Imagine the Universe!
Imagine Home  |   Ask an Astrophysicist  |  
Ask an Astrophysicist

The Question

(Submitted October 30, 2003)

Are some cosmic rays nuclei of iron atoms, and are they from sources in our own galaxy? I read that the ultrahigh-energy cosmic rays that arrive to our atmosphere at 1020 electron volts (eV) or more, are mainly protons? Have any cosmic rays nuclei of iron ever been detected at this range of energy?

The Answer

Thank you for your question. The cosmic rays that have been identified as iron are believed to originate from supernova explosion shock waves in our galaxy.

We don't yet know the composition of the ultra high energy cosmic rays, since they are not directly detected. Although protons seem the likeliest candidate, there is no real physical evidence to support this.

For more on cosmic rays, see

http://helios.gsfc.nasa.gov/cosmic.html.

-- Michael Loewenstein and Amy Fredericks
for "Ask an Astrophysicist"

Previous question
Prev
Main topic
Main
Next question
Next

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

DVD Table of Contents
Educator's Index