Gamma Ray Pulsar

This is pretty cool. A new pulsar was discovered that apparently radiates at frequencies typically in the gamma ray regime. Pulsars typically are essentially neutron stars and detected via radio waves. Gamma ray energies are much higher in energy, typically above 100 keV (kilo electron volts) and originate from the nucleus of an atom as it decays from unstable states. What will often happen is that a nucleus will decay via gamma ray decay through a sequence of states until reaching some ground state. Then, in many of unstable nuclei we’ve measured in the lab, it will decay via alpha or beta decay (radioactivity) and become a different element (often also in an excited state from which it will decay). In contrast, X-rays, which are usually lower in energy (ranging from on the order of 100 eV to 120 keV) originate from electrons dropping in energy as they fall into vacant orbitals of the innermost shells of the atom. One of these days, I hope to have enough time to write about some of this in more detail because it is quite fascinating and from studying how a nucleus decays, the path it follows, how it can branch to different paths and how long it remains in a particular state we learn a great deal about the underlying structure of the nucleus.

In any case, from the link:

SYDNEY: About three times a second, a 10,000-year-old stellar corpse sweeps a beam of gamma-rays toward Earth. Discovered by NASA’s Fermi Gamma-ray Space Telescope, this pulsar is the first known to blink in pure gamma rays.

“This is the first example of a new class of pulsars that will give us fundamental insights into how stars work,” says Stanford University’s Peter Michelson, principle investigator for the Large Area Telescope, one of the instruments aboard the orbiting observatory.

The new pulsar – detailed this week in the U.S. journal Science – lies within a supernova remnant known as CTA 1, located about 4,600 light-years away in the constellation Cepheus.

Its lighthouse-like beam sweeps Earth’s way every 316.86 milliseconds. The pulsar, which formed in a supernova explosion about 10,000 years ago, emits 1,000 times the energy of our Sun.

I may have to check out this week’s Science journal as I would love to see what the energy spectrum of this looks like. Be sure to check out the Fermi Gamma-ray Space Telescope (GLAST) that made this intriguing discovery.


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