. 24/7 Space News .
EXO LIFE
Natural Causes, Not Aliens, Explain Mystery Star's Behavior
by Staff Writers
Nashville TN (SPX) May 11, 2016


Cascading comets around a distant star. Image courtesy NASA/JPL/Caltech. For a larger version of this image please go here.

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.

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 stars 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.

Research paper: "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," Michael Hippke et al., 2016, to appear in the Astrophysical Journal


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Vanderbilt University
Life Beyond Earth
Lands Beyond Beyond - extra solar planets - news and science






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
EXO LIFE
Are we alone? Setting some limits to our uniqueness
Rochester NY (SPX) Apr 29, 2016
Are humans unique and alone in the vast universe? This question - summed up in the famous Drake equation - has for a half-century been one of the most intractable and uncertain in science. But a new paper shows that the recent discoveries of exoplanets combined with a broader approach to the question makes it possible to assign a new empirically valid probability to whether any other advan ... read more


EXO LIFE
NASA research gives new insights into how the Moon got inked

First rocket made ready for launch at Vostochny spaceport

Supernova iron found on the moon

Russia to shift all Lunar launches to Vostochny Cosmodrome

EXO LIFE
Flying observatory detects atomic oxygen in Martian atmosphere

Clues about Volcanoes Under Ice on Ancient Mars

Second ExoMars mission moves to next launch opportunity in 2020

Although Boiling, Water Does Shape Martian Terrain

EXO LIFE
No more space race for US, rivalry gives way to collaboration

NASA Awards Contract for Aeronautics, Exploration Modeling, Simulation

Michael Watkins Named Next JPL Director

US to move more assets into deep space over next 4 years

EXO LIFE
Long March-7 rocket delivered to launch site

China's space technology extraordinary, impressive says Euro Space Center director

China can meet Chile's satellite needs: ambassador

China launches Kunpeng-1B sounding rocket

EXO LIFE
NASA, Space Station partners announce future mission crew members

New landing date for ESA astronaut Tim Peake

Tim Peake goes roving

Russia delays space crew's return to Earth

EXO LIFE
SpaceX lands rocket's first stage after space launch

SpaceX successfully lands rockets first stage after space launch

Agreement Signed for Airbus Safran Launchers

SpaceX to launch Japanese satellite early Friday

EXO LIFE
Scientists discover potentially habitable planets

MIT compiles list of potential gases to guide search for life on exoplanets

Three potentially habitable worlds found around nearby ultracool dwarf star

Light Echoes Give Clues to Protoplanetary Disk

EXO LIFE
Accelerating complex computer simulations: thinking beyond ones and zeros

Airbus Defence and Space to lead TeSeR, next EU project to clean up space

Army investigating new materials for explosive, propellant use

Engineers create a better way to boil water









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.