At OM in the Cosmos

WATCH/LISTEN – THE CELESTIAL TUNING FORK? –

May 11, 2021 – “Voyager 1 is in an interesting region of space that is outside this thing called the heliosphere, which is the protective bubble that encases all the planets in the solar system,” said Stella Ocker, a doctoral student at Cornell University in Ithaca, New York, and one of the authors of the new study. “So, it’s really our only tool for directly sampling the nature of interstellar space.”

Ocker and her colleagues don’t yet know what’s causing the “hum,” but it was measured through ripples of plasma in what’s known as the interstellar medium, the hodgepodge of gas, radiation and particles that make up the space between stars. While it’s not an actual audio signal, the faint drone showed up as vibrations in a narrow frequency bandwidth, Ocker said.

Previously, scientists could only take fleeting measurements of the interstellar medium after periodic but isolated eruptions from the sun, which would unleash shockwaves that coursed through the solar system and beyond. The new findings suggest that by tracking these persistent vibrations in the interstellar medium, it may be possible to tease out specific properties of this environment, such as its density. This, in turn, will help astronomers better understand the mysterious environment beyond the solar system.

“Rather than trying to map the geography around my house based on one or two trees in my yard, this will let me map all the way from my house to the next neighborhood,” said Merav Opher, a professor of astronomy at Boston University who was not involved with the new research.