In the constellation Orion, inside a cloud of gas and dust, a young star named PR Ori B suddenly flared up like a stove with fresh wood thrown on the fire. Its brightness rose fivefold. This is a rare event: the star began greedily swallowing gas from its disk, and the disk grew red-hot from friction.
Such outbursts had only been seen in distant stars before, and no one had studied them ahead of time. But PR Ori B turned out to be close by, and old images of it had been preserved. Astronomers compared them with new ones and watched a cold star turn into a blazing disk. New lines appeared in the spectrum, showing that a powerful wind is blowing off the disk.
The most intriguing part: the dust in the disk turned into crystals. Like powdered sugar in hot caramel hardening into candy. Now PR Ori B will become a benchmark for studying such outbursts and will help us understand how planets are born.
PR Ori B is only the second-brightest known FU Orionis-type outburst in the optical, falling roughly one magnitude short of the prototype of the FU Orionis class. What's more, the PR Ori system was already observed as a variable star back in 1888, and complaints about funding for astronomical observations can be found in publications from that era.
Outbursts of young stars like PR Ori B bring to mind the plot of Stanisław Lem's novel Solaris, in which the planet's ocean responds to the star's radiation: here the star's disk responds to the outburst by reprocessing dust and heating up, which alters the chemistry of the future planetary system.