce HERKY- JERKY lightcurves like the 80 day period lightcurves at the END of the four year Kepler observation period. Remember, Bodman and Quillon AVOIDED the “Q8” light curve as if it were the plague! Jason Wright even commented on this in one of his tweets JUST AFTER their paper came out!
THERE IS ONE NOW! Log onto http://www.science2.0.com, scroll down to “blogs” Jose Solarzano’s “The real reason why the KIC8462852 comet hypothesis is dead”. He RE-ITERATED(almost EXACTLY IN MY OWN WORDS from previous comments) my position on the “Q8” light curve. I took the liberty to do some “science” using the illustration on this blog and found out that the ingress-maxima ratio is ALMOST EXACTLY one to one! I stated in a PREVIOUS comment that the ingress-egress ratio is almost exactly two to one. WHAT ARE THE ODDS ON BOTH OF THESE RATIOS being integers with comets? I don’t want to start sounding like the “Ancient Aliens” crowd, so I will draw absolutely no conclusions as to WHAT THIS COULD MEAN, but you better believe that THEY will!!!!
Your link is invalid. : (
Here the correct url. :D
http://www.science20.com/indepth_analytics/blog/the_real_reason_why_the_kic_8462852_comet_hypothesis_is_dead-167340
Interresting !
At the link you cite he comes to the conclusion that:
So, maybe that is what it is, then. Maybe it is a single, large comet outgassing a large swarm of debris or dust.
In any case, Solorzano makes good points, but nowhere in the text does he actually explain why “the comet hypothesis is dead”, as the title claims. That conclusion seems to be just as much an unsubstantiated leap as Schafer’s.
To me, the comet hypothesis is alive and well. It is certainly the least contrived of all proposed explanations.
If you have a planet with its aphelion towards us the transit time is a lot longer if the eccentricity is high, transit times are measured in days as we see here.
If you use M=1.43 and an orbital period of say 25 days (~big dips) using this interactive you get a semi-major axis distance of ~28 million km
from http://orbitsimulator.com/formulas/sma.html
and use http://orbitsimulator.com/formulas/velocity.html
you get quite a low transit velocity at aphelion which equates to a longer time of dimming of many days.
opps forgot to say with a high eccentricity!
No planet is large enough to cause these kinds of dips. It has to be an extended cloud, like those that comets like to form when they are outgassing.
If it has an semi-major axis of ~28 million km’s it will have a high temperature already, if it has high eccentricity it will get even hotter closer in. I feel the planet has a ring/cloud system driven by this intense heat of close approach, the planet may have a low mass that allows easy escape of gases from it atmosphere. There is also the potential of moons causing or altering the cloud of debris to give the strange pattern we see.
Michael:
Does a close-in orbit and extremely hot exoplanet, hypothesized to be surrounded by a evaporative cloud (that must be many multiples of the diameter of our own Jupiter to render 20% dimming), explain the lack of detectable excess IR? Would we not expect to see a periodicity in the dimming events at multiples of some suggested orbit? Given that Tabby’s star is tilted at about a 65 degree angle to our line of sight, not sure if this helps bolster your hypothesis or not… If this suggested exo-planet is evaporating (and thus is a transient event) we are lucky to observe it now because in a few million years (or less?) it will totally disperse. That seems implausible.
‘Does a close-in orbit and extremely hot exoplanet, hypothesized to be surrounded by a evaporative cloud (that must be many multiples of the diameter of our own Jupiter to render 20% dimming), explain the lack of detectable excess IR?’
