In 1952, A Group of Three “Stars” Vanished. Astronomers Nonetheless Cannot Discover Them

On July 19, 1952, Palomar Observatory was enterprise a photographic survey of the night time sky. A part of the mission was to take a number of pictures of the identical area of sky, to assist determine issues comparable to asteroids. At round 8:52 that night a photographic plate captured the sunshine of three stars clustered collectively. At a magnitude of 15, they have been fairly shiny within the picture. At 9:45 pm the identical area of sky was captured once more, however this time the three stars have been nowhere to be seen. In lower than an hour that they had utterly vanished.

Stars don’t simply vanish. They will explode, or expertise a quick interval of brightness, however they don’t vanish. And but, the photographic proof was there. The three stars are clearly within the first picture, and clearly not within the second. The belief then is that they should have all of a sudden dimmed, however even that’s onerous to just accept. Later observations discovered no proof of the celebrities to dimmer than magnitude 24. This implies they doubtless dimmed by an element of 10,000 or extra. What might presumably trigger the celebrities to dim by such an astounding quantity so shortly?

One concept is that they don’t seem to be three stars, however one. Maybe a star occurred to brighten for a short while, comparable to a quick radio burst from a magnetar. Whereas this occurred, maybe a stellar-mass black gap handed between it and us, inflicting the flare to gravitationally lens as three pictures for a quick time. The issue with this concept is that such an occasion could be exceedingly uncommon, however different photographic pictures taken throughout the Fifties present related speedy disappearances of a number of stars. In some instances, the celebrities are separated by minutes of arc, which might be tough to supply by gravitational lensing.

One other concept is that they weren’t stars in any respect. The three shiny factors are inside 10 arcseconds of one another. In the event that they have been three particular person objects, then one thing should have triggered their brightening. Given the timespan of about 50 minutes, causality and the pace of sunshine would require they have been not more than 6 AU aside. This implies they must be not more than 2 light-years away. They might have been Oort Cloud objects the place some occasion brought about them to brighten across the identical time. Later observations couldn’t discover them as a result of that they had since drifted on alongside their orbits.

A 3rd concept is that they weren’t objects in any respect. Palomar Observatory isn’t too removed from the New Mexico deserts the place nuclear weapons testing occurred. Radioactive mud from the exams might have contaminated the photographic plates, creating shiny spots on some pictures and never others. Given related vanishings seen on different photographic plates of the Fifties, this appears fairly potential.

At this level, we are able to’t make sure. What we actually want is to seize a couple of of those occasions in fashionable sky surveys, the place we are able to shortly return and make extra observations. For now, it’s a thriller ready to be solved.

Reference: Solano, Enrique, et al. “A shiny triple transient that vanished inside 50 minutes.” arXiv preprint arXiv:2310.09035 (2023).