How do You Measure a Black Hole 660 Million Times Larger Than Our Sun?
Scientists at the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have discovered a black hole approximately 660 million times larger than our sun at the center of a galaxy called NGC 1332– 73 million light years away from Earth. So what does this mean and how exactly do you measure a black hole anyways?
The ALMA is the world’s largest astronomical project with the world’s largest telescope. But it’s not a telescope in the way we typically think of one– it’s described more like an antenna. An antenna that looks like a satellite dish and measures submillimeter and millimeter wavelengths via radiation coming from very distant astronomical objects.
But measuring a black hole isn’t easy since it’s essentially a vacuum chamber– so scientists instead have to measure gas or other matter traveling around it and draw up a conclusion that way. Luckily, there is a disk of cold carbon monoxide circling this giant black hole they found– traveling at about 1.1 million miles per hour. So basically this is a giant black hole surrounded by poisonous gas– pretty terrifying!
Anyways, if scientists measure a black hole’s mass incorrectly (which happens a lot), they can’t really draw any conclusions or use the information in a practical way. But the ALMA scientists are pretty confident they were able to measure the mass of the NGC 1332’s black hole correctly which means they can put their findings to practical use somehow. A black hole can form after a star explodes and condenses through gravity; they continue to grow by swallowing gas and surrounding objects. By studying black holes like this one, scientists can learn more about how galaxies form, develop, and evolve.
Scientists think almost every galaxy has a black hole at its center. Which would mean at the center of every galaxy is a giant vacuum. But wouldn’t this mean all the stars and planets are at risk for getting “sucked in”? Not really. In the milky way, for instance, our black hole is thousands of light years away. As long as stars and planets are moving fast enough along their orbits, they aren’t really at risk for getting sucked in.
“This has been a very active area of research for the last 20 years, trying to characterize the masses of black holes at the centers of galaxies … This is a case where new instrumentation has allowed us to make an important new advance in terms of what we can say scientifically,” said Andrew J Baker— a professor working on the ALMA team.
The team at ALMA includes scientists from researchers from all over the world. ALMA is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. The public can even register for free visitor passes on their website!