There are examples where evaporating planets have similar spectroscopy profiles (excess Sodium D and Calcium) and Planet HD 209458b, for example (see light curve animation), has short but deep dimming events ~20%. If this planet/moon was flash fried close in and then went to aphelion (our line of sight) where it is moves slower across the disc it would give the day long deep dimming events. If water is broken down and there is no recombination in space there should be no excess infrared but dips in UV parts of the spectrum indicating hydrogen and hydroxyl ions. Due to the distorted light curve to me it looks like moons may be altering the profile of the material. I tried to get some spectro images from NOT but no luck.
http://vega.lpl.arizona.edu/~gilda/extrass.html
WASP 12
http://arxiv.org/pdf/1303.3375v1.pdf
‘Would we not expect to see a periodicity in the dimming events at multiples of some suggested orbit? Given that Tabby’s star is tilted at about a 65 degree angle to our line of sight, not sure if this helps bolster your hypothesis or not…’
I am looking at the collection of dips to see a period of around 22 to 25 days between groups of dips. I also feel it may be bullied by another planet that alters the orbit period, it also looks like gravity darkening is playing a part.
‘If this suggested exo-planet is evaporating (and thus is a transient event) we are lucky to observe it now because in a few million years (or less?) it will totally disperse. That seems implausible.’
Planets can take billions of years to evaporate.
What data would confirm this hypothesis? Spectral showing sodium and/or calcium during a dimming event?
I would expect during a dimming an increase in dips in both sodium and calcium but more importantly increased dips in the hydrogen and hydroxyl part of the light spectrum which would indicate water. I have asked for the spectroscopy info again from NOT.
Michael:
Do you see a 20-ish day periodicity? If so, can you post a plot showing this or give us a handful of the days of the period so we can try and tease it out?
You stated that “…Planet HD 209458b, for example (see light curve animation), has short but deep dimming events ~20%. If this planet/moon was flash fried close in and then went to aphelion (our line of sight) where it is moves slower across the disc it would give the day long deep dimming events.”
BUT the two deep events for Tabby’s are not a day long or even two or three, they are closer to a week and a week and a half, the 1500 day event is especially pronounced. Something that takes this long to transit would be about in Uranus’ orbit, with a period of 100 years-ish, or at least it’s aphelion.
I have used this data set,
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/ICETimeSeriesViewer/nph-ICEtimeseriesviewer?inventory_mode=id_single&idtype=source&id=8462852&dataset=Kepler
On the quite periods there is the usual 0.9 d period and there appears to be another one of 21 days in this set below and there are others in the other quarters.
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/Pgram/nph-pgram?file=%2Fwork%2F%2FTMP_dJbKca_24118%2FICETimeSeriesViewer%2F24118%2F%2Finput%2Fsources%2Fkplr008462852-2012004120508_llc_lc.tbl&xcol=TIME&ycol=PDCSAP_FLUX&title=8462852&origin=Exoplanet%20Archive%20-%20Kepler
If you look at each Quarter you will see dips and you can calculate the periods with the Periodogram component. Looking at it in greater depth it appears random but there are planets with timing variations and relativistic ones as well. Most dips are less than a week.
If this ‘planet’ has moons which are erupting it could have a disruptive effect on the timings as the moons velocities and positions will need to be taken into account. Triton around Neptune for example has an orbit period of ~5 days.
Thank you for the links, Michael.
I agree, it does look like there is something with a period of about 21 days, very surprising to hear about it here at Centauri Dreams first and NOT in a published paper….
I’m sorry ahead of time but I am just full of questions today: Does anyone else see an overall downward trend in flux over the whole 1700 days? Is that some type of data artifact? Assuming it’s valid…. Can this dimming be explained away by something to do with Kepler’s orbit? Or Kepler detectors/electronics aging? An intervening dust cloud thickening? Sol’s or Tabby’s Zodiacal dust? Tabby’s Star moving way from us? Or is it really getting dimmer? Why did Bradley Schaefer not see this?
Can anyone explain the (about 8) step changes in flux? For example, the first step increase occurs between day 349 and 353. Something to do with Kepler’s orbit and orientation toward Tabby’s? Kepler Passing behind our sun?
We must be careful with the period generator as it can misinterpret oscillations, for instance if the object had a ring structure it could see it as three variations instead of been associated with one.
