Weird lights, might be aliens (KIC 8462852)

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Weird lights, might be aliens (KIC 8462852)

Sources:
1. The Most Mysterious Star in Our Galaxy, The Atlantic
2. Has Kepler Discovered an Alien Megastructure?, Discovery News
3. Planet Hunters X. KIC 8462852 - Where's the Flux?, arXiv
4. KIC 8462852, Wikipedia

The Most Mysterious Star in Our Galaxy, The Atlantic, has posted a story about a weird star. Other news sources have also seized on The Atlantic's lead with more explicit alien stories.

Astronomers looking for exoplanets watch stars. Occasionally, a star might dim, suggesting that there's something like a planet in the way. Keep watching the star, and you can start guessing how many planets there are with what oribital periods based on the pattern. You can start guessing their sizes based on how dark the star gets (like smaller planets won't block as much light). Based on a planet's size and orbital period, along with what you know about the star, you can start guessing its mass, composition, etc. This can lead to news stories about new Earth-like exoplanets being found.

Astronomers have noticed that one star, KIC 8462852, has this luminosity time series:
.
So what's up with that weird set of spikes in the lower-right-hand figure? Doesn't look much like a single, large planet.

Astronomers aren't sure since the grouping of them suggests that it's a lot of clustered objects orbiting the star together. And some folks think that this might be those alien megastructures other researchers were looking for.

Has Kepler Discovered an Alien Megastructure?, Discovery News, provides a more educated perspective. Planet Hunters X. KIC 8462852 - Where's the Flux?, arXiv, has a PDF from the researchers.
Natural ChemE
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Re: Weird lights, might be aliens

Just to avoid misleading, I'm posting this story because it's silly fun. There's no legitimate reason to think aliens.

The megastructures the news stories mention are basically huge solar panels that should surround a star and collect most of its light:
Dyson sphere, Wikipedia wrote:A Dyson sphere is a hypothetical megastructure that completely encompasses a star and hence captures most or all of its power output.

This is a very different observation. Whatever's there, it captures a very, very small fraction of the overall light - that maximum dip in normalized luminosity is 22%, and very brief.

The actual researchers think that it's probably a bunch of fragments from a comet breaking up.
Natural ChemE
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Re: Weird lights, might be aliens

Aw, phooey! I thought you meant they were coming here.
Who cares what they're building way over there?
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Re: Weird lights, might be aliens (KIC 8462852)

Some day it'd be funny to read a story like this that pitches the idea of cosmic topological defects like cosmic strings. The artistic conception pictures would be awesome.

However, I suppose that this would just be silly. Clearly, even if it is cosmic strings, the aliens made 'em. Through time travel back to the beginning of the universe where they asserted symmetry violations, just to screw with the standard model.

If Star Trek has taught us anything, it's that anthropocentrism is a totally legitimate world view. We should completely expect hyper-advanced aliens to largely resemble our current form. We are the pinnacle of evolution, and though gadgets may get cooler, ultimately all advanced life will always be fundamentally like us - just with space ships.

Sorry, I get weird when I'm procrastinating. Not a clue why I do this.
Natural ChemE
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Re: Weird lights, might be aliens (KIC 8462852)

Hey NCE,

I can't say I've reach much about this (or astronomy in general) so this could be a silly question. However, when I was looking at the graphs, and before I saw your comment on what the interpretation could be, this popped into my mind. What if the angle between our orbital plane and that of the distant planet isn't fixed? Would the planet be covering a varying area of the star each time it passes between it and us? Basically, I am wondering whether changes in dimming intensity necessarily mean multiple orbiting objects of varying sizes (unless of course they have distinct periods).

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Re: Weird lights, might be aliens (KIC 8462852)

Hi, BioWiz. Given the star's F class, any single object passing across would spike no more than 1 percent, maybe 2, and be quite regular regardless of orbital plane. (orbital planes don't shift around all that quickly, anyhow) A Jovian planet, larger than Jupiter, would spike no more than 1 percent. If there were something enormous enough to give that 22% spike, it would have other gravitational and spectral effects - like a binary system with a red dwarf. It's clearly many cold objects drawn into a tight orbit - the cometary chunks theory looks pretty strong right now. What you need, to get 22%, is some dispersion but retaining a fairly high density to block a lot of radiation.

