Deep in the constellations of Lyra, there existed an amazing phenomenon disguising itself as an impossible astronomical body. An object resembling the “upside-down planet” that contradicted the laws of physics has revealed itself to be a historic astronomical discovery. The astronomical phenomenon, discovered 2,600 light-years from Earth, is the first-ever self-lensing binary system, marking the fulfillment of Einstein’s prediction of gravitational lensing in 1936, effectively revolutionizing the study of binary star systems beyond the known universe.
An 88-year-old theory finds its cosmic confirmation in Einstein
Gravitational microlensing has its roots in the brilliant mind of Albert Einstein, who, in 1936, was able to provide the calculation about how much the force of gravity could bend the starlight. For about eight decades, the model was untested with repeating binaries until the discovery of KOI-3278 changed everything, offering the community their “first repeating gravitational lens with a period of 88.18 days.”
The discovery was made by Ethan Kruse, who is currently pursuing his doctorate at the University of Washington, while analyzing data from the Kepler Space Telescope. The result was just the opposite of the dimming effect caused by the passage of planets in front of the star, known as the transit effect, because the system was experiencing “anti-transit,” or brightening due to the phenomenon of gravitational lensing.
The white dwarf serves as the natural magnifying glass
The KOI-3278 system is made up of two star members that are engaged in a gravitational dance, with each star separated by some 43 million miles. The white dwarf star, although Earth-sized, has 200,000 times the mass of the Earth. According to Eric Agol, from the University of Washington, “Gravity curves space and time, so light, on its way to us, is actually bent.”
What makes this discovery a revolution in the study of binary star systems?
Typical microlensing events are observed between unrelated stars, with temporary brightness variations that never recur. But the orbital periods of KOI-3278 provide predictable lensing cycles, occurring every 88 days, which is unprecedented for researchers seeking detailed observation opportunities. The repeatability of gravitational lensing will provide one-time observation capabilities to measure stellar properties accurately.
The result is an improvement over the work conducted by the California Institute of Technology in 2013, which observed the same phenomenon but without the dazzling brightening effect. “The effect in this system is much stronger,” said Agol, who highlighted how having the stars farther apart is beneficial for the lensing effect. The mechanism is strong enough to enable the determination of the mass and temperature of the white dwarf star.
The crucial, subtle element that turns everything around
What makes the announced discovery so special is not only the lensing effect but the potential of the system to find many pairs of the same type within existing datasets. The fact, indeed, that Kruse discovered the system accidentally indicates there are likely many more self-lensing binaries in the Kepler datasets, which had previously been classified among the anomalous ones.
“If everyone’s missed this one, then there could be many more that everyone’s missed as well,” said Kruse.
“The fact that the binary star system is only about 10 million years old, with the two components having just left the birth nursery, will provide valuable insights into stellar formation processes,” said John Grunsfeld, NASA’s associate administrator.
The find confirms the prediction made in 1973 according to stellar evolutionary models, making clear that these configurations are real, indeed existing in the universe. The chase is on! The “upside-down planet” that had made theorists scratch their heads is now the doorway to the future of astronomical observation, realizing that the greatest discoveries often lurk around the most baffling data.
