Wandering stars pass through our solar system surprisingly often
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 looked at recent sightings of a star cataloged as WISE J072003.20–084651.2.
The star caught Mamajek’s attention because it was about 20 light-years away, but astronomers hadn’t noticed it thanks to its faint nature and tiny apparent motion (or proper motion) in our night sky. .
For him, those two things were a clue. Since it didn’t seem to move much from side to side, the star was probably either moving towards us or away from us at a breathtaking rate. As astronomers continued to talk, Ivanov measured the radial velocity of the star to find out how fast it was moving towards or away from our Sun. Soon they had their answer.
“Within five or 10 minutes we had the first results that this thing came within a parsec [3.26 light-years] of the Sun,” says Mamajek. “He was howling in the solar district.”
The two astronomers and their colleagues will 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 intruder after its initial discoverer, an astronomer named Ralf-Dieter Scholz, who spent a lot of time finding nearby stars.