Dysonian SETI operates under the assumption that our search for extraterrestrial civilizations should not stop with radio waves and laser communications. A sufficiently advanced civilization might be visible to us without ever intending to establish a dialogue, observed through its activities around its parent star or within its galaxy. Find an anomalous object difficult to explain through conventional causes and you have a candidate for much closer examination.
Is KIC 8462852 such a star? Writing for The Atlantic, Ross Andersen took a look at the possibilities yesterday (see The Most Mysterious Star in Our Galaxy), noting that this F3-class star puts out a light curve indicating not a planetary transit or two, but a disk of debris. That wouldn’t be cause for particular interest, as we’ve found numerous debris disks around young stars, but by at least one standard KIC 8462852 doesn’t appear to be young. In a paper on this work, Tabetha Boyajian, a Yale University postdoc, and colleagues see it as a main sequence star with no kinematic indication that it belongs to the population of young disk stars.
The age of a star can be a hard thing to calculate, and unfortunately, at 1480 light years, this one is too far away for us to measure its rotation period or gauge its chromospheric activity. [Addendum: My mistake: Jason Wright just pointed out that we do have data on rotation period and chromospheric activity — the problem is that these are not good age indicators for F-class stars].
But the authors also find that there is no excess emission at mid-infrared wavelengths of the kind we would expect from a dusty disk. That makes for an object unusual enough to have caught the eye of a Dysonian SETI specialist like Jason Wright (Penn State), who told Andersen “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.” Working on a paper of his own, Wright and his co-authors find the star’s light pattern not inconsistent with a swarm of large structures.
One of the classic Dysonian SETI scenarios would be the discovery of a Dyson sphere, an artificial construction built around the parent star to harvest the maximum energy possible. Such a sphere, although frequently depicted in fiction as a solid object, would more likely exist as a swarm of orbiting objects, and as we imagine these things, a light signature like KIC 8462852’s could be the result. That makes the search for alternative explanations all the more interesting, as we try to understand what natural causes might explain the KIC 8462852 light curve.
Image: This view of Comet Halley’s nucleus was obtained by the Halley Multicolour Camera (HMC) on board the Giotto spacecraft, as it passed within 600 km of the comet nucleus on 13 March 1986. The recent paper on KIC 8462852 discusses a cometary influx as a possible cause of the unusual light curves. Credit: ESO.
We’re fortunate to have four full years of Kepler data on this target, allowing the authors to explore a range of possibilities. A large-scale impact within the system is the first thing that comes to my mind. On that score, think of something on the scale of the event that caused our own Moon to form. The problem here is the time frame. The collision would have had to occur between observations from the WISE observatory and a large dip in flux (nearly 15%) seen in later Kepler observations, because we would expect such an event to trigger a strong infrared excess that was not seen by WISE. Such an excess could be there now, but this would also mean that we chanced upon an impact that occurred within a window of just a few years.
Coincidences happen, so we can’t rule that out. The paper also considers catastrophic collisions in this star’s analogue to our asteroid belt, as well as the possibility that we are seeing the passage of a disintegrating comet through the system. In this scenario, the comet would have passed well within one AU. Add in a few other factors and it might work:
The temperatures of comets at such close proximity to the star (> 410 K) would render them susceptible to thermal stresses. The existence of multiple super-Earth planets orbiting < 1 AU from many main sequence stars also points to the possibility that the comet could have been tidally disrupted in a close encounter with one such planet. It is even possible that the comet came close enough to the star for tidal disruption in the absence of other considerations; e.g., a comet similar to Halley's comet would fall apart by tidal forces on approach to within 3-7 stellar radii (0.02 - 0.05 AU).
And this:
Also, since fragments of the comet family would all have very similar orbits, this mitigates the problem noted in Section 4.4.2 that the detection of multiple transits may require orders of magnitude more clumps to be present in the system. Instead a single orbit is the progenitor of the observed clumps, and that orbit happens to be preferentially aligned for its transit detection. That is, it is not excluded that we have observed all the clumps present in the system.
