Northwestern professor discovers new method for detecting dusty stars

Jillian Sandler, Campus Editor

Northwestern physics and astronomy Prof. Farhad Zadeh has discovered a new method that involves taking photographs with radiowaves to detect dusty clouds and stars.

According to a University news release published Monday, Zadeh made the discovery after noticing dark spots on his radio wave images, something that is unusual given that, due to their long wavelengths, radio waves are not easily absorbed and pass through anything blocking them. He initially thought the dark spots meant nothing, but later determined they were representative of five dusty clouds as found in the center of the galaxy, some of which are located near the black hole Sagitarrius A*.

“When you see these dark stars or clouds in radio wavelength images, it tells you something very interesting,” Zadeh said in the release. “We immediately know there is a cold gas cloud or dusty star mixing with a hot radiative medium and that an interaction is taking place. Knowing details of these clouds is important because the clouds can produce stars and also provide material for the growth of black holes.”

Massive dust and gas outflows surround stars in their early and late evolutionary phases, the release said. Because Zadeh’s technique “provides very good sensitivity of faint dusty features,” it also gives astronomers the ability to determine the size of dusty stars.

The first to discover “radio dark clouds and stars,” Zadeh will present his research findings, which were supported by the National Science Foundation, Tuesday morning at the 221st meeting of the American Astronomical Society in Long Beach, Calif.

— Jillian Sandler