New study supports natural causes, not alien activity, explain mystery star's behavior

May 9, 2016 by David Salisbury, Vanderbilt University
Cascading comets around a distant star. Credit: NASA/JPL/Caltech

Sorry, E.T. lovers, but the results of a new study make it far less likely that KIC 8462852, popularly known as Tabby's star, is the home of industrious aliens who are gradually enclosing it in a vast shell called a Dyson sphere.

Public interest in the star, which sits about 1,480 light-years away in the constellation Cygnus, began last fall when Yale astronomer Tabetha ("Tabby") Boyajian and colleagues posted a paper on an astronomy preprint server reporting that "planet hunters" - a citizen science group formed to search data from the Kepler space telescope for evidence of exoplanets - had found unusual fluctuations in the light coming from the otherwise ordinary F-type star (slightly larger and hotter than the sun).

The most remarkable of these fluctuations consisted of dozens of uneven, unnatural-looking dips that appeared over a 100-day period indicating that a large number of irregularly shaped objects had passed across the face of the star and temporarily blocked some of the light coming from it.

Media interest went viral last October when a group of astronomers from Pennsylvania State University released a preprint that cited KIC 8462852's "bizarre light curve" as "consistent with" a swarm of alien-constructed megastructures.

The attention caused scientists at the SETI Institute to train its Alien Telescope Array on the star to see if they could detect any radio signals indicating the presence of an alien civilization. In November it reported finding "no such evidence" of signals with an artificial origin.

Then a study released in January by a Louisiana State University astronomer threw even more fuel on the fire of alien speculation by announcing that the brightness of Tabby's star had dimmed by 20 percent over the last century: a finding particularly difficult to explain by natural means but consistent with the idea that aliens were gradually converting the material in the star's planetary system into giant megastructures that have been absorbing increasing amounts of energy from the star for more than a century. That study has now been accepted for publication in the peer reviewed Astrophysical Journal.

However, a new study - also accepted for publication in the Astrophysical Journal - has taken a detailed look at the observations on which the LSU study was based and concluded there is no credible evidence that the brightness of the star been steadily changing over this period.

The Dyson Ring, left, is the simplest form of Dyson structure. Creating a Dyson bubble would be an incredible engineering challenge but it is considered to be far more feasible than surrounding a star in a rigid sphere. Credit: Wikipedia Creative Commons License

When the LSU study was posted on the physics preprint server ArXiv, it caught the attention of Vanderbilt doctoral student Michael Lund because it was based on data from a unique resource: Digital Access to a Sky Century @ Harvard. DASCH consists of more than 500,000 photographic glass plates taken by Harvard astronomers between 1885 and 1993, which the university is digitizing. Lund was concerned that the apparent 100-year dimming of Tabby's star might just be the result of observations having been made by a number of different telescopes and cameras that were used during the past century.

Lund convinced his advisor, Professor of Physics and Astronomy Keivan Stassun, and a frequent collaborator, Lehigh University astronomer Joshua Pepper, that the question was worth pursuing. After they began the study, the Vanderbilt/Lehigh group discovered that another team - German amateur astronomer Michael Hippke and NASA Postdoctoral Fellow Daniel Angerhausen - were conducting research along similar lines. So the two teams decided to collaborate on the analysis, which they wrote up and submitted to the Astrophysical Journal.

"Whenever you are doing archival research that combines information from a number of different sources, there are bound to be data precision limits that you must take into account," said Stassun. "In this case, we looked at variations in the brightness of a number of comparable in the DASCH database and found that many of them experienced a similar drop in intensity in the 1960's. That indicates the drops were caused by changes in the instrumentation not by changes in the stars' brightness."

Even if aliens are not involved, Tabby's star remains "the most mysterious star in the universe" as Boyajian described it in a TED talk she gave last February.

The planet hunters first detected something unusual in the star's light curve in 2009. They found a 1 percent dip that lasted a week. This is comparable to the signal that would be produced by a Jupiter-sized planet passing in front of the star. But planets produce symmetric dips and the one they found was decidedly asymmetric, like something that would be produced by an irregular-shaped object like a comet.

The light from the star remained steady for two years, then it suddenly took a 15 percent plunge that lasted for a week.

Another two years passed without incident but in 2013 the star began flickering with a complex series of uneven, unnatural looking dips that lasted 100 days. During the deepest of these dips, the intensity of the light coming from the star dropped 20 percent. According to Boyajian it would take an object 1,000 times the area of the Earth transiting the distant star to produce such a dramatic effect.

"The Kepler data contains other cases of irregular dips like these, but never in a swarm like this," said Stassun.

Boyajian and her colleagues considered a number of possible explanations, including variations in the star's output, the aftermath of an Earth/Moon type planetary collision, interstellar clumps of dust passing between the star and earth, and some kind of disruption by the star's apparent dwarf companion. However, none of their scenarios could explain all of the observations. Their best explanation was a giant comet that fragmented into a cascade of thousands of smaller comets. (This hypothesis took a hit when the LSU study was announced because it could not explain a century-long dimming.)

"What does this mean for the mystery? Are there no aliens after all? Probably not! Still, the dips found by Kepler are real. Something seems to be transiting in front of this star and we still have no idea what it is!" Hippke summarized.

The Kepler telescope is no longer collecting data in the Cygnus region, but Hippke reports that the mystery has captured the imagination of amateur astronomers around the world so thousands of them are pointing their telescopes at Tabby's star, snapping images and sending them to the American Association of Variable Star Observers in hopes of detecting further dips that will shed new light on this celestial mystery.