But can the comet scenario explain details in the light curves of KIC 8462852? The paper notes how much remains to be explored, but concludes that a cometary explanation is the most consistent with the data. Conceivably a field star might have made its way through this system, triggering instabilities in KIC 8462852’s analogue to the Oort Cloud. There is in fact a small nearby star that whether bound to the system or not could be implicated in cometary infall.
So what’s next? Andersen tells us that Boyajian is now working with Jason Wright and Andrew Siemion (UC-Berkeley) on a proposal to study KIC 8462852 at radio frequencies that could implicate the workings of a technological civilization. That could lead to further work at the Very Large Array in New Mexico. All of this is as it should be: The appropriate response to a stellar anomaly is to study it more closely while working through a range of possibilities that might explain it. The fact that we don’t see a light curve like this among any of Kepler’s other 156,000 stars is telling. Whatever is going on here is rare enough to merit serious follow-up.
The paper is Boyajian et al., “Planet Hunters X. KIC 8462852 – Where’s the flux?” submitted to Monthly Notices of the Royal Astronomical Society (preprint).
Any thoughts on the required size of the object(s) to generate the dips in the light curve? From what I saw in the paper the dips looked pretty extreme (indicative of solidness? size?). But that could have been exaggerated for detail.
I think it all boils down to the ORBITAL PERIOD of the objects orbiting a rather HOT star. The paper gave no INNER OR OUTER LIMITS! The CLOSER these objects COULD orbit the star, the LESS LIKELY they are to be comets! My best guess is this will be how 49 Ceti will look like when it reaches KIC8462852’s age. RIGHT NOW, 49 CETI has two discs where it is estimated that there is a comet-comet IMPACT every 10 seconds or so(remember back in 2002, 49 Ceti was dubbed “the strangest star in the galaxy” until the mechanism for its disk replenishment was figured out?). Eventually 49 Ceti will only have a FEW PATCHES of comet swarms left in EACH DISK, which, to a KEPLER telescope in the far distant future, would probably look a lot like what KIC8462852 looks like today!
I wonder if we can learn anything on this intriguing star system from what we know about Epsilon Aurigae:
http://www.citizensky.org/content/star-our-project
And since we are discussing celestial objects that appear to be behaving contrary to current astronomical norms, we should be checking out NGC 5907, a spiral galaxy that seems to have a lot more red dwarfs than a galaxy of its class should:
http://messier.seds.org/xtra/ngc/n5907.html
My tentative interpretation of the deep dips (top two events occluding 15% and 22% of starlight) is that these objects are far enough from the star. If you imagine that these transits are produced by debris and asteroids orbiting very far from the star, the relative angular size of the star becomes smaller compared to the top clump sizes, which makes transit that hide a bigger fraction of the star with smaller clumps more likely.
Most of the debris disks that we’ve captured in the past edge-on that still produce transits are close enough to the star to produce lot of IR signature. The lack of mid-IR signature on KIC 8462852 suggests that these objects are orbiting very far from the star, probably exceeding 100 AU. This also explains why we haven’t seen other stars with the same irregular transit patterns, since edge-ons of disks orbiting farther from the star are geometrically less likely
This emphasizes the need to improve our imaging capability in the THz region of the spectrum. We need a good THz/far-IR orbiter telescope to be able to see cold objects
I got the impression that they were ruling out natural explanations too quickly in order to get to the unnatural explanation. Suppose they do not get any radio emissions? Would that rule out a civ with a Dyson swarm? I don’t think so, just that transmissions are not receivable by our radio telescopes. So worth looking, but a signal is an unlikely outcome.
My other thought is that if we are so soon able to detect other civilizations, then just a few thousand years from now we will have extraordinary powers of observing other stars, and a few tens of thousands of years later we could monitor a big chunk of the galaxy with remote probes as well. In which case other civs can monitor us very easily. Only the limitations of c keep us from the more troubling consequences of that.
Interesting finding.
Hopefully the last hypothesis to take into account is the right one. But I don’t kid myself: this is most likely a recent comet collision as the paper says.
