Stars vanish, or they don’t? Astronomers for thousands of years have accepted that the lights in the sky were fixed and unchanging. Even when it became clear that these lights are physical objects, one of the main assumptions for astrophysicists has been on timescales of millions or billions of years, they go through major changes slowly.
The biggest stars among all the stars which are many times heavier than the sun as they reach the ends of their lives do go through sudden and cataclysmic changes. Their passing is marked by the unmissable cosmic beacon of a supernova explosion, which shines for many months, and may even be visible across hundreds of millions of light-years.
But what if some stars suddenly shine out of visibility. According to known facts about stars, that should be impossible but over the past few years, a group of astronomers has set out to see whether such impossible things happen by comparing data of decades of observations.
According to Beatriz Villarroel of the Nordic Institute for Theoretical Physics Sweden, “VASCO is the Vanishing and Appearing Sources during a Century of Observations project. We’re actually interested in all kinds of vanishing objects, but ideally I’d like to find a star that’s been steady and has been there in the sky for as long as we can remember and as long as we have data for, and one day it just vanishes. And you can point the biggest telescopes in the world at it and still see nothing there.”
Although current understanding suggests that stars change only very slowly, and dramatic disappearances should leave traces behind. The sky is full of stars that change in brightness and pulsate. Beatriz emphasizes that VASCO is about something different. She said they know there are variables, but their timescales tend to be a few years at most. They want to find out something that goes from a completely steady star to just vanishing entirely, this hasn’t been documented, and it’s the kind of discovery that could lead to new physics.