KIC 8462852 (dipping again in March 2018)

[newjerseyrunner]

I missed the bit about the star being 1.5 Sun's diameter, but out of curiosity ...
How big can a planet get before it must inevitably become a star?
I'm sure I heard that some exoplanets have been found which are larger than Jupiter, although not 5 times larger.
(Yes I know the answer depends a lot on the density and composition, but is 5x Jupiter completely out of the question for a gas giant predominantly made of hydrogen?)

A weird thing about very small stars and other substellar objects is that when you increase their mass, you actually decrease their volume. Gravity makes them denser and denser until fusion stars, at which point there is something actually pushing back besides pressure. A large planet or mass has also been ruled out because a large object's gravitational affects on the star itself would be detectable.

 

[inuk2600]

The flux appears to go above 1.0 at day ~1550. If this is comets with highly reflective coma, could it produce an increase in flux as it swings around to the other side of the star?
Also would a highly reflective coma also account for the lack of infrared?

 

[mfb]

The whole light curve is a bit variable, the normalization to 1 is arbitrary. I wouldn't interpret too much in tiny upwards deviations.

 

[Ely Paiva]

Please, could anyone kill my curiosity. From observations in Earth (from large observatory telescopes or amateur astronomers like AAVSO)
how big is the dip we can register ? Something like 5% for large telescopes and 15% for amateur astronomers?

 

[DaveC426913]

Please, could anyone kill my curiosity. From observations in Earth (from large observatory telescopes or amateur astronomers like AAVSO)
how big is the dip we can register ? Something like 5% for large telescopes and 15% for amateur astronomers?

What do you mean?

The dip is a decrease in brightness of the disc over time. One dip we've seen reduced the apparent magnitude of the star by about 22%. So, for some arbitrarily normalized value set to 1, we've seen it decrease to 0.78.

An amateur telescope would need an adidtional device that could accurately read the relative magnitude of a star, but it might have a larger margin of error (such as,say, 20% +/- 5%), but I'm not sure what you mean by 5% versus 15%.

 

[Ernest S Walton]

I think at this time it's worth reminding ourselves just how accurate the Kepler light curves are. In Kepler-444 for example, 5 planets smaller than Venus and orbiting closer than Mercury could all be deciphered from blips in the light curve. So a 22% deviation is colossal.

 

[nikkkom]

https://en.wikipedia.org/wiki/Next-Generation_Transit_Survey

This is the newest transit search project done with "amateur" scale telescopes (20cm), but by professionals (and with "professional" funding). They say they achieve ~0.1% photometric precision.

 

[Ely Paiva]

What do you mean?

The dip is a decrease in brightness of the disc over time. One dip we've seen reduced the apparent magnitude of the star by about 22%. So, for some arbitrarily normalized value set to 1, we've seen it decrease to 0.78.

An amateur telescope would need an adidtional device that could accurately read the relative magnitude of a star, but it might have a larger margin of error (such as,say, 20% +/- 5%), but I'm not sure what you mean by 5% versus 15%.

Thank you! I

What do you mean?

The dip is a decrease in brightness of the disc over time. One dip we've seen reduced the apparent magnitude of the star by about 22%. So, for some arbitrarily normalized value set to 1, we've seen it decrease to 0.78.

An amateur telescope would need an adidtional device that could accurately read the relative magnitude of a star, but it might have a larger margin of error (such as,say, 20% +/- 5%), but I'm not sure what you mean by 5% versus 15%.

 

[Ely Paiva]

Thank you! I

Thank you ! I was wondering which of those dips in light could have been seen from telescopes in Earth (professional or amateur). I don't think they would like to send another kepler observatory to the sky... The guys below also sent me some hints. I understand that amateurs will be able to see only the "big dips" (if they occur again), but professional telescopes may do a good follow up presumably. My guess is some kind of intrinsic variability phenomena we don't know yet.

 

[mfb]

I don't think they would like to send another kepler observatory to the sky

They do! Not with the same target area of course, because that would be pointless. And with an improved sensitivity, obviously.
This star will certainly be monitored by multiple telescopes now.

Self-quote:

NASA works on TESS, roughly 3 times the number of stars Kepler watched, with a focus on bright stars nearby.
ESA is planning PLATO, it will observe 7 times the number of stars Kepler watched, over a much larger area in the sky so it can focus on brighter (and closer) stars as well.
CHEOS is another ESA spacecraft , with a focus on accurate radius measurements for planets that have been discovered before.

 

[Ely Paiva]

They do! Not with the same target area of course, because that would be pointless. And with an improved sensitivity, obviously.
This star will certainly be monitored by multiple telescopes now.

Self-quote:

Great ! Good to know !