Nevertheless…
A ring of sunshades eclipsing a star’s light in a periodic pattern, fits the kind of activity classical SETI was expecting to find. Showing a developing Kardashev level I to II civilization.
And not that far away in astronomical terms either. Well it may be impossibly far if you want to go there, but the fact we possibly found another civilization with our own primitive instruments, indicates this is really not that far.
Which makes me wonder: won’t such a hypothetical civilization have found us by now?
If we could see their activity from here, very likely they could see at least Earth from there with their hyper advanced telescopes, the fruit of maybe uncountable millennia of technical development ahead of us. Well, they could at least see Earth as it was more than a thousand years ago, but even the Earth of two millennia ago was teeming with life and emitting the signatures of that life into space, in the planetary light spectrum, for anyone with an advanced telescopes to find.
Which makes me think: if these are really aliens, couldn’t they be intentionally aligning their sunshades for signaling their presence to us, given the relative proximity of this?
A random civilization nearby that has artifacts precisely aligned with our Sun giving us the shadow of their sunshades by chance looks like an incredible coincidence to me.
That or they are common as dirt, which goes against other observational evidence telling us they aren’t (at least not civilizations going into the Kardashev level III path).
So I conclude that if these are indeed aliens (a big assumption), the fact they show in Kepler data by being precisely aligned with our Sun, indicates they are at least aware of us.
I have not had a lot of time to absorb everything in the paper but could it potential be a bloated asteroid belt caused by a planet in orbit. If we look at what Jupiter’s is doing to the asteroid belt and Neptune to the Kuiper belt it might be possible. Asteroid belt discs can be turned into doughnuts easily enough and would not need to be edge on so much to see the effects that we see.
https://www.youtube.com/watch?v=kSqYk6yD75I
@CharlesJQuarra, assuming that ET is setting up shades or collectors, 100AU seems like an awful long way away from the source of the energy you’re collecting. But anyway, if they’re smaller and out very far, aren’t they more likely to be just debris or comets? Assuming you were building collectors, you’d probably place them closer in, which in this case would make them larger, and less likely to be comets… would any of the comets that we’re familiar with in our system even cause a detectable dip for a detector in some other system looking back our way? I guess what I’m thinking is, wouldn’t it have to be a dang huge, planetary-sized comet, to produce those sorts of occultations??
Your remarks suggest that this occurred over the space of a few years. Is that correct? This seems sudden on stellar scales. Would exo-comets change their orbits that quickly? On the other hand, what civilization could build a Dysonian contraption that quickly?
Reminds me of TYC 8241 2652 and its disappearing “debris field”.
From the Bad Astronomer: “They can be very deep; one dropped the amount of starlight by 15 percent, and another by a whopping 22 percent!”
My first thought was that it could be a ringed planet.
By the way, from the paper, “[h]owever, clumps that are
too distant move too slowly across the stellar disk to explain the ob-
served duration regardless of their size; e.g., a 3-day duration dip
cannot arise from a clump beyond ~ 15 AU.”
The Bad Astronomer – Phil Plait – take on this discovery:
http://www.slate.com/blogs/bad_astronomy/2015/10/14/weird_star_strange_dips_in_brightness_are_a_bit_baffling.html
To quote:
As reported in the Atlantic (which is what started all the social media interest in the first place), Wright and Boyajian are indeed proposing to use a radio telescope to look for signals from the star. An alien civilization building such a structure might leak (or broadcast!) radio waves that could be detectable from 1,500 light-years away. That’s the whole basis of SETI, the Search for Extraterrestrial Intelligence (see the movie Contact, or better yet read the book, for more on this). Telescope time is controlled by a committee, and it’s not clear if the proposal will pass or not. I hope so; it shouldn’t take too much telescope time, and under modest assumptions it shouldn’t be too hard to detect a signal.
Only wake me if a pair of Stars Suddenly winks out, within a 200 light years, then I will be worried about a Pandora’s Star (PF Hamilton) scenario.
I recall reading that a ring world would be a first step in building
a Dyson Sphere. It always struck me as a strange thing to do, because
if you can make Artificial Gravity with your Dyson apparatus. Then you
don’t need to stay in your star system now do you.
