A KIC 8462852 (dipping again in March 2018)

[nikkkom]

Unfortunately, that's drifting into an area where
a] it requires the invocation of an unprecedented phenomenon - and even granting that -
b] it still requires some tortured explanations (such as smoothness and periocity) in even make it fit our fantastic phenomenon.

The point is, I don't see any periodicity of the dimming events in the data.

There was one nearly 20% dimming event, then some 700 days later a group of three other dimming events first of which was even deeper. Each of four events has a different shape.

That's why I thought "these are probably not transits at all" and came up with my pet theory.

 

[DaveC426913]

The point is, I don't see any periodicity of the dimming events in the data.

There was one nearly 20% dimming event, then some 700 days later a group of three other dimming events first of which was even deeper. Each of four events has a different shape.

OK, starspots have the distinction of not needing to have a highly-constrained periocity. I'll give it that.

 

[DaveC426913]

Point of order:
Everywhere I've used the word periocity, you should be hearing periodicity in your head.

 

[Michael Lazich]

Some really intriguing light curves here. Read the article for some explanation.

http://www.slate.com/blogs/bad_astr...ge_dips_in_brightness_are_a_bit_baffling.html

Look at the smooth curve lower left. That has got to be a single body transit. Multiple bodies couldn't make such a smooth curve. Yet that body results in a 15% drop in the light curve!
And it's cold, so not a companion star.

I don't see how exo-comet fragments can explain this.

Black dwarf?

I've been struck how the lower left curve looks like what could be produced by a spinning disk or other object...

Black Monolith anyone...? ;)

 

[mfb]

I've been struck how the lower left curve looks like what could be produced by a spinning disk or other object...

How?

 

[rootone]

Maybe a really massive companion planet which itself has several very large moons orbiting it?

 

[Michael Lazich]

How?

Actually, the cross sectional area of a spinning disk could be said to have the "general" shape of the light curve, and that for only a single rotation.

The light curve from a star with such a spun disk in front of it would actually look like the inverse of what was observed from KIC 8462852.

I just calculated the cross section of a spinning disk with the dimensions such that, at full occultation, the light from the star would be around 84% of its maximum value; as it rotates through 180 degrees, the occulting area varies as cosine of the rotation angle and you get the curves below:

Of course, the actual observations are asymmetrical and are the *inverse* of the light curve that would be produced under the assumptions above.

Just thought it was interesting.

 

[mfb]

I don't see where you imagine a disk and how spinning that disk would be relevant.

 

[Michael Lazich]

I don't see where you imagine a disk and how spinning that disk would be relevant.

 

[newjerseyrunner]

That looks like you're describing a flipped coin. Discs don't spin that way, there is no physical way for anything like that to naturally form. Discs spin along their plane, that's what makes them discs in the first place: angular momentum.

 

[Michael Lazich]

That looks like you're describing a flipped coin. Discs don't spin that way, there is no physical way for anything like that to naturally form. Discs spin along their plane, that's what makes them discs in the first place: angular momentum.

No kidding. My posts were never about any sort of natural explanation for the observed light curve. Nor are they meant as a serious argument for an unnatural explanation.

Hence my original reference to a Black Monolith.

Which is a reference to the movie 2001, where a spinning alien structure is shown orbiting Jupiter.

Good movie, you should see it.

Just an offhand observation that people seem to have taken too literally.

 

[DaveC426913]

Hence my original reference to a Black Monolith.
Which is a reference to the movie 2001, where a spinning alien structure is shown orbiting Jupiter.
Good movie, you should see it.
Just an offhand observation that people seem to have taken too literally.

I confess I too missed a reference to the monolith. Must have been a ways back.

I thought we were still discussing explanations and offering sincere ideas.

 

[nikkkom]

Maybe a really massive companion planet which itself has several very large moons orbiting it?

With star having 1.5 Sun's diameter, the "planet" which can occult 22% of star's disk needs to have diameter of more than half Sun's diameter - IOW, ~5 Jupiter diameters.

Such planets don't exist.

 

[rootone]

With star having 1.5 Sun's diameter, the "planet" which can occult 22% of star's disk needs to have diameter of more than half Sun's diameter - IOW, ~5 Jupiter diameters.

Such planets don't exist.

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?)

 

[nikkkom]

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?)

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

HAT-P-32b - 2.037 (± 0.099) Rj
"CT Chamaeleontis b is slightly larger at 2.2 Jupiter radii, but may be a brown dwarf star."

And this is a 2 day orbit planet with nearly 2000K surface temps, strongly thermal-puffed.

Thus, 2x Jupiter is about as big as planet can be.

 

[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.