 

[Pdgenoa]

Things seem to have gone silent. Does anyone know if we're all just in waiting mode for the ATA and various other observational results? Searching around online hasn't really given me a good feel for why the non-media outlets have become so quiet.

 

[rootone]

Things seem to have gone silent. Does anyone know if we're all just in waiting mode for the ATA and various other observational results? Searching around online hasn't really given me a good feel for why the non-media outlets have become so quiet.

Seems like that to me.
There isn't much more to say until there is more data available.

 

[Ernest S Walton]

Apparently some high resolution spectrography has been carried out and no excess of dust was uncovered. This could just be the result of any dimming bodies being absent at the time. Also keep an eye on the aavso campaign: https://www.aavso.org/apps/webobs/results/?star=kic+8462852&num_results=25&obs_types=all. If the V mag drops below 12.0 then sound the alarm:)

 

[Dryson1]

Could the result in the dim of KIC be a result from the same type of matter found in the article link below traveling across the face of KIC or somewhere in between KIC and Kepler?
http://www.space.com/4271-huge-hole-universe.html

I'm all for the aliens idea.

What if the objects around KIC 8462852 were solar reflector arrays not meant to gather energy but to be used as a beacon? If you think about it a radio signal would take years to arrive at a targeted planet if the signal ever arrived at all. But one signal that would arrive for certain and at the speed of light would be the reflected or dimmed sun. An alien species could build an array that would orbit a sun where the array could be used to block out or reflect the light in such a way to cause attention to be drawn to sun. The array could even be built where the reflection could be dimmed by adjusting the panels on the array the same way that the signal lights in the wiki article link below work just on a larger scale.

https://en.wikipedia.org/wiki/Signal_lamp

Has anyone thought to take the various percentages of drops in light of KIC and apply those percentages to letters of the alphabets of planet Earth even those no longer in use? What about the Periodic Table of Elements? If the dim is a result of aliens then the percentages of light that were discovered might in fact be a form of Morse Code.

 

[rootone]

If as you suggest it's some kind of purposefully engineered 'lighthouse' kind of beacon, or even some more sophisticated kind of broadcast signalling apparatus,
then it isn't very useful as such, since any recipients of the signal will not be getting the message in most cases until hundreds or thousands of years after it is sent.
It would then take hundred or thousands of years for them to reply, (assuming they had a similar messaging apparatus in the first place.),
and to travel physically to the location could take up to millions of years.

 

[Chronos]

This went up on arxiv today http://arxiv.org/abs/1511.01606, Radio SETI Observations of the Anomalous Star KIC 8462852. The long and short of it is - no anomalous radio signals have been detected. So if ET is signaling, it is apparently limited to waving a blanket in front of the camp fire. I can't picture a scenario where an intelligent ET would resort to such a crude [and apparently costly] means to signal their presence without a radio transmission. I would expect a deliberate signal would at least include a loud broadband radio chirp as evidence something more than a peculiar transit event was going on.

 

[DaveC426913]

Could the result in the dim of KIC be a result from the same type of matter found in the article link below traveling across the face of KIC or somewhere in between KIC and Kepler?
http://www.space.com/4271-huge-hole-universe.html

You have misread the article. Scientists found a hole - a lack of matter - not the presence of matter. So no, a lack of matter between KIC and us would not dim the star.

I'm all for the aliens idea.

What if the objects around KIC 8462852 were ...

There is not a lot of point in surmising what an alien might want to do with their star. The hypothesis that the dimming is caused by an alien construct is sufficient to cover the case.

 

[mfb]

Could the result in the dim of KIC be a result from the same type of matter found in the article link below traveling across the face of KIC or somewhere in between KIC and Kepler?
http://www.space.com/4271-huge-hole-universe.html

The article is about a region in space far away with a lower than average density. No, nothing like that is between the star and us (we are in the same galaxy!), and a lower density of matter would not block light.

What if the objects around KIC 8462852 were solar reflector arrays not meant to gather energy but to be used as a beacon? If you think about it a radio signal would take years to arrive at a targeted planet if the signal ever arrived at all. But one signal that would arrive for certain and at the speed of light would be the reflected or dimmed sun. An alien species could build an array that would orbit a sun where the array could be used to block out or reflect the light in such a way to cause attention to be drawn to sun. The array could even be built where the reflection could be dimmed by adjusting the panels on the array the same way that the signal lights in the wiki article link below work just on a larger scale.

Visible light and radio waves travel at the same speed. With the effort you need to dim a star by 20%, you could make an incredibly strong radio transmission.

Has anyone thought to take the various percentages of drops in light of KIC and apply those percentages to letters of the alphabets of planet Earth even those no longer in use? What about the Periodic Table of Elements?