Our solar system does contain populations of fairly large objects with orbits that are unstable on (in astronomical terms) short timescales, most obviously the centaurs, which will end up being scattered by the giant planets either out of the solar system or into the inner system.
As regards NGC 5907, it appears that consideration of the point-spread function of the observing instruments may remove the need to invoke exotic stellar populations, see Sandin (2014).
If a Dyson sphere were composed of a number of separate objects in orbit, is it possible we would “see” a glittering effect in the optical or radio signal as the objects passed on the opposite side of the star? Perhaps a series of small spikes caused by flat surfaces? I wouldnt expect to see this effect from fuzzy dust, or rounded debris and boulders.
@beermotor
“But anyway, if they’re smaller and out very far, aren’t they more likely to be just debris or comets?”
exactly my point. I think this could be a natural explanation that I didn’t see mentioned in the paper. Granted, if the debris chunks are actually smaller than, say, a Pluto or an Eris, there is no way they are orbiting the same star: they probably would have to be closer to us than KIC 8462852 in order to cause such a deep transit
On the other hand, if the debris are bigger than a planetoid, they ought to be round, and the transit pattern ought to be symmetric, which they weren’t, which means they are not round-shaped
the mystery continues
It’s nice to see media mentioning this and the topic of detection of other possible civilization through mega-engineering structures being treated seriously.
However it should be noted, that this isn’t the first case of possible Dyson Sphere candidates(as most Centauri Dreams readers probably know), at the end of the day the issue is ability to confirm the findings which at the moment we largely lack.
http://home.fnal.gov/~carrigan/infrared_astronomy/Other_searches.htm
I’ll be interested to see Wright’s paper. Hopefully they’ll suggest more possible natural causes.
I’d like to see them model the effects of a massive object in the foreground (e.g. small black hole with no active accretion disk). Seems that gravitational lensing caused by something in front of it could cause dips this pronounced, but ought to have other signatures that distinguish it from a solid object.
Whatever is going on, it certainly warrants ongoing observation.
They might know there is some sort of life and liquid water on Earth…but they would see Earth of 500 not a lot of civilizational impact. On the other hand we see them …if its a them….of 1500 years ago with a technology 500 or so years or more even if we get serious about advancing ourselves again…..Think where they are now since its very likley that we could send a small laser sail in century based on what I have read here in CD….maybe we should look for laser or microwave activity and see if they are sending out probes …..I am sure we would at least send out probes to fly by interesting planets if we had emerging K 2 civ…..
What’s the likelihood that an errant starless Jupiter-sized planet, or brown dwarf with its own cohort of satellites can be slingshot into a star system?
“Only wake me if a pair of Stars Suddenly winks out, within a 200 light years, then I will be worried about a Pandora’s Star (PF Hamilton) scenario.”
^Around 1000 light years actually.
Of course it’s obvious to have the right answer if we wait for about 1500 years (duh!). Is a collision of two planets which had unstable elliptical orbits in the star system more or less likely than LGM?
“IF” this an Alien super structure. When it passes between KIC 8462852 and Earth, it should be possible to get what is basically an Xray image of what every it is. Just find a wavelength from the star that will pass through the structure and start to see what it looks like.
Hi, I often read but rarely comment.
Is there any chance that this is something very odd about the star itself, not sunspots, but actual light emission variability? Not sure how well characterized this particular star is in itself, but is it possible that we have a lot of weirdness in stellar diversity if we look close-up, just as we are finding for exoplanets?
Thanks as always for this wonderful website, and its haven of polite, intelligent internet discussion!
This light curve only happened on one star out of 150,000 or so in the Kepler survey. I would guess we got lucky and there is a rogue planet on the line of sight. With the right proper motions, considering Kepler’s motion in space, this might work.
I wonder if there is an evolutionary phase of mature hot jupiters that might throw off large sums of material.
