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
fuse.pha.jhu.edu.