New evidence provided by the Gaia satellite places the location of the runaway star J01020100-7122208 in the halo of the Milky Way ( MW ) rather than in the Small Magellanic Cloud as previously thought .
We conduct a reanalysis of the star ’ s physical and kinematic properties , which indicates that the star may be an even more extraordinary find than previously reported .
The star is a 180 Myr old 3-4 M _ { \odot } G5-8 bright giant , with an effective temperature of 4800 \pm 100 K , a metallicity of { Fe / H } = -0.5 , and a luminosity of \log L / L _ { \odot } = 2.70 \pm 0.20 .
A comparison with evolutionary tracks identifies the star as being in a giant or early asymptotic giant branch stage .
The proper motion , combined with the previously known radial velocity , yields a total Galactocentric space velocity of 296 km s ^ { -1 } .
The star is currently located 6.4 kpc below the plane of the Milky Way , but our analysis of its orbit shows it passed through the disk \sim 25 Myr ago .
The star ’ s metallicity and age argue against it being native to the halo , and we suggest that the star was likely ejected from the disk .
We discuss several ejection mechanisms , and conclude that the most likely scenario is ejection by the Milky Way ’ s central black hole based upon our analysis of the star ’ s orbit .
The identification of the large radial velocity of J01020100-7122208 came about as a happenstance of it being seen in projection with the SMC , and we suggest that many similar objects may be revealed in Gaia data .