In the ArXiv paper, they are predicting another dipping event in May 2017, and hoping to do more extensive measurements which might reveal cometary tellatles - a comet barrage (possibly unleashed by the gravitic nudge of a passing star) would mean not only icy chunks and grains of dust, but gas, and sensitive tests could determine the presence of cometary gases. What impresses me is that we've reached the point where this kind of observation can be made at 1480 LY distance. Just the other day I was reading something that reminded me we don't even know if Proxima C., only 4.2 LY away, has planets. There is a body of theory about red dwarfs, very long-lived stars (trillions of years), that considers them possibly having close-orbiting tidally-locked planets that could harbor life, esp. in terminator zones. Climate zones could exist in concentric rings around the substellar point.
Last edited by TheVat on October 15th, 2015, 12:18 pm, edited 1 time in total.
Reason: typo fixed

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Re: Weird lights, might be aliens (KIC 8462852)

Hey BiV,

First, same disclaimer as above. Then, some follow up questions.

Since I was asking about changes in what the graphs are calling normalized flux, I wasn't basing any part of my question on the absolute value of the effect. The dip is how the presense of orbiting planets (or megastructures?) is being deduced, correct? And this dimming effect would increase rapidly as the planet's size and distance from the star increases. Right? So I'm more asking out of general curiosity about how thse problems are approached.

As for the orbit, I was thinking about some sort of complex orbit rather than a simple orbit rapidly changing over time. Does that make sense?

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Re: Weird lights, might be aliens (KIC 8462852)

I do see how what you're saying about the extent of the effect feeding into the conclusion that it's not a single object though.

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Re: Weird lights, might be aliens (KIC 8462852)

A dimming effect decreases with distance from the primary. Think about how much radiation would strike the daylight face of a planet at a given distance - that's how much radiation is being blocked. If Earth were orbiting at, say, 0.05 AU (inside the orbit of Mercury), it would receive, thus block, more radiation that it would at 1 AU or 10 AU (out beyond Jupiter). So, for a solid body to caused a 22% dipping event, it would have to incredibly huge and in a very tight orbit. The orbit would be not too complex, and its periodicity would be measured in days or weeks. Everything about this data suggests the aftermath of a big messy disruption from an exocomet or comets, tossed inward by a passing star perhaps, and a big resulting smear of light-blocking junk in a fairly close orbit. Again, not sure what you mean by complex. The originating event would be complex, as multiple bodies are involved, but the smashed-up comet junk would likely not be terribly eccentric (as intact comets often are) in its orbit.

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Re: Weird lights, might be aliens (KIC 8462852)

Braininvat » 15 Oct 2015 11:51 am wrote:A dimming effect decreases with distance from the primary. Think about how much radiation would strike the daylight face of a planet at a given distance - that's how much radiation is being blocked.

That is true when the light source is smaller than the blocking object. However, when the light source is bigger than the blocking object, the inverse is true. As you get farther from the light source, the rays become more and more parallel, and the blocking object is able to block more of the rays that can otherwise reach a point behind it along the line that connects the centers of the light source and the object.

Think of it this way. If you're looking up at the sun, you can hold a pan over your face and that'll block all the sun rays from hitting your face directly. Now move the pan farther from your face and closer to the sun. Its shadow will get smaller as it moves closer towards the sun.

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Re: Weird lights, might be aliens (KIC 8462852)

That sounds wrong to me, at least when we are dealing with stellar distances. But I'm out of time here, and our most able explainers/astronomy buffs (Darby, Marshall) seem mostly absent lately. Given the relative distances of 1480 LY, and the relatively tiny distance of stellar system objects, I'm not sure your optical model is right. To be continued....

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Re: Weird lights, might be aliens (KIC 8462852)

Braininvat

Maybe this image will clarify what I mean.

http://www.pa.uky.edu/sciworks/qlight.htm wrote:

Maybe I'm missing something. Hopefully someone will figure out what.

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Re: Weird lights, might be aliens (KIC 8462852)

Would the solar eclipse be dimmer or brighter had the moon been much farther away from the Earth, and much closer to the sun?

