IIt is our galaxy’s strangest star, a flickering globe of light whose sporadic and unpredictable output has baffled astronomers for years. But now the study of Boyajian’s star is being promoted as a research model that could aid in one of the most intriguing of all scientific quests: finding intelligent life on other worlds.
This is the argument that Prof Chris Lintott, astrophysicist from Oxford University, will present at a public lecture – Is it Aliens? The most unusual star in the galaxy – at a Gresham College lecture in Conway Hall, central London, on Monday. Its main target will be Boyajian’s star, sometimes nicknamed Tabby’s star after scientist Tabetha Boyajian, in the constellation Cygnus whose strange dimming and brightening has been the subject of intense study by space probes and observatories in recent years.
“Its behavior is extraordinary,” Lintott told the Observer. “It has quick, random bursts where its brightness drops dramatically and then returns. There is no pattern to it. It flickers as if someone is fiddling with its dimmer switch. There is no other star like this in our galaxy.”
Boyajian’s star was studied in detail by the Kepler space observatory in 2012 when its erratic behavior was first discovered. These observations indicated that a large mass of matter circles the star in tight formation and sporadically blocks its light.
But what was the nature of this great mass of material? Dust rings, disintegrating comets and swarms of asteroids have all been put forward as explanations. However, most attention has gone to the theory, proposed by scientists at Penn State University, that the eclipsing mass may be a large alien megastructure.
Such constructions were proposed by physicist Freeman Dyson, who argued that some alien civilizations might be advanced enough to build large arrays of solar panels around their home stars to capture their heat and light. Dubbed Dyson spheres or swarms by astronomers, the large orbiting structures would be used to power these distant civilizations.
The idea that astronomers had stumbled upon such a structure made headlines around the world—though not for long. Subsequent research has now undermined the idea. “We found that light of different wavelengths is blocked in different amounts: exactly what you would expect from starlight passing through a dust cloud,” Lintott said.
Boyajian’s eclipsing mass is likely a cloud of dust produced when a planet grazed too close to its surface and was torn apart. Nevertheless, the study of the alien object is important because it highlights techniques that are destined to become increasingly important as efforts to identify alien civilizations increase in the coming years, Lintott argues.
As a result, humanity could go radio silent in about 50 years – and this will probably be true for civilizations on other worlds. “The search for extraterrestrial intelligence [Seti] is changing,” he said. “In the past we relied almost exclusively on radio telescopes to detect transmissions from alien civilizations just as our radio and TV transmissions could reveal our presence to them. However, to date we have heard absolutely nothing.”
Nor should we be surprised, argues Lintott. “Humanity has already passed its peak radio wave output because we increasingly use narrow beam communications and fiber optic cables, rather than beaming TV and radio signals into the general environment.”
Humanity could go radio silent in about 50 years as a result – and that would probably be true for civilizations on other worlds, he added. “They will have gone radio silent after a while, like us. So Seti radio telescopes will need to be replenished other ways to search for strangers. We will have to be more creative about what we look for in the data and find unusual things that reveal they are the work of aliens.”
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Searching for Dyson spheres – large planet-sized panels of solar arrays – will be one key route, although other ways to determine the handiwork of aliens will also be needed. An example would be provided by an alien civilization mining asteroids near their home planet, an effort that would create clouds of interplanetary dust that would reveal themselves from their infrared radiation.
“And although aliens do not reveal themselves through radio transmissions, they can easily betray their presence through their radar emissions that they use to guide their aircraft and spacecraft,” Lintott added. “Again, we have to look at these wavelengths for signs of their existence.”
Such work would require analyzes of colossal databases and the story of Boyajian’s star also provides a key demonstration of how this would be done. Its secrets were revealed by an army of citizen scientists, members of the public who collected and analyzed the vast reams of data from the instruments that probed the star, Lintott said.
“It was their combined analyzes of data on Boyajian’s that showed them behaving in a very strange way – and it is very likely that they will be involved in fingering other strange stars in our galaxy in future projects. And you never know, the next time they might get paid dirty.”
