A mysterious cosmic object capable of moving at incredible speeds through the Milky Way, at an impressive rate of over one million kilometres per hour, has been detected by citizen scientists participating in NASA's ‘Backyard Worlds: Planet 9’ project, which aims to search for planets and brown dwarfs beyond Neptune's orbit.
The discovery, despite being written by enthusiastic amateurs, is published in the prestigious Astrophysical Journal Letters.
The mysterious object has a mass similar to that of a small star and was caught in “speed camera” style by NASA's Wise telescope, which mapped the sky in infrared from 2009 to 2011.
But what is this galactic Speedy Gonzales? At the moment, one hypothesis is that it is a brown dwarf, i.e. an object whose mass is between that of a giant planet and a star like the Sun, even though this speed is unheard of even for these bodies.
It is therefore unclear what it is or why it is so fast: perhaps “Speedy” was part of a binary system in which one of the two stars exploded as a supernova, or perhaps it was part of a globular cluster and flew away following an impact with a black hole.
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