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Re: Weird lights, might be aliens (KIC 8462852)

Braininvat » 15 Oct 2015 11:51 am wrote:If Earth were orbiting at, say, 0.05 AU (inside the orbit of Mercury), it would receive, thus block, more radiation that it would at 1 AU or 10 AU (out beyond Jupiter). So, for a solid body to caused a 22% dipping event, it would have to incredibly huge and in a very tight orbit. The orbit would be not too complex, and its periodicity would be measured in days or weeks. Everything about this data suggests the aftermath of a big messy disruption from an exocomet or comets, tossed inward by a passing star perhaps, and a big resulting smear of light-blocking junk in a fairly close orbit. Again, not sure what you mean by complex. The originating event would be complex, as multiple bodies are involved, but the smashed-up comet junk would likely not be terribly eccentric (as intact comets often are) in its orbit.

Another question is how are we measuring this dimming effect? By the above explanation, we'd have to measure the total radiation emitted (in all directions) to detect a bigger dimming effect from an object absorbing more of the source's radiation at a closer distance. If, on the other hand, we're detecting it from a point in space behind the intervening object (which I assume is the case), then we're more talking about the kind of scenario I mentioned above - i.e, specifically how much radiation is reaching the region of space directly behind the object rather than the total amount of radiation absorbed by the object itself. No?

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Re: Weird lights, might be aliens (KIC 8462852)

BioWizard,

I'd look at it like this:
1. The star, KIC 8462852, is a light bulb.
2. The obstruction, perhaps a planet, is a sticker.
3. Someone stuck the sticker on the light bulb, reducing how much light we see from it.
Since both the star and obstruction are very far away (in this case 1500 light years), it's almost like the obstruction was right on top of the star. Technically there's some gap between the star and its obstruction, so the obstruction can be slightly smaller while still blocking all light.

Working under the approximation that all parts of a star's projected area project the same light to an observer, then a 22% reduction in light suggests that the obstruction has 22% of the projected area of the star. Assuming that both are spheres, then
${{A}_{\text{obstruction}}}{\approx}0.22{{A}_{\text{star}}}$,
so
${{r}_{\text{obstruction}}}{\approx}{\sqrt{0.22}}{{r}_{\text{star}}}$,
and
${{V}_{\text{obstruction}}}{\approx}{{0.22}^{\frac{3}{2}}}{{V}_{\text{star}}}{\approx}0.103{{V}_{\text{star}}}$,
so the obstruction would have about 10% of the volume of the star, assuming that it's a sphere.

By contrast, rocky planets like Mercury don't really block much of the sun's light even if lined up because they're tiny. Their projected area is a small fraction of the sun's. It might be different if a gas giant like Jupiter were in the way; quick calculations using Wikipedia's numbers for volume for the sun and Jupiter would make Jupiter about a 1% reduction in light under the directly-on-top-of-projection-surface approximation, i.e. how folks in other solar systems would see Jupiter when looking at the sun's luminosity profile.

I think that issues like this contribute to why it's so hard to find small, rocky (Earth-like) exoplanets. They're too small in volume to significantly block light and too small in mass to cause the star to wobble a lot (which is another way folks looks for exoplanets).
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Re: Weird lights, might be aliens (KIC 8462852)

Natural ChemE » 15 Oct 2015 01:53 pm wrote:Assuming that both are spheres, then
${{A}_{\text{obstruction}}}{\approx}0.22{{A}_{\text{star}}}$,
so
${{r}_{\text{obstruction}}}{\approx}{\sqrt{0.22}}{{r}_{\text{star}}}$,
and
${{V}_{\text{obstruction}}}{\approx}{{0.22}^{\frac{3}{2}}}{{V}_{\text{star}}}{\approx}0.103{{V}_{\text{star}}}$,
so the obstruction would have about 10% of the volume of the star, assuming that it's a sphere..

Ok, so all radiation is treated as coming to us in straight lines from the source at that distance, and the dimming effect is far more dependent on the radius of the planet (relative to the radius of the star) than its distance from the star. Gotcha. Thanks!