Explore further: Astronomers say comet fragments best explanation of mysterious dimming star

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1.8 / 5 (14) May 09, 2016
I can see Dyson bubbles, but not spheres, for one reason: novas.
And rings are unstable in plane of rotation.
1 / 5 (11) May 10, 2016
"51 Ophiuchi has a disk of dust and gas that appears to be a young debris disk and is probably a planetary system in the late stages of formation. This system resembles Beta Pictoris, a well known star with a large debris disk, in several ways: spectral type, the presence of an edge-on disk with both gas and dust, and the presence of variable blue-shifted absorption lines suggesting in-falling comets." Wikipedia
or Why there is a ring, an asteroid belt or a disk around the celestial objects?" http://www.svemir...hy-there
1.3 / 5 (16) May 10, 2016
These so called 'scientists' would not accept the idea of an 'alien' if it were standing in front of them. But of course when you are paid to lie, then any twist of the truth, however contorted or convoluted, will do to gull the
1.4 / 5 (11) May 10, 2016
I tried to refer on debris disk as: "Fomalhaut is surrounded by several debris disks." Wikipedia ili https://en.wikipe...k#Origin
There are also intermittent rings as Uranus.
1.3 / 5 (15) May 10, 2016
This is comically like the History Channel's show 'Ancient Aliens', phenomena is claimed or observed and the only explanation that fits the currently accepted Cosmology is to blame it on "aliens". This is extremely laughable and goes to show to what lengths the dogmatic beliefs of the standard theory will be protected, to publish in "peer-review" that ancient aliens did it.

What is needed is a more realistic understanding of the plasma processes that actually occur and not theoretical misgivings.
3.8 / 5 (13) May 10, 2016
A star dimmed 1.5 thousand light years away and we cannot explain it therefore it surely must be a mega alien civilisation construction. Are human beings so afraid of being alone in the Universe that we grasp at the most tenuous belief that we are not? Or is it just too much Star Trek? Quick somebody give me a one star rating before it's too late.
1.8 / 5 (10) May 11, 2016
@someone: Done.
1 / 5 (7) May 12, 2016
The observations point to something very unusual. And so far, there are no good explanations. I think we can all agree to that much, at least?

I agree, with a remark that it is not inexplicably.
1.7 / 5 (7) May 12, 2016
The article headline, and the conclusion drawn by the study's author, are not supported by the study itself. The study shows that Tabby's star hasn't been dimming for the last century, which refutes a claim made by an LSU astronomer. I have no objection to the science or this conclusion. The problem is that this has no bearing at all on the question of whether or not the observed recent dimming is natural or artificial.
Lund and Hippke are as guilty of anti-ET fanaticism as the pro-ET fanatics they wish to refute.
Da Schneib
5 / 5 (7) May 12, 2016
The article headline, ***and the conclusion drawn by the study's author***, are not supported by the study itself. The study shows that Tabby's star hasn't been dimming for the last century, which refutes a claim made by an LSU astronomer. I have no objection to the science or this conclusion.
You'd have been OK if you hadn't said the part set off with asterisks. The conclusion of the study's author was that Tabby's star hasn't been dimming for the last century, which you promptly agreed with. Here's the title of the study: "A statistical analysis of the accuracy of the digitized magnitudes of photometric plates on the time scale of decades with an application to the century-long light curve of KIC 8462852." Look for yourself:

Da Schneib
5 / 5 (6) May 12, 2016
The problem is that this has no bearing at all on the question of whether or not the observed recent dimming is natural or artificial.
Given that half the evidence it was artificial was it had been dimming for a hundred years, I'd say it has a great deal of bearing on whether it's artificial if a study that shows half the evidence it is is incorrect. Massive logic fail here.

Lund and Hippke are as guilty of anti-ET fanaticism as the pro-ET fanatics they wish to refute.
Lund and Hippke came to exactly the same conclusions you agreed with; make up your mind.
4.4 / 5 (5) May 13, 2016
A direct quote from Hippke: "What does this mean for the mystery? Are there no aliens after all? Probably not!" I don't want to sound like I am supporting the ET hypothesis (I favor the idea that it's a sputtering cepheid), but, again, how long the star has been dimming has no bearing at all on whether or not it's caused by aliens. We simply have no evidence either way as to how long it might take an advanced civilization to cause this phenomena, or how it may be done. For instance, if they had a ring for +100,000 years but it's orbital plane doesn't pass Earth, we may have just seen an antenna array go by; you are assuming that construction is current and ongoing. Duration of the dimming does not correlate, and your logic is lacking. I stand by my conclusion that Hippke is going too far with his above statement.
Da Schneib
5 / 5 (7) May 13, 2016
If it doesn't have any bearing when Hippke says it, how come it had bearing when LSU said it?

Simple logical consistency.
3.5 / 5 (11) May 13, 2016
will never be demonstrated by the cranks on here. And I can't believe you'd actually expect it.
1.8 / 5 (5) May 13, 2016
I never said I agreed with LSU's claim either. You've used a straw man argument, not logic.
1 / 5 (4) May 15, 2016
We have all pretty much figured out that the Bush regime lied to the American people concerning weapons of mass destruction in Iraq. Every time some suspected 'WMD' was found, a first report testified to it, and a second report claiming to be a 'study', a 'more thorough analyses' or some other patent leather bull claimed the first one was wrong. That the first reports were consistently right and the second ones just government propaganda and cover up backed up my murder and torture becomes apparent in the light of the consistent refusal by the government to not only not compensate but, diabolically, not even treat conditions whose nature could only be explained by exposure to WMD. For treatment of these unfortunate men and women wounded in war they were not told the truth about would constitute tacit admission of guilt in concealing the presence for WMD for that government's own purposes - maybe using those weapons with malice aforethought & plausible deniability. Same here!!

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