The discovery of ‘Scholz’s Star
Around Christmas 2013, Mamajek was visiting a friend and fellow astronomer, Valentin Ivanov, at the offices of the European Southern Observatory in Santiago, Chile. While the two chatted, Ivanov was looking at recent observations of a star cataloged as WISE J072003.20–084651.2.
The star caught Mamajek’s interest because it was just about 20 light-years away, but astronomers hadn’t noticed it thanks to its dim nature and tiny apparent movement (or proper motion) across our night sky.
To him, those two things were a clue. Since it didn’t appear to be moving much side to side, the star was likely moving toward us or away from us at a breathtaking pace. As the astronomers continued talking, Ivanov measured the star’s radial velocity to learn how quickly it was moving toward or away from our Sun. Soon, they had their answer.
“Within five or 10 minutes, we had the initial results that this thing came within a parsec [3.26 light-years] of the Sun,” Mamajek says. “It was screaming through the solar neighborhood.”
The two astronomers and their colleagues would eventually show that it passed even closer than that. In fact, it passed closer to our Sun than any other known star. This status prompted them to name the cosmic trespasser after its initial discoverer, an astronomer named Ralf-Dieter Scholz, who’s devoted significant time to finding nearby stars.