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Re: Weird lights, might be aliens (KIC 8462852)

Natural ChemE » 15 Oct 2015 01:53 pm wrote:Since both the star and obstruction are very far away (in this case 1500 light years), it's almost like the obstruction was right on top of the star. Technically there's some gap between the star and its obstruction, so the obstruction can be slightly smaller while still blocking all light.

That bit agrees with what I was saying earlier about how increasing the gap between the star and a smaller obstruction will increase the extent of dimming for something that's right behind the obstruction (so in your example, the slightly smaller object would only partially obstruct the star if it were right up against it, but can fully obstruct it when there's a gap between them).

However, since we're treating the radiation reaching us as being virtually collimated due to the vast distance from the star/planet system, can anything smaller than an equally sized object fully obstruct the star's radiation?

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Re: Weird lights, might be aliens (KIC 8462852)

...treating the radiation reaching us as being virtually collimated due to the vast distance from the star/planet system....

Yep, that is the key. Sorry I didn't clarify that. So, yes, it usually requires an equal sized binary to fully block. NCE's analogy is a nice one.

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Re: Weird lights, might be aliens (KIC 8462852)

BioWizard » October 15th, 2015, 2:25 pm wrote:However, since we're treating the radiation reaching us as being virtually collimated due to the vast distance from the star/planet system, can anything smaller than an equally sized object fully obstruct the star's radiation?

I guess that we've got a few types of size to consider:
1. amount of mass;
2. amount of volume;
3. amount of projected area.
The luminosity data really speaks to projected area. Assuming that the star's actual, unobstructed luminosity is fairly constant, then changes in the luminosity profile map to changes in the obstruction's projected area.

For a simple planet, we'd kinda expect more simple, smooth dips.

If it's a binary system, e.g. two massive planets orbiting each other, then their projected area can vary by about 50% (full when both planets are fully obstructing, 50% when they're lined up).

If it's a $n$-body system of equal projected area, e.g. many planets or a cloud of asteroids, then their projected area can drop down to $\frac{1}{n}$ when all lined up compared to their max.

If it's a cloud of debris, then the projected area can be huge for the mass due to the low density.

If it's non-spherical, e.g. like if it really is an alien superstructure solar panel, then its profile will vary with its angle. We'd expect alien solar panels to be normal to the star, so it should have a sharper peak than a spherical obstruction would.

If it's interacting clouds of debris, then it can be both low-mass and have $n$-body effects. I think that this is what the astronomers' current best guess.

If it's a relativisticly-massive obstruction, then it can bend the light even if it's super-small in terms of projected area (e.g. a black hole). However that's not the case here since such massive objects would be pulling around the star.

Personally I'd also be curious about space weather on the star itself, like starspots (which can be much more dramatic than sun spots). This particular star could have some sort of weather phenomena that we just don't know about yet. Those things aren't very well understood, even on the sun.
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Re: Weird lights, might be aliens (KIC 8462852)

lol @ alien solar panels

Multiple body systems and non spherical objects were kind of what I was wondering about (not just in the context of this particular case, but in general with this kind of problem)

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Re: Weird lights, might be aliens (KIC 8462852)

Braininvat » 15 Oct 2015 02:54 pm wrote:
...treating the radiation reaching us as being virtually collimated due to the vast distance from the star/planet system....

Yep, that is the key. Sorry I didn't clarify that. So, yes, it usually requires an equal sized binary to fully block. NCE's analogy is a nice one.

Yeah. It wasn't a necessary premise for my original question, but it was good to remember. Thanks BiV.

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Re: Weird lights, might be aliens (KIC 8462852)

Yeah, I think that this sorta topic's fun to joke around about. For example, I'm gonna start using:
steampunkism: The belief that all future technology is describable as improved, scaled-up variations of modern technology.
'cause, you know.. lots of folks seriously are looking for alien solar panels, apparently presuming that that's how aliens would harness energy.

I like to think that these stories are really just for fun to get folks interested, like Lincoln's book on aliens. Discovery News actually has an article about the profiles from these sorts of structures:
.
This article's from 2011, so I guess folks have been looking for this stuff for quite a while now.
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Re: Weird lights, might be aliens (KIC 8462852)

I like this "Steampunkism" word. In other venues, people expressed the same idea regarding our misconceptions of the far future. In other venues (e.g. reddit) people have also noticed that the actual research papers on KIC star never mention anything about aliens.

