Eclipsing Pulsar Promises Clues to Crushed Matter

[n2doc]

ScienceDaily (Aug. 17, 2010) — Astronomers using NASA's Rossi X-ray Timing Explorer (RXTE) have found the first fast X-ray pulsar to be eclipsed by its companion star. Further studies of this unique stellar system will shed light on some of the most compressed matter in the universe and test a key prediction of Einstein's relativity theory.


The pulsar is a rapidly spinning neutron star -- the crushed core of a massive star that long ago exploded as a supernova. Neutron stars pack more than the sun's mass into a ball nearly 60,000 times smaller. With estimated sizes between 10 and 15 miles across, a neutron star would just span Manhattan or the District of Columbia.

"It's difficult to establish precise masses for neutron stars, especially toward the higher end of the mass range theory predicts," said Craig Markwardt at NASA's Goddard Space Flight Center in Greenbelt. "As a result, we don't know their internal structure or sizes as well as we'd like. This system takes us a step closer to narrowing that down."

Known as Swift J1749.4-2807 -- J1749 for short -- the system erupted with an X-ray outburst on April 10. During the event, RXTE observed three eclipses, detected X-ray pulses that identified the neutron star as a pulsar, and even recorded pulse variations that indicated the neutron star's orbital motion.


more

http://www.sciencedaily.com/releases/2010/08/100817151447.htm

[derby378]

1. This'll blow your mind...

Some neutron stars also experience "starquakes."

By comparison, the San Francisco earthquake had a magnitude of 8 on the Richter scale. Our own sun occasionally experiences starquakes in its interior that rate 11 on the Richter scale, or approximately 40,000 times the force of the San Francisco quake. If such a quake were to happen in San Francisco, half of the United States and Mexico would likely cease to exist except as a new basin for the Pacific Ocean.

The strongest starquake ever recorded was on a neutron star, and I think it measured 26 on the Richter scale. On the surface of the neutron star, it might have buckled the crust upwards by a millimeter, which is really colossal when you consider how much gravity there is on the surface. If that same 26-magnitude quake were to happen anywhere on Earth, it would split the planet asunder, turning it into a new asteroid field.