What are the reasons that led CWise J124909+362116.0, a subdwarf star with a cryptic name, to undertake a frantic escape through the Milky Way currently remains a mystery. What we know is that this small star (abbreviated as J1249+36) travels in our galaxy at a speed of two million kilometers per hour. Which in astronomical figures may not mean much, but when we compare it to the speed of the Sun it can startle even the most reckless reader. Our star, and us together with it, barely reaches eight hundred thousand kilometers per hour. More than doubling this speed, J1249+36 is therefore rightfully a pirate of interstellar spaces.
Simulation of a binary system consisting of J1249+36 and a white dwarf that exploded as a supernova. Credit: Adam Makarenko / WM Keck Observatory
The discovery of this bizarre star took place as part of Backyard Worlds: Planet 9, a project involving over eighty thousand citizen volunteers who scrupulously examined masses of images from NASA’s Wise mission, with the aim of reporting any anomalies. The sudden shifts in the images of this small star did not go unnoticed, and so J1249+36 was brought to the attention of astronomers. Who were amazed, and therefore decided to investigate the nature of this object using an infrared spectrum obtained with the Keck telescope in Hawaii. The results of this analysis were presented yesterday by Adam Burgasser, professor of astronomy at the University of California – San Diego, during the 244th meeting of the American Astronomical Society, currently underway in Madison, Wisconsin. Thanks to the spectrum, it was possible to identify the chemical composition of J1249+36 and classify it as an L-class subdwarf star, a category of stars with very low mass and low surface temperatures, which probably constitute the oldest stars in the Milky Way. The combined use of images and spectrum allowed astronomers to map the position and velocity of J1249+36 and predict its orbit with some accuracy. And also his destiny. In fact, outside the Milky Way it seems that the fate of the runaway star will be played out, which constitutes a rare example of a hyperfast star, a family of wandering stars that move so wildly that they overcome the gravitational attraction of the galaxy that hosts them and wander through space intergalactic.
But what happened for a small star to find itself fleeing at crazy speed through sidereal spaces? As we said at the beginning, we don’t know exactly. And yet astronomers have hypothesized two scenarios to explain the crazy motion of J1249+36. According to the first, J1249+36 was in the past in a binary system, in the company of a white dwarf which at a certain point exploded as a supernova due to the accretion of material by J1249+36. The explosion would have given a powerful kick to the small star, giving it the high speed observed. Unfortunately, however, no trace of the explosion and the white dwarf would remain and therefore, although the calculations predict it, there is no compelling evidence in favor of this scenario. The second hypothesis instead sees J1249+36 as an ancient member of a globular cluster, i.e. a system of stars with a spherical shape and which, according to theories, could contain several black holes within itself. In particular, a binary system of black holes would constitute a real catapult, capable of hurling away any star that unfortunately finds itself passing nearby. Even in this case the numbers add up but scientists don’t know what the starting globular cluster could be. A more in-depth chemical analysis could solve the puzzle of the mysterious origin of this object. The heavy elements of the white dwarf could in fact have polluted the atmosphere of J1249+36, just as the globular clusters have characteristic chemical patterns which, if identified in the star, could clarify the stellar system of origin. Burgasser and collaborators hope to soon obtain new, deeper observations of J1249+36 to reveal its origins. In the meantime, let’s enjoy his crazy escape.
Watch the video service on MediaInaf TV:
