Our galaxy's most-mysterious star is even stranger than astronomers thought

October 3, 2016, Carnegie Institution for Science
This artist's conception shows a star behind a shattered comet. One of the theories for KIC 8462852's unusual dimming is the presence of debris from a collision or breakup of a planet or comet in the star's system, creating a short-term cloud that blocks some starlight. Credit: NASA/JPL-Caltech.

A star known by the unassuming name of KIC 8462852 in the constellation Cygnus has been raising eyebrows both in and outside of the scientific community for the past year. In 2015 a team of astronomers announced that the star underwent a series of very brief, non-periodic dimming events while it was being monitored by NASA's Kepler space telescope, and no one could quite figure out what caused them. A new study from Carnegie's Josh Simon and Caltech's Ben Montet has deepened the mystery.

Simon and Montet's findings caused a stir in August, when they were posted on a preprint server while their paper was being reviewed. Now their work is now accepted for publication by The Astrophysical Journal.

The researchers analyzed further Kepler observations of the puzzling star and showed that in addition to its rapid unexplained brightness changes, the star also faded slowly and steadily during the four years it was watched by Kepler.

Speculation to explain KIC 8462852's dips in brightness has ranged from an unusually large group of comets orbiting the star to an alien megastructure. In general, can appear to dim because a solid object like a planet or a cloud of dust and gas passes between it and the observer, eclipsing and effectively dimming its brightness for a time. But the erratic pattern of abrupt fading and re-brightening in KIC 8462852 is unlike that seen for any other star.

Spurred by a controversial claim that the star's brightness gradually decreased by 14 percent from 1890 to 1989, Montet and Simon decided to investigate its behavior in a series of Kepler calibration images that had not previously been used for scientific measurements.

"We thought that these data could confirm or refute the star's long-term fading, and hopefully clarify what was causing the extraordinary dimming events observed in KIC 8462852," explained Simon.

Brightness of KIC 8462852 as a function of time. The solid line represents the authors' best estimate of the brightness of the star during the Kepler mission, while the shaded region represents the uncertainty on the brightness at any time. The authors find the star's brightness slowly decreased over time until early 2012, when it rapidly dimmed in brightness by 2 percent over six months. Credit: Ben Montet.

Simon and Montet found that, over the first three years of the Kepler mission, KIC 8462852 dimmed by almost 1 percent. Its brightness then dropped by an extraordinary 2 percent over just six months, remaining at about that level for the final six months of the mission.

The pair then compared this with more than 500 similar stars observed by Kepler and found that a small fraction of them showed fading similar to that seen in KIC 8462852 over the first three years of Kepler images. However, none exhibited such a dramatic dimming in just six months, or a total change in brightness of 3 percent.

"The steady brightness change in KIC 8462852 is pretty astounding," said Montet. "Our highly accurate measurements over four years demonstrate that the star really is getting fainter with time. It is unprecedented for this type of star to slowly fade for years, and we don't see anything else like it in the Kepler data."

"This star was already completely unique because of its sporadic dimming episodes. But now we see that it has other features that are just as strange, both slowly dimming for almost three years and then suddenly getting fainter much more rapidly," Simon added.

Astronomers were already running short of good ideas to account for the dips in KIC 8462852's brightness, and the new results will make that task even harder. Simon and Montet think that the best proposal so far for explaining the star's drastic six month dimming might be a collision or breakup of a planet or comet in the star's system, creating a short-term cloud of dust and debris that blocks some starlight. However, this wouldn't explain the longer-term dimming observed during the first three years of Kepler and suggested by measurements of the star dating back to the nineteenth century.

"It's a big challenge to come up with a good explanation for a star doing three different things that have never been seen before," Montet said. "But these observations will provide an important clue to solving the mystery of KIC 8462852."

