A mysteriously pulsing star just keeps getting more mysterious. Giant clouds of comets? Enormous alien solar panels? A year after its discovery, new evidence still doesn’t add up.
A new paper published to the open source science journal arXiv has scoured all the data recorded by the Kepler space telescope since it was launched in 2009 for any trace of KIC 8462852.
The star — and its strange behaviour — began to be captured by Kepler’s high-precision imaging from 2011.
The study shows it has dimmed overall by a startling degree over the four years it was in the space telescope’s field of view.
This is over and above the huge — but short lived — dips in the star’s light detected in 2011 and 2013.
How a star could dim so fast, yet alone ‘pulse’ in an erratic, non-predictable way, remains a mystery.
DYING LIGHT
If it was a planet, or even a series of planets, the interval would be rhythmical. Measurable. Predictable.
KIC 8462852 (otherwise known as ‘Tabby’s Star’ after its discoverer Tabetha Boyajian) has an erratic glow. What’s more, it’s getting dimmer over time.
These ‘red flags’ were highlighted as early as the 1960s as a possible sign of an immensely advanced alien civilisation.
Such a society would have enormous energy needs in order to span interstellar distances. To meet these needs, one option would be to build a solar-system spanning sphere of solar panels capable of harvesting every photon their home star emits.
The concept was dubbed a “Dyson sphere” after the name of its creator.
NEW LIGHT ON THE MATTER
During the four years Kepler was looking in the general direction of Tabby’s Star, it lost about four per cent of its luminosity.
But not at a constant rate.
In the new study, astronomers Ben Montet and Joshua Simon found the star was initially dimming by about 0.34 per cent per year. A dramatic dip over the course of just 200 days saw its light fall by about 2.5 per cent. Since then, Tabby’s Star has continued to fade at its original rate.
What could be the cause? Perhaps a much closer cloud of dark comets passing between us and the star?
To test this idea, the authors examined 500 stars surrounding KIC 8462852.
None flickered. So whatever the cause may be, it must be closest to Tabby’s Star.
Is it a characteristic of the type of star?
The authors also sifted through the data for another 500 stars, this time for those that matched the size and makeup of Tabby’s Star.
Their brightness remained consistent.
DEFYING EXPLANATION
Since the odd behaviour of Tabby’s Star was announced a year ago, astronomers and astrophysicists the world over have been pouring over the data and pointing their instruments in its direction.
A search for artificial laser light by the Search for Extra Terrestrial Intelligence found nothing. Their reasoning was that there would be plenty of ‘leakage’ of such light from such an alien civilisation.
Then there’s the idea that the flickering and dimming could be caused by an immense cloud of dust or comets slowly falling towards the star itself.
But astronomers say they’d expect such a cloud to show up in infra-red scans of the star and its surrounds. It doesn’t. At least yet.
Some astronomers suggest Tabby’s Star could be spinning (and wobbling) very fast — fast enough to bulge. This would cause the ‘poles’ to become brighter and the equator dimmer. Add a nearby ‘hot Jupiter’ to the mix and you could get similar chaotic light conditions.
But available measurements don’t seem to indicate Tabby’s Star is spinning all that fast.
While Tabby’s Star is no longer inside Kepler’s field of view, Tabetha Boyajian has been funded to use the Las Cumbres Observatory Global Telescope Network to keep an eye on it.
The hope is she and her team will catch it in another of its unexpectedly deep dips. Such data may help explain what is causing it.
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