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Fraser
2005-Sep-01, 06:57 PM
SUMMARY: Astronomers have found a fast moving pulsar on a trajectory that'll take it completely out of the Milky Way. The object, called B1508+55, is located about 7,700 light-years from Earth. The incredibly sharp radio vision of the continent-wide Very Long Baseline Array (VLBA) has tracked this pulsar moving at approximately 1,100 km/s (670 miles/s). By tracking its position back, the astronomers have calculated that it started out in the constellation Cygnus. A powerful nearby supernova explosion probably kicked it into its current trajectory.

View full article (http://www.universetoday.com/am/publish/fastest_pulsar_speeding_out_galaxy.html)

What do you think about this story? Post your comments below.

Greg
2005-Sep-02, 12:12 AM
This is quite fascinating. It shws that we have a long way to go when it comes to understanding the behavior of superdense objects like black holes and pulsars. Yjr current (popular) models cannot account for the velocity of this pulsar's movement out of the galaxy.

AstroStart.nl
2005-Sep-02, 06:38 AM
How long does it take before this pulsar is outside of our galaxy?

antoniseb
2005-Sep-04, 04:42 PM
How long does it take before this pulsar is outside of our galaxy?
As you can imagine, there is no distinct property line that is the boundary of our galaxy, so no precise answer can be given to that question. Perhaps something like "How long till it is further than the most distant known globular cluster?" would make more sense, or perhaps "How long till it's half the distance to M31?"

Concerning mechanisms for getting this object going this fast, there are some that are known. I think the best is that this Pulsar was part of a close binary system, and that this system passed close to a large black hole (perhaps 10-50 solar masses), and that the companion was grabbed by the black hole, and the pulsar was kicked with new excessive velocity. This is similar to the mechanism suggested for the hyper-velocity star seen last year, and apparently coming from the SMBH in the center of the Milky Way.

iron4
2005-Sep-04, 04:46 PM
I wouldn't want to have such a bullet coming towards Earth :S

antoniseb
2005-Sep-04, 05:18 PM
I wouldn't want to have such a bullet coming towards Earth :S
I wouldn't either. Fortunately the odds of this happening are very low.

Maha Vailo
2005-Sep-06, 10:59 AM
Fortunately, there are no intergalactic higway patrolmen out there to give it a speeding ticket. ;)

- Maha "but Officer, I wasn't going that fast!" Vailo

Argos
2005-Sep-06, 02:22 PM
Ive heard people using the expression "scale length" to define the boundaries of the Milky Way. That would be the point where the luminosity of the surrounding stars falls below about 4% of the total luminosity.

johninf
2005-Sep-06, 02:37 PM
"This is the first direct measurement of a neutron star's speed that exceeds 1,000 kilometers per second," said Walter Brisken, an NRAO astronomer. "Most earlier estimates of neutron-star speeds depended on educated guesses about their distances. With this one, we have a precise, direct measurement of the distance, so we can measure the speed directly," Brisken said.
I question the truth of this!
Do any astonomers have"a precise, direct measurement of the distance"?
Any measurement using Hubbles law is doomed to failure.

antoniseb
2005-Sep-06, 04:34 PM
Do any astonomers have"a precise, direct measurement of the distance"? Any measurement using Hubbles law is doomed to failure.
You can be sure that they didn't use "Hubble's Law" to measure the distance to this neutron star. Hubble's Law only works for distances to clusters of galaxies, and this thing in in our galaxy.

suitti
2005-Sep-06, 04:52 PM
Fortunately, there are no intergalactic higway patrolmen out there to give it a speeding ticket.

186,000 miles per second. Its not just a good idea. Its the law.

So, we're exporting black holes now.

I'd be curious what the odds are of importing black holes, ejected from other galaxies. Probably low odds even if galaxies spit out alot of them. Once it leaves the Milky Way, it seems likely that it would be hard to detect, as it would run out of material to eat.

There was a neutron star story a few years back where the neutron star preferentially funneled material towards one pole, giving it a kick in the other direction, allowing it to leave the nursery.

Having a black hole eat the Earth would ruin your whole day. It may be unlikely, but the expected value of the proposition is still pretty bad. Still, the expected value (loss) for meteors striking the Earth is likely worse.

It might be interesting to speculate on what could be done if we knew that a black hole, or neutron star was coming our way in, say, 10,000,000 years. Could we engineer a miss by altering Earth's orbit?

The Bad Astronomer
2005-Sep-06, 08:47 PM
I question the truth of this!
Do any astonomers have"a precise, direct measurement of the distance"?
Any measurement using Hubbles law is doomed to failure.

They used parallax to find the distance, which is extremely precise. While this was not in the press release, it was in the paper published by the scientists, which I read last week.

You cannot just read a press release and judge the science of the announcement. You have to go to the paper itself at least.