Explore further: Latest study of Tabby's star offers more weirdness

More information: arxiv.org/abs/1608.01316

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23 comments

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Tuxford
1 / 5 (12) Oct 03, 2016
"The steady brightness change in KIC 8462852 is pretty astounding," said Montet. "Our highly accurate measurements over four years demonstrate that the star really is getting fainter with time. It is unprecedented for this type of star to slowly fade for years, and we don't see anything else like it in the Kepler data."

OK then, here is an idea: The star is grown from within large and active enough to be ejecting material therefrom at an ever increasing rate so that the ejected material congests near the star and obscures the star at an ever increasing rate. This process would likely continue until a point in the growth cycle where the ejecting winds therefrom increase to a point that they clear out the nearby material, causing the star to brighten again.

Likely this process occurs periodically in the life cycle of a star, where the obscured phase lasts only a relatively short period of time. Thus, few stars are observed during this period of the cycle.
hemitite
4.9 / 5 (24) Oct 03, 2016
What wasn't mentioned in this article was that there is little or no IR radiation emanating from this star. Clouds of dust would be glowing brightly in that range. My theory: that star is surrounded by odd socks and missing tupperware lids.
eachus
5 / 5 (2) Oct 04, 2016
How about a protostar condensing in front of Tabby's Star? The dust would be cold enough not to have emission lines, and absorption lines would be similar to those for the background star, Hmm. No guarantee, but split absorption lines should show if such a cloud is moving toward or away from us at a different rate than the background star.

A very unlikely scenario--but with a whole galaxy to study, one incident is not too unlikely.
Gigel
4.5 / 5 (8) Oct 04, 2016

OK then, here is an idea

That is probably the first theory that posits that a star can grow (quite slowly by the measured data) and at the same time become dimmer. Besides, you fail to present the mechanism of growth from within, with proofs of its existence. Occam's razor would have a hard time even considering this theory.
big_hairy_jimbo
3.3 / 5 (4) Oct 04, 2016
Stab in the dark. Might the star be changing it's fusion recipe to other elements or in the process of doing so?
Tuxford
1.4 / 5 (9) Oct 04, 2016

OK then, here is an idea

That is probably the first theory that posits that a star can grow (quite slowly by the measured data) and at the same time become dimmer. Besides, you fail to present the mechanism of growth from within, with proofs of its existence. Occam's razor would have a hard time even considering this theory.

Thanks for the credit. Clearly you offer more insight than most here, including the local science police. The mechanism is SQK theory. So if you are really interested, bone up!

Physics does not have the tool set to explain it. Physics is stuck inside a mirrored hall with no exit, while the solution lies outside the room itself. So you will likely never be satisfied if you remain inside the hall. Be brave. Explore new worlds!
TheGhostofOtto1923
not rated yet Oct 04, 2016
As far as megastructures are concerned, Niven again comes to mind.
http://scifi.stac...e-bowl-b

-A shipstar nearing completion. Is it moving?
bobbysius
not rated yet Oct 04, 2016
maybe a small foreground dust cloud, far enough from the star not to glow in IR, but enough to extinct some of it's light? Or aliens? Probably aliens
sponskater
5 / 5 (2) Oct 04, 2016
Stab in the dark. Might the star be changing it's fusion recipe to other elements or in the process of doing so?

I don't think that it is the right age to do so. It's main sequence which means it would be changing from Hydrogen to Helium. But from what I remember the diameter is too small, and it won't be changing elements for a few hundred million years.

I think the most likely natural explanation is a relatively small cloud of dust a few light years away from us. I would like to do the math on a the range of sizes to block out 22% of the light at different distances, but I am too lazy; I think it is just simple trigonometry though.
Gigel
5 / 5 (4) Oct 05, 2016
The mechanism is SQK theory.

Any laboratory evidence for that?
antialias_physorg
5 / 5 (4) Oct 05, 2016
Might the star be changing it's fusion recipe to other elements or in the process of doing so?

A move towards burning helium should be accompanied with an increase in brightness.
paulk190
1 / 5 (1) Oct 05, 2016
Cygnus? That's Veil nebula territory. My guess is that this star is being obscured by that.
Tuxford
1 / 5 (8) Oct 05, 2016
The mechanism is SQK theory.