A natural explanation seems the be the most likely one – there’s enough data to suggest a variety of them but not enough data to confirm any single one. At the same time, I’m glad that there’s serious consideration given to the possibility of extraterrestrial intelligence at work and how they might be detected beyond radio and laser signals. Given how the potential for ET fires the imagination (especially mine!), I appreciated and must applaud tchernik’s comments. Presuming the swarm of objects is ET, So we’re seeing what this level I shifting to level II civilization was doing around 530 AD Earth time. I wonder how far their project has come along in the intervening time!
I just read Phil Platt’s take on this. Something that is NOT mentioned anywhere here, is that there DOES appear to be a PERIODIC dip in the lightcurve of about 20 days that is MUCH SHALLOWER than the ones mentioned here during the first few quarters, but then, these dips dissapear COMPLETELY in the mid and later quarters! The explanation given for these dips is that they were due to a starspot. Not being an expert in starspots, I am not challenging this concluision, but I do find it hard to believe that a starspot can COMPLETELY DISSAPEAR in just 20 days! Someone PLEASE correct me if I am wrong in my reasoning. If it is NOT a starspot, is there any other NATURAL explanation? If not, wouldn’t that lead to a K2 civilization messing with the brightness of the star for some reason?
Did they observe a large dip in April 2015? If we see another in May 2017, then it’s more likely a close-in, big object (still not sure about the “shearing result of giant impact” hypothesis, given that should show a lot of glow in the infrared, right?).
BACK AGAIN! Phil Platt ALSO mentioned in his post that this is a BINARY star system(the secondary star being ONLY 130 billion kilometers away). Is there anything strange about THAT star(in the Kepler light curves or anywhere else). Could the periodic dip mentioned in my previous comment be attributable to a HUGE starspot on the secondary? ALSO: assuming that the red dwarf secondary(i.e., was NOT captured) couldn’t you determine the age of the PRIMARY by finging out the age of the secondary. FINALLY: It is conceivable that, if there IS a K2 civilization building megastructures around the primary, that it could have ORIGINATED on a planet orbiting the secondary.
tchernik:
“If we could see their activity from here, very likely they could see at least Earth from there with their hyper advanced telescopes, the fruit of maybe uncountable millennia of technical development ahead of us. Well, they could at least see Earth as it was more than a thousand years ago […]”
If hypothetical astronomers near KIC 8462852, 1480 light years away, are observing the Earth, they would see the planet as it was in the year 535 AD. The pyramids at Giza and the Great Wall of China are visible from space. Large sections of the Wall (about half) were built during the Qin dynasty (221-206 BC) and the Han dynasty (206 BC-220 AD). Could objects of this size (or ancient cities like Rome or Byzantium) be seen from 1480 light years away?
@Harry and others
The only natural explanation I can think of at this time is that these could possibly be effects consistent with a star swallowing a planet that was pushed out of orbit, via collision or slingshotted into inner orbit, dragging other objects along with it, and destabilising the star’s system.
If I would be some enterprising young astronomer building a career, I wouldn’t be politely waiting to see if that VLA time can be gotten by this team and instead would seek time from other radio telescopes myself – after first checking if there isn’t in archives any existing material on this star on radio-wavelengths.
Commons sense may be very uncommon on planet like Earth that’s what creators of this anomaly would say. There is no harm in looking at the possibility that if this is only such anomaly in light curve of this weird star among 156000 stars then it could be possibly a signal , a complex code which only advanced civilization would be able to create in anticipation of technologies around them at vast distances trying to build elementary tools like Kepler telescope ( they must have done the same thing with their own Keplers- so if a powerful code cracking software is used to critically analyse the time series data of complex or chaotic random dips then perhaps a code may emerge, a pattern may emerge and it may even give a simple message to our species- YOU FOUND US. I think most advanced civilization would create such complex riddles in space like this… and aim is to give our species some homework. So those who are good in code cracking could have go on time series of the strange light curve and give it a try…. it could be CONTACT-II.
I have just one question,light emitted from that star actually takes around 1480 years to travel to earth so this means these dips currently noted on telescope should have occurred around 1480 years before from now means that comets or whatever it is it was there 1480 years before,is that right???
bhupender, that’s correct. We are seeing light that was emitted about 1480 years ago.
