ALMA image of the disk of cool hydrogen gas flowing around the supermassive black hole at the center of our galaxy. The colors represent the motion of the gas relative to Earth: the red portion is moving away, so the radio waves detected by ALMA are slightly stretched, or shifted, to the “redder” portion of the spectrum; the blue color represents gas moving toward Earth, so the radio waves are slightly scrunched, or shifted, to the “bluer” portion of the spectrum. Crosshairs indicate location of black hole. Credit: ALMA Photo courtesy of ESO/NAOJ/NRAO), E.M. Murchikova; NRAO/AUI/NSF, S. Dagnello
NEW YORK, June 7 (NNN-AGENCIES) – The center of the Milky Way galaxy is somewhere you wouldn’t want to be. We have it pretty easy here on Earth, orbiting our star and staying out of everyone’s way, but deep within the heart of our galaxy, a monster lurks. It’s a supermassive black hole known as Sagittarius A* (that’s pronounced “A star”, for the record) and while we can’t exactly see it, we know it’s there thanks to decades of scientific observations of our own galaxy as well as many others.
The intense gravitational pull of the black hole draws in just about everything, but nearby debris it hasn’t yet swallowed up orbits in a pattern called an accretion disk. Now, new research reveals that along with dust and super-heated gases, there’s also a ring of comparatively cooler gases hanging out in the neighborhood.
The research, which was published in a new paper in Nature, describes this ring of cool gas that had never before been detected, but “cool” is perhaps not the best term for it. The gas is still incredibly hot at around 18,000 degrees Fahrenheit, but that’s a lot milder than the 18 million degrees Fahrenheit of the bands of hot gas that have been detected near the black hole in the past.
How the various gases — as well as the dust and other debris in the accretion disk — gathered, and the mechanisms at work within the disk, remain a mystery. Going forward, the researchers want to further probe the inner workings of the area around the Milky Way’s black hole and perhaps learn more about how it all works.
“We were the first to image this elusive disk and study its rotation,” Elena Murchikova, lead author of the paper, said in a statement. “We are also probing accretion onto the black hole. This is important because this is our closest supermassive black hole. Even so, we still have no good understanding of how its accretion works. We hope these new ALMA observations will help the black hole give up some of its secrets.”
Artist impression of ring of cool, interstellar gas surrounding the supermassive black hole at the center of the Milky Way. New ALMA observations reveal this structure for the first time. Photo courtesy of NRAO/AUI/NSF; S. Dagnello
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