The dimming is not a clear sequence of well-separated events, even if you clarify how this "apply" is supposed to look like it cannot work.
Also, the fractions of light blocked will look different from different viewing directions.

 

[typical guy]

They didn't find signals as pathetically low as 100 and 10,000,000 times TOTAL TERRESTRIAL ENERGY USAGE. Are they making the assumption that aliens are trying to contact us? I ask because when they sent that signal, if they were able to optically observe earth, we were in the year 1000BC and today when they see us, the Romans are ruling the Mediterranean.

I find it highly unlikely that a species advanced enough to build a Dysons Cluster would be wasting so much energy communicating with their construction teams just because they have so much energy available. It's completely absurd and renders the whole experiment useless.

 

[mfb]

Are they making the assumption that aliens are trying to contact us?

They are not. They test it, because alien life there sending radio messages is not impossible.

If the light curve is the result of some mega-engineering (and that is a really large "if"), then the engineers are aware that their project is highly visible to possible observers around millions of stars. It is also not unreasonable to expect that they discovered Earth and did spectroscopy of our atmosphere. Our large oxygen content together with methane and various weird molecules from our chemical industry is at least a strong indication of life or even a potential technological civilization.
If you cannot avoid being visible (due to the construction of something), why not send a message along? A directed message needs orders of magnitude less power than an undirected emission.

 

[PhysicsFan11]

The question is one of regularity. Does the light dissipation occur at regular intervals or at random? Is there a reduction in light exactly the same quantitatively each time?
Has there been a proposal that the the light reduction is coming from the star itself; temporary reduction in its corona for example due to a collapsing phenomenon?

 

[Borg]

The question is one of regularity. Does the light dissipation occur at regular intervals or at random? Is there a reduction in light exactly the same quantitatively each time?
Has there been a proposal that the the light reduction is coming from the star itself; temporary reduction in its corona for example due to a collapsing phenomenon?

If you read through this thread from the beginning, you will see that all of this has been discussed along with multiple graphics. There have been two events about 800 days apart. None of the proposed explanations fits exactly but the scenario where the star is responsible is highly doubtful and it is the least likely scenario. It appears that something really big passed in front of the star but even that doesn't completely make sense based on the current analysis. The first passage was a very sharp change in the light curve and the second was more irregular which makes the breakup of a body the most likely. Without re-reading everything, I believe that the next 800 day event is in 2017. That event should help to clarify what's going on.

 

[PhysicsFan11]

Thanks for the synopsis Borg,
It seems to me that the Dyson sphere or any alien object would be the least likely scenario and be 'ruled in' only after every possible scenario has been ruled out.
Assuming that the Dyson sphere, if it existed, was unchanging, then the second passage should have been similar to the first. Perhaps a previously unknown stellar body of enormous size, and like you stated , in the process of breaking up, would be the most plausible scenario.

 

[stooch]

You know what problem i have with this theory? It takes more resources, know-how and technological advancement to surround a star with a Dyson sphere than it is to develop a fusion reactor. Which is basically what the star is...how would one overcome the force of the solar wind, gamma radiation, thermal radiation and magnetic fields as they surround the star with a HUGE amount of material. Why do that when efficiency of photovoltaics is a small fraction of the total energy output. And this is before the losses you will incur from when you transmit the energy back to your planet. How will it affect the ecology of their planet now that they have blocked a huge portion of sunlight? The whole notion is ridiculous. Any "advanced" race wouldn't bother with an invention we humans came up with decades ago because we did not deem fusion feasible at the time. My money is on cloud of dust, and i can't believe that this is actually taken seriously by anyone in the scientific community. Then again, I'm not a scientist so maybe I'm just totally off with my assumptions.

 

[typical guy]

You know what problem i have with this theory? It takes more resources, know-how and technological advancement to surround a star with a Dyson sphere than it is to develop a fusion reactor. Which is basically what the star is...how would one overcome the force of the solar wind, gamma radiation, thermal radiation and magnetic fields as they surround the star with a HUGE amount of material. Why do that when efficiency of photovoltaics is a small fraction of the total energy output. And this is before the losses you will incur from when you transmit the energy back to your planet. How will it affect the ecology of their planet now that they have blocked a huge portion of sunlight? The whole notion is ridiculous. Any "advanced" race wouldn't bother with an invention we humans came up with decades ago because we did not deem fusion feasible at the time. My money is on cloud of dust, and i can't believe that this is actually taken seriously by anyone in the scientific community. Then again, I'm not a scientist so maybe I'm just totally off with my assumptions.

I agree that it's almost certainly something other than a megastructure (i.e. It's natural).

