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The newspaper of The Johns Hopkins University June 21, 2004 | Vol. 33 No. 38
Astronomers Detect Molecular Nitrogen Outside Our Solar System

Discovery promises to provide insight into formation of planets

By Lisa De Nike

Using NASA's Far Ultraviolet Spectroscopic Explorer satellite, researchers have for the first time detected molecular nitrogen in interstellar space, giving them their first detailed look into how the universe's fifth most-abundant element behaves in an environment outside the solar system.

This discovery, made by astronomers at Johns Hopkins, promises to enhance understanding not only of the dense regions between the stars but also of the very origins of life on Earth.

"Detecting molecular nitrogen is vital for improved understanding of interstellar chemistry," said David Knauth, a postdoctoral fellow in the Krieger School's Department of Physics and Astronomy and first author of a paper in the June 10 issue of Nature. "And because stars and planets form the interstellar medium, this discovery will lead to an improved understanding of their formation as well."

Nitrogen is the most prevalent element of Earth's atmosphere. Its molecular form, known as N2, consists of two combined nitrogen atoms. A team of researchers led by Knauth and co-author B-G Andersson, a research scientist in Physics and Astronomy, continued investigations of N2 that began in the 1970s with the Copernicus satellite. At least 10,000 times more sensitive than Copernicus, FUSE — a satellite-telescope designed at and operated by Johns Hopkins for NASA — allowed the astronomers to probe the dense interstellar clouds where molecular nitrogen was expected to be a dominant player.

George Sonneborn, FUSE project scientist at NASA Goddard Space Flight Center in Greenbelt, Md., said, "Astronomers have been searching for molecular nitrogen in interstellar clouds for decades. Its discovery by FUSE will greatly improve our knowledge of molecular chemistry in space."

The astronomers faced several challenges along the way, including the fact that they were peering through dusty, dense interstellar clouds that blocked a substantial amount of the star's light. In addition, the researchers confronted a classic Catch-22: Only the brightest stars emitted enough of a signal to allow FUSE to detect molecular nitrogen's presence, but many of those stars were so bright they threatened to damage the satellite's exquisitely sensitive detectors.

HD 124314, a moderately reddened star in the southern constellation of Centaurus, ended up being the first sight line where researchers could verify molecular nitrogen's presence. This discovery is an important step in the complicated process of ascertaining how much molecular nitrogen exists in the interstellar medium and how its presence varies in different environments.

"For nitrogen, most models say that a major part of the element should be in the form of N2, but as we had not been able to measure this molecule, it's been very hard to test whether those models and theories are right or not. The big deal here is that now we have a way to test and constrain those models," Andersson said.

Launched on June 24, 1999, FUSE is a NASA Explorer mission. Goddard manages the Explorers Program for the Office of Space Science at NASA headquarters in Washington, D.C.

For more on the FUSE mission, go to


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