.

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Re: Weird lights, might be aliens (KIC 8462852)

Hi all,

Could the anomaly be produced by a massive number of large sun spots on one side of the Star?

Regards,
Dave :^)

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Re: Weird lights, might be aliens (KIC 8462852)

Dave, you have to consider several questions here...

1. Would sunspots (cooler areas of photosphere) give the same spectral signature as radiation being partially blocked by orbital junk?

2. Would sunspots cluster on one side of a main sequence (or any) star, so as to make a down spike like this one?

3. Would any photosphere anomaly drop radiative output 22 %?

I have some guesses on these questions, but I want to research a bit before saying more, given that anomalies are, well, anomalies. :-)

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Re: Weird lights, might be aliens (KIC 8462852)

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Re: Weird lights, might be aliens (KIC 8462852)

Dave_Oblad » October 19th, 2015, 3:08 pm wrote:Hi all,

Could the anomaly be produced by a massive number of large sun spots on one side of the Star?

Regards,
Dave :^)

Probably not. The rotation period of KIC 8462852 is less than one day. Regular, small order fluctuations of the same period suggest star spots. These are quite different from the anomalies that have provoked so much comment.
The favored explanation for the aperiodic deep dips in light output, one or more disrupted comets, has been questioned on several bases. Among these:
1.) Could a reasonable amount of cometary material cause its star to dim by as much as 22 percent?
2.) If there were enough material present to accomplish this unprecedented degree of dimming, might it not be reasonable to expect to find remnants of the dust from the comet(s)? Excess dust in this star system has been looked for repeatedly, but not found.
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Re: Weird lights, might be aliens (KIC 8462852)

I'd say the answer to (1) is that we don't know, because we have had only one solar system and Scattered Disc /Kuiper Belt to monitor up close, so far. Before we start filling our knowledge gap with Dyson structures, it would be good to look at all scenarios where large debris fields can be created. And there may be more of those than we've yet conceived of. Some which wouldn't involve a lot of gas/dust....perhaps a fairly tight formation of rocky material which will in due course form an asteroid belt? I'd like to browse the lit some more, see what sorts of speculation might later prove testable. Post em if you got em...

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Re: Weird lights, might be aliens (KIC 8462852)

The paper by Boyajian, et al, which is linked at the start of this thread, considers a non-cometary explanation for the star-dimming bodies. The problem they see here is apparently the likelihood that asteroid fields will have modest numbers of large objects, and gradually increasing numbers of smaller and smaller objects, right down to dust.
Given the expectable history of collisions of asteroids in a mature system, like this, it's hard to see how such a distribution could be avoided. They expected that dust from such an asteroid field should have been detectable.
This would apparently be doubly so in a scenario that involves very dense clusters of asteroids, such as could dim a star by up to 22 percent. Repeated observations have not found excess dust in this star system.

One form or another of cometary scenario seems to be the only natural one being actively considered at this time.
I agree that most gaps in our knowledge will probably, eventually be filled by natural phenomena.
In this particular case, though, there seems to be a bit of room for the possibility of a non-natural explanation. The KIC 8462852 star system has now been examined for radio and laser transmissions. Further radio astronomy work of this sort is proposed for 2016, with more sensitive instruments.
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Re: Weird lights, might be aliens (KIC 8462852)

It seems that Tabby's Star (KIC 8462852) has a new mystery for us to solve. The observation records for this star, for the years 1890 to 1989, were carefully gone over. It was found that the star had steadily dimmed by 16 percent in those 99 years. This is unprecedented in an F star on the main sequence, which Tabby's Star is held to be.

Suppose we hold to the favorite explanation for the dimming of this star, disrupted comets blocking its light. About 648,000 giant comets, each about 200 kilometers (120 miles) in diameter would have had to pass in front of the star. Further- their numbers would have to increase over time, to account for the progressive dimming of the star.
Alternatively we could be watching a Dyson swarm being built, with 16 percent more star light collected, and, so, blocked from our view, in the course of a century. Given the distance of the star, this would have been happening about 1500 years ago.

link to a scientific paper on this, below:

http://arxiv.org/abs/1601.03256
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