I rather like it when scientists come up against something they can’t understand. Tabby’s star is one such conundrum. Its behaviour is – pun intended – out of this world.
One of the ways in which astronomers search for exoplanets is to see if the brightness of a star dips as a planet moves in front of it. Such dips are quite small and quite regular, matching the orbit and size of the exoplanet. Except for Tabby’s star. Hundreds of exoplanets have been discovered by this method, and they all display the nice regularity I’ve described. Except for Tabby’s star.
It’s light dips massively above the 1% a Jupiter sized planet moving in front of it would cause; as much as 15% and 22% have been recorded. The equivalent of something massive enough to obscure half of the surface area of the star. And when it does brightens again, that too is not as expected. Instead of the dip and the rise being the same shape, as current theory says it should, they do not match. Furthermore, even the occurrence of these dips is irregular and difficult to explain. Finally, to add to the mystery, apparently, Tabby’s star has been getting progressively dimmer over the last 100 years or so, (the star was first observed in 1890).
The name “Tabby’s Star” or “Boyajian’s Star” refer to the initial study’s lead author, Tabetha S. Boyajian. The star’s proper nomenclature is KIC 8462852. It didn’t show up in a computer led search for exoplanets and was found by good old fashioned humans. These same humans have come up with many explanations for the behaviour of the star, including of course, aliens at work. But currently, there are no explanations that fit the observations. Although there are a lot of astronomers working on the puzzle and trying to come up with said explanations. Just google “Tabby’s star” and see.
Which I rather like! One little pointer to the fact that we still have a lot to learn about this Universe that we live in!!
It’s remarkable that it is only just over a century before the first flight of an aeroplane, and yet, passing brightly and rapidly overhead was a spaceship carrying six other human beings.
Now there is talk of a Mars colony, a return to the Moon, and even light sails that can cut the journey to another Star to years rather than decades.
But I wondered what human-kind would take into deep space along with them. Greed, hate, intolerance, probably.
But I hoped not.
And then I thought again of the International Space Station that I had seen earlier. It was built by former enemies, now working in cooperation, it carried men and women of different nationalities, people with courage and resolve, prepared to journey through Earth’s atmosphere to get to it and back, let alone to orbit for months in that tiny, fragile tin can. And then to live and work together.
Currently, Scholz’s star is a small, dim red dwarf in the constellation of Monoceros, about 20 light-years away, and now moving away from us. However, about 70,000 years ago, it just grazed the outer reaches of the solar system as it wandered by, accompanied by its brown dwarf companion.
At the closest point in its flyby of the solar system, Scholz’s star would have been a 10th magnitude star – about 50 times fainter than can normally be seen with the naked eye at night. But because it is magnetically active, such stars can “flare” and briefly become thousands of times brighter. So it is possible that Scholz’s star may have been visible to the naked eye by our ancestors 70,000 years ago for minutes or hours at a time during these flaring events.
What would our ancestors have made of this stranger in the heavens? What would we have made of it a thousand years ago if it were passing by us then and not 70,000 years previously?