The thing is, beermotor, there isn’t a lot of infrared observed, at least not as much as you’d expect if the phenomena were due to dust and the usual accretion disk.
ala Benford’s living star theory. Perhaps they are little stellar offspring running around their parent in a chaotic manner! ;)
@TLDR, right. I’m not buying the comet explanation. It seems like the occultation’s just too huge. And it seems like the constraints on orbits from the paper show that it’s probably not something small and far away from the star, rather it’s something big and relatively close in. So what we think we know is that it’s really enormous, it’s dark, it’s not infrared-bright (cool/cold?), and it may or may not be periodic. If it IS periodic, and it is cool/cold, and it is big, . . . . that makes it pretty interesting, no?
I wonder if you could see a flash from a reverse/opposition orbit, if it was a collector of some type? Have they checked to see if the stellar variability peaks up at intervals opposite to the occultations? If it was metal, of any type, there should be some sort of reflectivity, right? Heck, the salts on Ceres were very bright (~40% reflectivity).
@Harry R Ray October 15, 2015 at 10:00
‘Could the periodic dip mentioned in my previous comment be attributable to a HUGE starspot on the secondary? ALSO: assuming that the red dwarf secondary(i.e., was NOT captured) couldn’t you determine the age of the PRIMARY by finging out the age of the secondary. FINALLY: It is conceivable that, if there IS a K2 civilization building megastructures around the primary, that it could have ORIGINATED on a planet orbiting the secondary.’
Sun spots can obscure large areas of red dwarfs but not F types as their rotations rates are more sedate, I never have heard of an F type doing that.
If we are entertaining the idea of possible civilization, than it would be interesting to measure the frequency of the dips and compare with any mathematical pattern or equation.
Marko Amnel-they would certainly be able to detect our biosphere. As to signs of civilization, really depends on the scale of their telescopes and methods. The star is really far though, I am not sure they would be able to detect visible changes at the time to Earth’s surface, or illumination of cities that existed at the time.
What would the best follow-up study be to this result, and what would it cost?
Wojciech J: “…it would be interesting to measure the frequency of the dips and compare with any mathematical pattern or equation.”
This would be like finding an equation for a line that passing through several data points. There are an infinite number of them. It would take a lot more data to statistically establish the likelihood that any one equation, or category of equations, is substantially greater than all the others.
Dear Paul
What a wonderful post! And what great responses. After Kelvin Long graciously sent me the link to the Daily Mail piece, I downloaded and printed the archived paper by Tabetha Boyajian and 28 co-authors.
I then went to my ancient, partial copy of Dole’s Habitable Planets for Man, 2nd. ed. From p.68 of this venerable text, I learned that F3V stars have a main sequence life expectancy of about 3 billion years. So the evolution of advanced life is not impossible.
Section 4.4.3 of the paper implies that the orbital distance of the occulting objects from the central star can be interpreted from the data to be about 1.6 AU. Table 11 of Dole reports that the ecosphere for an F3V star ranges 1.44-2.08 AU.
I look forward very eagerly to the SETI telescope’s examination of this star. All natural causes for this phenomenon should be carefully considered, as the authors of the paper and commenters to the blog posting have begun to do.
But it is not impossible that Kepler has observed signs of a very advanced technological civilization. If that turns out to be true, it is a great pity that they ate so distant. Unless they have FTL (which I consider very unlikely), direct contact is impossible. What a shame!
Regards, Greg
@afeder
Some next steps might be a concentration of SETI efforts, as Greg mentioned. I understand this is scheduled for January.
We have Kepler’s transit data; perhaps radial velocity observations will give us an idea of the mass of the unknown objects.
Finally, more continued viewing and gathering of more data will help us figure this out. Perhaps there is a pattern to these occultations that will begin to make sense over time.
Great stuff!
Forgive my ignorance, but why can’t the anomaly be directly observed by the Hubble ST ?
BTW- Thank you all for the for the intelligent discussion. I have enjoyed reading all of your posts!
