X-ray Emissions Detected From Elusive Cosmic ObjectsOctober 18,
2001 A type of celestial object that has long stumped
astronomers has been found to emit X-rays, thus proving a theory
of how the objects form. Dr. Steven Pravdo of NASA's Jet
Propulsion Laboratory, Pasadena, Calif., and other scientists
have concluded that these objects, called Herbig Haro objects,
are produced by high velocity shocks. Pravdo is the lead author
of a paper published in the Oct. 18 issue of the journal Nature.
Herbig Haro objects are found in regions where new stars are
forming. They are nebulas, or dust and gas clouds. They form
when high-velocity gas emitted from young stars collides with
clouds of interstellar material. The collision heats the gas in
the surrounding nebula to sufficiently high temperatures to
produce X-rays. Observations for the past 20 years showed no
evidence of X-ray emission from these objects, which are named
for astronomers George Herbig and Guillermo Haro. Previous
instruments lacked the resolution and s