That being said, I just don't think it's possible to predict what would be needed in terms of energy for a civilization that is a million or a hundred million years ahead of us. I'm sure Homo Errectus looking at us from a mountaintop would say that surely it would be easier to chop wood and burn it for heat and light than to search the planet for natural gas and build technologies and transport systems for heating and electric use. For all we know, they could be so far ahead that it's simply impossible to understand their motivations without having a better grasp of their situation. Part of the reason for a Dyson Sphere is to increase real estate. The planet can only physically hold so many humans but if you encircle the sun you can suddenly have quadrillions of people.

 

[mfb]

how would one overcome the force of the solar wind, gamma radiation, thermal radiation and magnetic fields as they surround the star with a HUGE amount of material.

Solar wind is completely negligible. Light pressure is a bit more, but you need a ridiculously thin shell to note the effect at all compared to gravity. Gamma radiation from the sun is negligible, and the effect of the magnetic field is very small as well.

Why do that when efficiency of photovoltaics is a small fraction of the total energy output.

The sun has much more fuel than the whole planetary system.

And this is before the losses you will incur from when you transmit the energy back to your planet.

Why should you do that?

How will it affect the ecology of their planet now that they have blocked a huge portion of sunlight?

Even if the planet doesn't get disassembled in the process, the shell could be built at a larger radius.

Any "advanced" race wouldn't bother with an invention we humans came up with decades ago because we did not deem fusion feasible at the time.

If you expect that future for the Dyson sphere, why do you expect they would use fusion - something we discovered before Dyson was even born?

My money is on cloud of dust, and i can't believe that this is actually taken seriously by anyone in the scientific community.

The scientific community is discussing natural explanations. An alien civilization is not even mentioned in the original publication, for example.

 

[newjerseyrunner]

I agree that it's almost certainly something other than a megastructure (i.e. It's natural).

That being said, I just don't think it's possible to predict what would be needed in terms of energy for a civilization that is a million or a hundred million years ahead of us. I'm sure Homo Errectus looking at us from a mountaintop would say that surely it would be easier to chop wood and burn it for heat and light than to search the planet for natural gas and build technologies and transport systems for heating and electric use. For all we know, they could be so far ahead that it's simply impossible to understand their motivations without having a better grasp of their situation. Part of the reason for a Dyson Sphere is to increase real estate. The planet can only physically hold so many humans but if you encircle the sun you can suddenly have quadrillions of people.

I don't think it's "taken seriously" by anyone. Exploring it as a possibility and thinking it's even probable are different. SETI didn't do a study because they thought there might be something there, they did it because that's their job and they wanted to lessen the possibility of it being aliens.

 

[inuk2600]

I don't think it's "taken seriously" by anyone. Exploring it as a possibility and thinking it's even probable are different. SETI didn't do a study because they thought there might be something there, they did it because that's their job and they wanted to lessen the possibility of it being aliens.

I don't follow, why?

 

[mfb]

It is the most likely result of the search they did. Sure, a signal would have been much more interesting, but also very unlikely.

The same is done in particle physics, for example: the existing model is extremely good in making predictions. With every measurement you hope to find some deviation, but the expectation is always to just find agreement with the prediction, with a better precision than previous experiments.

 

[PhysicsFan11]

While I personally do not believe it is an alien /artificial object, whatever it is has not been seen with light observations from other star systems. So this uniqueness does make it very intriguing.

 

[mfb]

It has not been seen in 150,000 other stars observed for a few years. It could be an event as frequent as once per million years for every star (on average). Kepler is not the only telescope watching the sky, but even a factor of 10 less would still mean those events could be extremely common on astronomical timescales.

Edit: This doesn't take into account the limited visibility - it is probably not an event that produces dimming in every direction. Similar events could occur even more often because we just see some small fraction of it, where the fraction depends on the distance of the shadowing objects.

 

[Borg]

For those in the Northern Virginia area, there is an astronomy session for the public at a local university (George Mason) today. The topic will be Time Domain Astronomy which, according to Wikipedia is the study of astronomical object change with time. The 1/2 hour talk will be given by http://science.gsfc.nasa.gov/sed/bio/neil.gehrels of the NASA Goddard Space Flight Center. I'm really curious whether KIC 8462852 will be mentioned.

 

[Borg]

The talk was nice. Really enjoyed it.

Back on topic...

 

[Ely Paiva]

What do you think about the hypothesis published in the site below ?
The author claims about a kind of "spheroidal shape" star, a gravity darkened star with different
grades of brightness in poles and equator. He suggests then multiple planets crossing this kind of
non uniformly brightness star. The page shows some interesting figures (simulations).
Still in this case, I argue that it would be necessary to be some kind of enormously uncommon planets
to decrease 22% in brightness. It also does not explain the irregular variations in brightness.
What do you think about this hypothesis?
http://www.desdemonadespair.net/2015/10/did-kepler-space-telescope-discover.html