A runaway star travelling across our galaxy at enormous speed was probably hurled from its cluster by a previously unknown type of black hole.
Researchers from the Keck telescope believe that the high-velocity star, PG 1610+062, was flung across the Milky Way by a “mid-mass black hole” (MMBH).
Keck Observatory data revealed that PG 1610+062, formerly considered an old star with half a solar mass, is actually a surprisingly young star that is ten times more massive. It was ejected from the Galactic disk at almost the escape velocity from the Milky Way.
Objects like MMBHs have been predicted to exist in young stellar clusters in the spiral arms of the Milky Way, but none have been detected yet.
“Now PG1610+062 may provide evidence that MMBHs could indeed exist in our galaxy,” said lead author Andreas Irrgang of the Friedrich-Alexander University of Erlangen-Nuremberg in Germany.
“The race is on to actually find them.”
The team needed spectral data of the star, and its distance and position in the sky made WM Keck Observatory’s Echellette Spectrograph and Imager (ESI) the only tool for the job.
“The collecting area of Keck allowed us to gather enough photons for our object and ESI has exactly the right resolution, which is high enough to resolve all the spectral features,” said co-author Thomas Kupfer of the University of California, Santa Barbara.