A new nova disappeared faster than ever, and an even bigger cosmic catastrophe is coming

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      When a white dwarf steals enough mass, they go nova. But these nova aren’t what we originally thought they were, and the discovery of the fastest nova ever, V1674 Hercules, teaches us more than we could’ve imagined just a few short years ago. A catastrophe is soon coming for this stellar remnant. Here’s what we know about it.

      Once a star runs out of the last of its fuel in its core, its days as a full-fledged star are over. While the most massive stars will have their cores collapse in a catastrophic supernova explosion, most stars will blow off their outer layers gently, leaving the remnant core to contract down, trapping the star’s heat inside, and transitioning into a white dwarf star.

      There’s a limit to how massive a white dwarf can be: about 1.4 times the mass of our Sun. Below that mass threshold, electrons and atomic nuclei in the white dwarf’s core will experience a quantum mechanical pressure from the Pauli Exclusion Principle that holds them up against gravitational collapse. But if the mass ever rises above that threshold, the white dwarf’s core will collapse, creating a runaway nuclear reaction and destroying it entirely in a type Ia supernova explosion. Perhaps paradoxically, the more massive a white dwarf is, the smaller, denser, and hotter it will be. The more massive it is, the closer it is to that critical threshold, where it will experience a catastrophic cataclysm and self-destruct. But, unless it’s going to collide with another white dwarf, its journey toward this destruction is slow and gradual, driven by the accretion of material from a companion star.

      Yes, of course it’s fantastic whenever we break a cosmic record. Finding the fastest nova ever — one that declines from its peak brightness faster than any other ever has — is exciting, but it’s simply representative of incremental progress in this field. One of the cutting-edge fields of astronomy is known as time-domain astronomy, which studies how objects in the Universe vary in properties (like brightness) over time. The faster we can survey large areas of the sky, and monitor how the objects within those areas change over time, the better we can get at finding and identifying objects that burst, flare, or even undergo runaway thermonuclear reactions on shorter and shorter timescales.

      Jesus: Hey, Dad? God: Yes, Son? Jesus: Western civilization followed me home. Can I keep it? God: Certainly not! And put it down this minute--you don't know where it's been! Tom Robbins in Another Roadside Attraction

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