Astronomers led by Herbert Pablo, who are part of the BRITE project, and their colleagues at the Ritter Observatory have discovered an unusual fall in the light curve of a very massive star that could change our understanding of stars in this class. Iota Orion is a binary star system, and it is clearly visible in the sky with the naked eye, being the brightest star of the Orion constellation sword. Its unique variability has been discovered with the world's smallest astronomical observation satellites known as "nanosatellites."
The luminosity of the star Iota Orion remains relatively stable for 90 percent of the entire time, but then drops sharply, after which a powerful increase in brightness is observed. These unusual changes in brightness are associated with the interaction of two stars moving relative to each other in an elliptical orbit with a period of about 30 days.
Although these two stars spend most of their time apart, they approach each other once during a full orbital revolution so that the distance between them is reduced by up to eight times. At this point in their orbit, the gravitational forces acting between the two stars become so powerful that they instantly distort the outlines of the stars, pulling them towards each other, resulting in unusual changes in the star's light curve. Iota Orion represents the first case in the history of science when this effect is observed for such a massive system (with a mass of about 35 solar masses), which makes it possible to directly determine the masses and radii of the stellar components of the system.
The authors of the work hope that this discovery will spur the interest of researchers in the search for other such systems, which may result in a fundamental shift in our understanding of the evolution of massive stars.