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/ICETimeSeriesViewer/nph-ICEtimeseriesviewer?inventory_mode=id_single&idtype=source&id=8462852&dataset=Kepler
I probably misread the flux on the vertical axis. Either way, Tabby’s flux is not constant over the 1700 days…. or is this a Kepler data artifact? Are the step changes in flux also artifacts?
It would almost be abominable to think as Steven Hawking’s warning:” If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans,” where if there are aliens on tabby’s star building mega strucrures, are acting like native americans building a bond fire around their home star with snowden encription smoke signals, so they won’t get attacted by space aliens. – As Edward Snowden quotes: “Once a society reaches the phase where it starts protecting and encrypting its messages, then messages sent out into space would be indistinguishable from microwave background radiation.”
We are possibly viewing space aliens building a dyson star when emperor justinian was trying to re-conqueror italy from the goths in the year 550.
The idea that spaceships will some day be powered by microwaves reveals, in my view, just how little we know about the universe we inhabit. As scientists once calculated the amount of coal being burned by the sun, the idea extrapolates valiantly an existing knowledge base that is woeful at best.
At the same time I’ve no doubt that interstellar travel will come. Detection of gravitational waves possibly has shown a peek at the science making this happen. A peek, and no more.
And lest we admire ourselves too much, remember that great gobs of the universe are collectively termed ‘dark’. Our trivial baryonic existence has only a taste of the true universal reality.
Moreover, unless it is in fact sure that at the basest levels tiny vibrating strings create existence, no serious advances in understanding our universal environment have been made in many decades.
On the other hand, the Benfords are doing what scientists have always done- making what they can with the tools at hand, and doing so in admirable ways.
I have heard this coal story repeated many times, but cannot find a basis to it. I can verify that astronomers thought gravitational collapse powered the sun before nuclear energy was discovered, but the only ‘coal’ accounts I find come from nineteenth century biologists trying to estimate how much time Earth-life had to evolve. Unless they were polymaths this would make these armature speculations. I could be wrong though, and if anyone knows otherwise I would love a reference.
I can’t give you an original source but I can report from when I was a kid textbooks told this story. Probably has something to do with what “Scientist” means. Same problem sometimes today.
Rob, the closest I can find was Lord Kelvin dismissing the Suns power comes from chemical energy (and he uses ‘coal’ as the example of the then current best fuel).
I google-d “lord kelvin sun coal” and the first link brought up this…
http://zapatopi.net/kelvin/papers/on_the_age_of_the_suns_heat.html
I too have often heard the ‘coal hypothesis’ but have always been of the mind that this idea was quoted to show how it could never be coal and that it showed us we were ignorant of the true source of power.
Thanks for the interesting link. As you say, he does give it, but only in the context of why chemical energy is inadequate. Also notable is that he gives no reference to any scientist who once thought chemical energy was enough.
People did once talk about a burning ball in the sky. What else could it have been other than chemical combustion? Lord kelvin’s proposal was interesting as it used another mechanism, one that would generate energy for much longer. At the time, the idea that the world was created by God less than 10,000 years ago was still in conflict (as it is today in the US *sigh*) with the idea that geology and evolution needed much more time to work if the observations of the rocks and fossils provided a different picture. His initial estimate of the Earth’s age came barely 5 years after Darwin’s “Origin of Species” was published and which was to create a long lasting debate.
At this time, many thought that the Earth was <<1000,000 years old, but this didn't mean that they all followed the biblical chronology.
Lord Kelvin wasn't giving a mechanism that could last much longer, merely further elaborating on the details of a mechanism that was already a known possibility. He states "…the meteoric theory, which appears to have been first proposed in a definite form by Mayer, and afterward independently by Waterston". Note that even Mayer's isn't a mechanism needed to explain the source of the Sun's energy – gravitational collapse is sufficient for that – he is just modifying it by repeated meteorite impacts to prevent cooling and surface area contraction. Kelvin presents a further modification that allows him to explain why these effects could, in principle, be low enough to have avoided detection as at publication.
