Diagram showing the light curve of the star KIC 8462852 during the 19 May 2017 event. The Kepler light curve data from Event 2 from Epoch 2 (black dotted curve) is aligned with the new event, suggesting similar structure. Graphic: David Kipping / Cool Worlds

By Jim Galasyn
21 May 2017

(Desdemona Despair) – The most interesting star in the galaxy just got more interesting. Recall that in October 2015,  The Atlantic reported on KIC 8462852, a star that’s about 1,500 light-years away, and how it was caught exhibiting strange fluctuations in its light emissions. The Atlantic interviewed Yale Postdoc Tabetha Boyajian, the lead author of the now-famous paper, “Planet Hunters X. KIC 8462852 – Where’s the flux?”. She said, “We’d never seen anything like this star. It was really weird. We thought it might be bad data or movement on the spacecraft, but everything checked out.” The Internet hive mind unleashed its imagination, and almost immediately, there was serious speculation that humans had witnessed the first tangible evidence of extraterrestrial intelligence (ETI).

Desdemona became obsessed with the light-curve data and threw in with an off-topic blog post, “Did the Kepler space telescope discover alien megastructures? The mystery of Tabby’s star solved”, which turned out to be the most popular post in the blog’s history, earning Des fifteen minutes of Internet fame. The Boyajian team predicted that given the orbital parameters for hypothetical objects revolving around KIC 8462852, we should see another set of dimming events in May 2017, and Des settled in to wait.

So it was immensely exciting to read Friday’s story in The Atlantic, “The ‘Alien Megastructure’ Star Is Dimming Again”. This time, there are numerous telescopes trained on KIC 8462852, so we can collect much more data in near real-time, as events unfold. Here’s a wrap-up of the situation on Sunday.

The Planet Hunters team successfully predicted the current dimming event

A measure of success for a scientific theory is how well it makes testable predictions, and the WTF paper scores a big hit with one of its predictions:

4.4.3 Aftermath of giant impact in planetary system

A more robust prediction is that future dimming events should occur roughly every 750 days, with one in 2015 April and another in 2017 May. [...] following the prediction in Section 4.4.3, if a collision took place, we should see re-occurring dipping events caused from debris in 2017 May. Unfortunately, the 2015 April event likely went unobserved, as all available photometric archives we checked came up with nothing. [p. 11, p. 13]

This hypothesis explains the dimming as dust and debris from a single, giant collision between planets, similar to the event that formed the Earth-Moon system.

The biggest objection to this hypothesis is the lack of a detectable infra-red signature around the star, which should be present if the dimming is caused by dust.

As of Sunday morning, the dimming event is ongoing

At 10:20am on 21 May 2017, Professor Boyajian tweeted the following data:

the newest light curve for #TabbysStar from LCO 0.4m scopes shows it has a complex shape.

Tabby's star light curve 21 May 2017

So the dimming event continues, which is a surprise if we were expecting a light curve similar to the Day 1540 event. David Kipping helpfully aligned the original Kepler data with the current event (top graph), and with yesterday’s data, they appeared quite similar, but with today’s data, the curves have diverged significantly.

The planetary impact hypothesis gets a boost

Given the successful periodicity prediction and the novel shape of the current event, the “aftermath of giant impact” idea seems to be favored by the data. This theory predicts that the clumps should be expanding and shearing out, so the light curves will change with each transit.

In “Thoughts on Neslušan & Budaj”, Jason Wright discusses another idea, “with a relatively simple but physically motivated model of massive objects (small planets) with very large, extended dust shrouds moving on highly eccentric orbits”.

No spectrum change during the current dimming event

Preliminary spectra show no change during the current dimming event. Researchers at the Liverpool Telescope report: “In an initial analysis we find no difference between the two spectra apart from in features that are attributable to the expected variable telluric absorption features in the Earth's atmosphere.”

This is surprising. If the dimming is due to dust or some other material, there should be some filtering of the light from the star that would reveal the composition of the occulting medium.

Extraterrestrial intelligence is still a viable explanation

Many ideas have been proposed to explain the anomalous light curves from Boyajian's Star. One of the most interesting ETI theories invokes the concept of star lifting, which has been explored by blogger Eduard Heindl, who gets a very good curve fit for a simple model of artificial jets of plasma being pulled from the star:

image

If the dimming is caused by star material, it may be reasonable to expect that the spectra wouldn’t change during a transit event, since the occulting material is the same as the star’s.

Get the latest updates from the scientists:

1 comments :

  1. Anonymous said...

    "Aliens" Why do humans insist on grasping at any straw, that makes their existence seem magical? The earth sucks, nature sucks, the universe sucks. Nothing with any real intelligence would defend this existence. Humans can't tolerate the fact that all of their efforts are in vain. It will all disappear, global warming or not. Previous generations had to worry about the fate of future generations, simply because future generations were an inevitability. That is no longer the case, we can now severely reduce or eliminate ourselves. There is nothing magical about our lives, individually or collectively. We need to put an end to this charade,, not keep defending it, or looking for more "gods" in the form of aliens.  

 

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