Wojciech J:
“Marko Amnel-they would certainly be able to detect our biosphere. As to signs of civilization, really depends on the scale of their telescopes and methods. The star is really far though, I am not sure they would be able to detect visible changes at the time to Earth’s surface, or illumination of cities that existed at the time.”
Well, if such a civilization really exists, they might have telescopes with apertures several kilometres across (or more). How well could they see the surface of the Earth with telescopes that big?
Here is a little picture I made that helped me to visualize where KIC 8462852 is located:
http://postimg.org/image/76e26e5st/
There is a big yellow arrow pointing right at it. It is located to the left of Gamma Cygni, which is about 1800 light years away in the constellation Cygnus. Thanks to Richard Powell for the image of the Orion Arm I used as a base. Wikipedia says that “KIC 8462852 in Cygnus is located in the sky roughly halfway between the major visually apparent bright stars Deneb (? Cyg, ? Cygni, Alpha Cygni) and Rukh (? Cyg, ? Cygni) to the eye as part of the Northern Cross. […] With an apparent magnitude of 11.7, the star cannot be seen by the naked eye.”
https://en.wikipedia.org/wiki/KIC_8462852
I should read more thoroughly next time, this star is rotating in 21 hrs! I though it was 88 days so star spots are quite likely which may describe the noisy light flux. But a star spot that reduces the light flux by around 20 % would be very unusual unless they all came together at the same time which again would be unlikely. Now due to the fast rate of rotation the star is most likely still young and therefore advanced life would be less likely.
We can’t say anything about the likelihood of life around a star based on its age. Saying life is less likely around a young star just assumes that the only life we’ll find is what developed in situ. We don’t know that to be the case. /shrug
I mean, let’s assume it’s a structure being built. A civ with the capacity to build a structure that big could have come from somewhere else. They may have purposefully moved to a brighter/younger star for energy purposes.
Chances are it’s some sort of enormous debris field, but as the paper and others have stated, you’d expect that to be IR-bright. Maybe it’s very exotic dust (a shattered diamond planet!).
I still think checking for periodicity flashes on the backside is a good idea. If it is in orbit and it is metallic, you’d think there’d be some upticks / flashes in brightness right before it goes around behind. Those may be harder to see than occultations, though, I don’t know. (As a lawyer/former geologist, I need an acronym for “I am not a scientist”–IANAS? heh.)
@beermotor October 16, 2015 at 9:40
‘We can’t say anything about the likelihood of life around a star based on its age. Saying life is less likely around a young star just assumes that the only life we’ll find is what developed in situ. We don’t know that to be the case. /shrug’
Multi cellular life only occurred around 2 billions years ago, that would be a substantial amount of the stars lifespan due to its mass. This star due to it rapid rotation is fairly young.
‘Chances are it’s some sort of enormous debris field, but as the paper and others have stated, you’d expect that to be IR-bright. Maybe it’s very exotic dust (a shattered diamond planet!).’
Diamond is transparent to optical light and infrared.
‘I still think checking for periodicity flashes on the backside is a good idea. If it is in orbit and it is metallic, you’d think there’d be some upticks / flashes in brightness right before it goes around behind. Those may be harder to see than occultations, though, I don’t know. (As a lawyer/former geologist, I need an acronym for “I am not a scientist”–IANAS? heh.)’
They would be harder to see depending on their shape and distance from the star but it would be as you say be harder to see than an occlusion.
Now ice does reflect light pretty well and if it is past the stars snow/ice line it will remain solid and highly reflective. It would still need to be quite large though, a ringed planet on it side maybe. We will just need to look at it more with other instruments. Saturn has a ring structure that is quite large~250 000 km wide which would be a substantial size of the stars diameter and it can block a lot of light.
‘Saturn’s C Ring
…That is, between 5 and 12 percent of light shining perpendicularly through the ring is blocked, so that when seen from above, the ring is close to transparent. The 30-kilometer wavelength spiral corrugations first seen in the D Ring were observed during Saturn’s equinox of 2009 to extend throughout the C Ring (see above).’