The only beef I have EVER had with possible ET’s at KIC8462852 is the long-term habitability of ANY planet in ANY orbital configuration around the star! K3V’s are NO G2V’s(correct me if I am wrong Andrew Lepage or other expert reader experts on this subject), and thus NO planet to orbit beaming should occur AT ALL EVER! Where planet to orbit beaming COULD occur is on a long-term habitable planet orbiting KIC8462852’s putative M star companion, but ONLY if the star is SIGNIFIGANTLY OLDER thai KIC8462852, and ALL OF IT’S FLARING HAS STOPPED! What I am completely in the dark about is whether the M star was ALSO in the field of view when the ATA observed KIC8462852(can anybody help me out here?). If the putative ET’S evolved on a planet around the M star, and then manouvered their star into a wide orbit around KIC8462852, colonized an asteroid belt or Kuiper belt, and THEN started their “megastructure project”, orbit rising(OR FALLING) would most likely BE going on, but would need more powerful scopes to detect them. I hope advanced Green Bank, LOFAR, and JVLA are up to the task!
Hi Harry,
I think you meant to say F3V’s are NO G2V’s.
If KIC8462852 was a K3V we would be having entirely different conversations.
What if the M star is slowly drifting (unbound) near KIC8462852?
In that scenario we can have stars with vastly different ages and the M star may be billions of years older than KIC8462852.
In 1.4 million years we should have a similar encounter when GL710 comes to around 1 light year from the Sun.
Has anyone been able to establish the age of the M star near KIC8462852?
If it is still flaring we should be able to observe it.
Yes, I DID mean F3V! I asked the SAME QUESTION about the age of the M star, and Massimo Morengo replied that it has Not been determined yet, and; because it is so far away, and so close to KIC8462852, that it would be very difficult to determine at the present time. As I have stated MANY TIMES BEFORE, when the Gaia data becomes available in JUST A FEW SHORT MONTHS, many of these questions should be answered DEFINITAVELY, the most important being whether the M star is or is NOT in orbit around KIC8462852!
Harry, this is just a guess until we have more info, but I would suspect that with the M dwarf being “so close” to Tabbys* it would likely be in the field-of-view of the ATA.
Having now checked, the ATA fov is about 2.5 degrees… this is a wide fov indeed (the full Moon subtends about 0.5 degree).
http://www.space.com/2056-sharing-allen-telescope-array.html
The ATA has several fields of view, depending on the frequency… even it’s ‘narrow’ beams are 10×3 arcminute ovals. The M dwarf is mentioned often (and here on CD) as 885 au… I would guesstimate that seperation subtends arcseconds to milliarcseconds at 1400 ly distance.
I’m wondering if this analysis was applied to the famous “WOW!” signal. Does it have the hallmarks of being a beamed power event?
@Ron, I don’t believe we gathered enough data from it while it was shining.
BTW, new idea for SETI: sticking to our “transit zone”.
http://www.astronomy.com/news/2016/03/searching-for-aliens-who-already-know-were-here
Is KIC8462852 in our transit zone?
Could Fast Radio Bursts or Gamma-Ray Bursts be Alien Communication Systems ?
Non-random structures in universal compression and the Fermi paradox.
Interesting article: http://arxiv.org/pdf/1603.00048v1.pdf
We study the hypothesis of information panspermia assigned recently among possible solutions of the Fermi paradox (“where are the aliens?”). It suggests that the expenses of alien signaling can be significantly reduced, if their messages contain compressed information. To this end we consider universal compression and decoding mechanisms (e.g. the Lempel-Ziv-Welch algorithm) that can reveal non-random structures in compressed bit strings. The efficiency of Kolmogorov stochasticity parameter for detection of non-randomness is illustrated, along with the Zipf’s law. The universality of these methods, i.e. independence on data details, can be principal in searching for intelligent messages.