Any laboratory evidence for that?

Ah, back inside the mirrored hall, eh? I thought maybe you had more potential. Was I wrong??

Perhaps physics will expand the hall one day to include the solution, but I fear that may be decades from now. Why wait? Dip in the water. Be brave.

After all, if the shoe fits, might there be something there worth considering? I am simply fitting the SQK cosmology shoes to the observations. I am hopeful that LaViolette's magnetic thruster experiment might soon shed some light on the subject. Still, if so, watch the science police cast the evidence aside, as usual.
Gigel
5 / 5 (6) Oct 05, 2016
A theory without evidence is a fairy tale. And SQK sounds like being able to produce laboratory evidence (it's quantum after all). So it either comes with verifiable predictions that are then checked, or it is fairy tale, and many people around here can come with different fairy tales to explain whatever they want to. So then, why would this SQK be better than other possible theories out there?
Phys1
4.2 / 5 (5) Oct 05, 2016
@Tuxford
Was I wrong??

You always are.
Tuxford
1 / 5 (5) Oct 05, 2016
@Tuxford
Was I wrong??

You always are.

Yep, I was. Gave too much credit. What happens to you guys when SQK turns out to be right. What then will you say?

Proof has nothing to do with reality, at least not necessarily. It is only satisfying to the uncertain mind. And the nature of knowledge about reality is ever-changing. Reality is likely not changing, at least within our lifetimes. So limited is the insight of the overly rational mind, that it cannot see the forest for the trees. Imagination is stymied, and insight is severely restricted to within the hall of mirrors.

What if the the nature of reality is that it does not lend itself to a simple lab experiment? Newton could not detect the atom in his lab, and yet it still existed.
Gigel
5 / 5 (2) Oct 06, 2016
Tuxford, scientists are uncertain. They are not born with certainties. In matters of science, proof is needed. At least for now; maybe in 1000 years the philosophy of science would have changed its basis so much that proof won't be necessary any more. But for now, that is what science means.

When SQK will turn out to be right we'll have proof of it. That is what I'm asking for.
bschott
not rated yet Oct 06, 2016
That is probably the first theory that posits that a star can grow (quite slowly by the measured data) and at the same time become dimmer.


Um...you are aware of the theoretically projected life cycle of our sun right? Comparing where it is at now to it's theorized final phase...did it get brighter or dimmer?
Osiris1
1 / 5 (3) Oct 06, 2016
All you guys sound like the personification of the fairy tale: "The Emperor's New Clothes". NO ONE wants to say the 'A' word and it IS the 800 pound gorilla in the room. ALIENS, get it!!!!? I SO expect a chorus of 'one's as this is a way for brown nosers of fools to keep their jobs.
Gigel
5 / 5 (2) Oct 06, 2016
Um...you are aware of the theoretically projected life cycle of our sun right? Comparing where it is at now to it's theorized final phase...did it get brighter or dimmer?

As far as I know, the Sun got brighter in time. In fact there is a mystery why the Earth was not frozen early in its existence: https://en.wikipe..._paradox
AdamSea
1 / 5 (3) Oct 06, 2016
It's just vibrating faster now, than you can see in the moment. Gravity is a lens that never closes. Only right spinning photons blink.
Gigel
5 / 5 (3) Oct 07, 2016
I wonder: why don't crooks attack each other? They keep appearing, each one with a different theory, yet they seem to be in perfect harmony with each other. They only jump at the throat of established science.

That's why I actually think that, intentionally or not, they are just trolls. What they care for most is to troll the largest number of people. It's not the truth, but the fight that drives them. This is not a discussion area for them, but an ecosystem in which they try to be the main predators and dominate everyone else.
Mazarin07
not rated yet Oct 07, 2016
I never heard about SQK before.
Subquantum Kinetics. wtf?
http://www.intern...t=199951

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