Cosmic Conundrums

 by Max Harvey

(source: NASA)

Despite science's never ending desire to explain as much of the weird and wonderful phenomena that occur around us, there is a great deal that has still been left untouched. Whilst we can predict with pretty decent accuracy the flight of a football using SUVAT equations, or the rate of a chemical reaction through the use of kinetic data, when we turn our eyes to space there seems to be comparatively little that we can comprehend. If you were to actually ask an astrophysicist, they would tell you that we can even only identify about 5% of the universe. This is the 5% that is composed of atoms (or baryonic matter) whilst the other 95% is a mystical mixture of so-called 'dark matter' and 'dark energy'. Now even with only 5 percent of the universe even being visible to us, the universe has a cunning ploy of throwing us the occasional curve ball - a 'scientific riddle' so to speak that doesn't fit with our predictions and baffles our understanding of what really is out there in the rest of the universe.

At this point it is time to introduce what has been dubbed by many scientists in the field as the 'weirdest star system known to man', and one of my personal favourite cosmic conundrums. The star system is called KIC 8462852, or to give it its more practical name, Tabby's star. Tabby's star is fascinating and is of great interest to the space loving community for the simple reason that we are unable to conclusively state why we make the observations that we do about this star system.

To back up just a little bit, I think that it is necessary to have a bit of a deeper look into one of the main techniques that is used for looking at stars in space. The process that I am talking about is known as transit spectroscopy and works on the principle that when objects move between the star we are looking at and our detectors (or in other words they transit the star) they will produce a slight dipping in the intensity of light that we observe coming from the detectors. This is rather intuitive as some of the light is blocked by the transiting object. However, these fluctuations are usually really small and to give an example, the reduction in intensity due to Jupiter transiting the sun is only about 1%. This is important as Jupiter is typically as large as planets get so a 1% reduction in the intensity is seen as pretty large. The reduction in light due to Earth transiting the sun is barely even noticeable on a graph that you might plot as Earth is 11 times smaller in diameter than the gas giant.

From the transit spectroscopy data, a lot can be inferred about the objects orbiting the star at the centre of the system. For starters, a lot can be inferred about the size and shape of the objects: even curves suggest spherical satellites whilst the length of the dimming can be used to infer the size of the object. In conjunction with other data, the orbital period of the orbiting object can also be found. Transit spectroscopy is one of the most effective ways of discovering the makeup of other star systems in the universe.

Back to the point of Tabby's star and its peculiar behaviour: when transit spectroscopy data was collected for Tabby's star, a whole host of peculiar measurements were made. For starters, there were some incredibly large dimming events that occurred, with the maximum dimming being at 20%! Scientists have estimated that if it was a planet producing this dimming event, then it would have to have a surface area 1000 times that of the Earth. This immense dimming was not the only surprise in the data however. The data also showed that this dimming event lasted over a week (whilst most events are only spanning a few hours at most), and in addition to that, the curve produced was asymmetrical, suggesting that the dimming was caused by a non-uniform object. What is even crazier still is that this event was clustered around a similar time to a number of other extreme events that also caused prolonged, elevated, asymmetrical dimming.

From here, Tabby's star caught the eye of the science community for the simple reason that the data wasn't like any other transit spectroscopy data that had ever been collected and there also wasn't an obvious explanation as to what could have possibly caused these abnormal events to occur. Whilst at first, the scientific process of the discoverers was scrutinised to rule out the possibility of systematic or human error, it was quickly found that the explanation must be due to some astrophysical phenomenon.

Next a whole host of researchers put their minds to explaining the mechanism behind these weird observations and naturally a plethora of conflicting theories arose. Whilst these theories spanned form the more sensible, such as dust rings and planetary debris fields, to the more absurd, such as artificial megastructures built by aliens (one example being a Dyson swarm) the key thing is that none of these proposed explanations has been confirmed as the definitive explanation meaning that the mysterious data from Tabby's star will remain a cosmic conundrum.... at least for now.