Check out Jill Tartar’s “quote” in one of my comments in the MOST RECENT “FRB” POSTING on this website.
Mike, I’m certainly open to that possibility. One thing we know about ETCs is that we don’t know the first thing about them. So who’s to say somebody wouldn’t chew up the energy in a star just to send a signal across the galaxy?
It seems the star is still having significant changes in magnitude.
https://www.aavso.org/apps/webobs/results/?star=KIC+8462852
How is that possible without detection in real time. I thought hundreds of amateurs throughout the world were monitoring it 24/7 for just such a dip.
Very interesting INDEED! At the START of the run, KIC88462852 appears to be CONSIDERABLY BRIGHTER than the value given in the Boyajian et al paper. Then, AT THE END, it trends TOWARD that value! Between Jan 10.72203 and Feb 13.52784, KIC8462852 dimmed by 0.722 The BIGGEST DIMMING between CONSECUTIVE observations was 1.201 magnitudes(between Jan 10.72850 and Jan 15.79132. The BIGGEST BRIGHTENING between CONSECUTIVE observations was 0.505 magnitudes(between Jan 15.79672 and Jan 15.79833)which was 0.00161 days! WOW!!
15,581 observations have been taken by 54 observers, so although not super accurate as a real time curve it is better than nothing.
There appears to be a major drop around 31 Oct 2015
https://www.aavso.org/lcg/plot?auid=000-BLS-628&starname=KIC+8462852&lastdays=200&start=2457316.29626&stop=2457388.37051&obscode=&obscode_symbol=2&obstotals=yes&calendar=calendar&forcetics=&grid=on&uband=on&bband=on&v=on&pointsize=1&width=800&height=450&mag1=&mag2=&mean=&vmean=
Can someone explain what “V Prevalidated” and “V Prevalidated” on the above graph means to a layman like me? I understand that these amateur variable star observers were to inform other astronomers at larger scopes (spectroscopy, etc) that a dimming took place, so does anybody know, did they?
I have pinged off an e-mail regarding if someone else looked at the dip.
Pre-validation means it has only been checked for typos and data input errors only. The photometric system has V as visual and B as blue filters.
Thanks Michael, I also sent AAVSO an e-mail/comment asking if they’ve made the larger scopes aware of the variablity. I see a lot of scatter in the plot but not sure I see a trend. I wonder what a luminosity plot of a typical F3V middle aged star looks like when observed daily, by multiple observers around the world, as Tabby’s is? Would we expect this trend to be flat? Plus or minus 10% error bars? As a control, it would make sense that someone also observe the 2 to 5 “calibration” stars around Tabby’s at the same time (the steady stars that Schaefer and Hippke refer to).
Ooops, “V Prevalidated” and “B Prevalidated” is what I meant
I ASSUME that “V” stands for violet(filter?)and that “B” stands for blue(filter?)
What about this model ? Can it explain the light curve ?
http://imgur.com/a/6335i
The Boyajian et al paper CLEARLY STATED that the RADIAL VELOCITY search for this star found ABSOLUTELY NO INDICATION that KIC8462852 was binary in nature, LET ALONE AN ECLIPSING BINARY! The fact that a light curve can be created using a matching filter using using ALL POSSIBLE ORBITS for eclipsing binary stars that WOULD match the KIC8462852 light curves is not PROOF IN AND OF ITSELF that it would actually BE an eclipsing binary!
Bear with me here, is it possible we have two ringed planets sharing the same orbit, each in the LaGrange’s point?
