For those interested in the science and less in the fluff: this is notable not because it's "bigger" but because it's the first really good observation that fits with a "pair instability supernova", which is a well developed existing theory but has never been observed.
The basic idea (I'm not a professional here) is that the gamma rays produced in the stellar core provide the bulk of the pressure that holds up the outer star against collapse. But past a certain temperature, the energy of those gamma rays starts preferentially resulting in electron/positron pair production. And the effective pressure per energy of an e-/p+ pair is significantly lower than it is for photons. So the outer core layers start falling downward, picking up energy as they do, and getting hotter. And the still higher temperatures result in gamma production which is even more likely to result in pairs, so the pressure drops still further and the core contracts more, and you get a runaway reaction.
But the runaway is of temperature and not so much density, so what's left after the outer layers of the star all get blown away is a comparatively low density core of extremely hot plasma, which simply diffuses without recollapsing into a neutron star of black hole.
The basic idea (I'm not a professional here) is that the gamma rays produced in the stellar core provide the bulk of the pressure that holds up the outer star against collapse. But past a certain temperature, the energy of those gamma rays starts preferentially resulting in electron/positron pair production. And the effective pressure per energy of an e-/p+ pair is significantly lower than it is for photons. So the outer core layers start falling downward, picking up energy as they do, and getting hotter. And the still higher temperatures result in gamma production which is even more likely to result in pairs, so the pressure drops still further and the core contracts more, and you get a runaway reaction.
But the runaway is of temperature and not so much density, so what's left after the outer layers of the star all get blown away is a comparatively low density core of extremely hot plasma, which simply diffuses without recollapsing into a neutron star of black hole.