Astronomers using a Maunakea observatory have discovered the closest known black hole to Earth.
A team of astronomers using the Gemini North Telescope on Maunakea detected a black hole only 1,600 light-years from Earth, about one-third of the distance away from the previous known closest black hole.
This black hole is located within the Ophiuchus constellation and is estimated to weigh about 10 times the mass of our Sun. It also has a companion: a star that orbits the black hole at roughly the same distance as Earth does the Sun.
“This is the first unambiguous detection of a Sun-like star in a wide orbit around a stellar-mass black hole in our galaxy,” said astrophysicist Kareem El-Badry, lead author of the paper about the discovery, in a statement.
The existence of the black hole was first suggested using data from the European Space Agency’s Gaia spacecraft, which measures the positions and movements of billions of celestial objects to create a detailed 3-D model of space.
That data indicated irregularities in the black hole’s partner star that suggested it was being affected by the gravity of an unseen massive object.
Using Gemini North’s Multi-Object Spectrograph, El-Badry’s team measured the star’s orbit and confirmed that the star was part of a binary system including a star and a “dormant” black hole — a black hole that isn’t currently in the process of consuming matter and is therefore effectively invisible.
This binary system is itself unusual, El-Badry explained.
Any star that could have formed a black hole of such a mass would have likely become a supergiant and consumed its partner star entirely, and theoretical models wherein the partner star survives all require the star to have a much tighter orbit than is currently observed.
“It is interesting that this system is not easily accommodated by standard binary evolution models,” said El-Badry in a statement. “It poses many questions about how this binary system was formed, as well as how many of these dormant black holes there are out there.”
Further observations of the system could shed more light on the formation and development of black holes.
National Science Foundation Gemini Program Officer Martin Still said in a statement that the discovery of a dormant black hole — “uncluttered by the usual hot gas interacting with the black hole” — so close to the Earth could help astronomers discover more dormant black holes.
Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.