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/ICETimeSeriesViewer/nph-ICEtimeseriesviewer?inventory_mode=id_single&idtype=source&id=8462852&dataset=Kepler
If you look at this quarter and we look at the large feature between day 1510-1520 and we zone in on the middle peak, a ‘planet’, its peak is at 1517, the two close features either side are say rings-moons. Now the time to the next similar peak later which is on 1567 day, that is ~49-50 days. Now look at the feature that is symmetrical to the right of the large feature, from its peak to its peak the time is ~ 24-25 days. If we look at the last feature in the quarter it looks awfully similar to the symmetrical feature just cut off. Now if you see the times between the similar features peaks they are the same ~49-50 days. So we could have a ~49-50 day shared orbit with the other planet trailing 24-25 days behind, in the LaGrange’s points.
Both planets would have to have EXTREMELY LOW MASSES for this model to work, because otherwise the gravity of one planet would perturb the rings of the other, rendering both ring systems UNSTABLE! Even if this is the case for the 1500 day light curves, it does NOT explain the 792 day light curve. As Schaefer stated in his paper, Occam’s Razor suggests that TWO DIFFERENT SCENARIOS that are BOTH previously unknown to science are VERY HIGHLY UNLIKELY!
Plus, no supporting data for massive planet(s), LaGrange or otherwise, from radial velocity observations, but does not rule out a very long period.
If the ‘planets’ are in L3 positions they would be quite stable and if in a normal circular orbit there would be little radially velocity changes, any movement would be down to mass difference.
I suppose it all boils down to our radial velocity detection sensitivity.
It also seems that 2 or more planets sharing the same orbit (unless they were 180 degrees out to cancel RV-an alignment which is not stable), lets say we have 3 planets at 60 degrees apart? The combined center of gravity would be seen by RV as a single mass and still noticeably affect Tabby’s (assuming we have the required RV detection sensitivity).
If you add ~48.35 days multiple times to 791 the first big dip you hit 1517 and 1566 big dips, look at the centre peaks. The other symmetrical features peak is around ~24 days from the 1517 event and the other cut off feature ~24 days from the 1549 day event. Looks like two objects but maybe it is one which has had a change in period before the 1566 day big dip event.
Just to add, the other distorted feature on day ~1494 is about ~48 days from the 1540 symmetrical event, its peak is just missing, ring-moon distortion maybe.
If I use a 24.175 day period I pretty much hit all the major dips, looks like one planet but may be forced into a timing variation on some dips. Need to look a little deeper as another planet could be bullying it.
http://exoplanetarchive.ipac.caltech.edu/cgi-bin/ICETimeSeriesViewer/nph-ICEtimeseriesviewer?inventory_mode=id_single&idtype=source&id=8462852&dataset=Kepler
WOW! WHAT AN INTERESTING GRAPH, but what the heck does PDCSAP_FLUX[e-/s] stand for. I hope I am interpreting this correctly, but it apparently STARTS at 2.65 and ENDS at 2.5. Take away ALL of the MAJOR dips/dimmings(i.e teal-dimming, brown-dimming, blue-dip, azure-dimming, yellow-dimming, green-dip)and there appears to be a Trend of OVERALL LONG-TERM DIMMING(i.e. red, black, beige, grey, violet, aquamarine, magenta, blush, and red AGAIN)in the four year time period CONSISTANT with Schaefer’s MUCH LONGER time period! Correct me if I am wrong.
Harry, It appears to be a data artifact from Kepler, if you go the website and plug in some other star (KIC 7180968, 1001063, 11498538, 12453925) and ask to plot it’s light curve, they all have the long term downward trend and scatter.
Here’s the website link:
http://exoplanetarchive.ipac.caltech.edu/applications/ETSS/Kepler_index.html
It explains it in here,
https://archive.stsci.edu/kepler/manuals/archive_manual.pdf
‘PDCSAP_FLUX [32-bit floating point] – The flux contained in the optimal aperture in electrons per second after the PDC module has applied its detrending algorithm to the PA light curve. To better understand how PDC manipulated the light curve, read Section 2.3.1.1 and see the PDCSAPFL keyword in the header.’