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View Full Version : Discussion: It's Not a Comet, It's a Pulsar



Fraser
2004-Sep-23, 04:27 PM
SUMMARY: The Chandra X-Ray Observatory took this image of a pulsar surrounded by high-energy particles as it plows through interstellar space. The pulsar is hurtling to the left in this image at a speed of 2.1 million kph (1.3 million mph), and the particles are being blasted back like the tail on a comet. The pulsar is known as "The Mouse", aka G359.23-0.82, and it was discovered in 1987 by radio astronomers using the Very Large Array in New Mexico. Because it's moving so quickly and interacting so visibly with its environment, astronomers have a unique opportunity to understand pulsar magnetic fields, and how they eject material.

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

om@umr.edu
2004-Sep-23, 06:43 PM
Great news, Fraser!

First observations on lonely neutron stars.

http://www.eso.org/outreach/press-rel/pr-2...0/pr-19-00.html (http://www.eso.org/outreach/press-rel/pr-2000/pr-19-00.html)

http://www.arxiv.org/PS_cache/astro-ph/pdf...408/0408356.pdf (http://www.arxiv.org/PS_cache/astro-ph/pdf/0408/0408356.pdf)

Now observations on a fast-moving, fresh one.

The fate of these exotic objects, and the source of the "pulsar wind" are intriguing.

With kind regards,

Oliver
http://www.umr.edu/~om

StarLab
2004-Sep-23, 07:04 PM
So, if the pulsar zoomed by the earth, assuming it caused no damage, would it look like a neutron star? How long would it take to whisk by the earth?

antoniseb
2004-Sep-23, 07:59 PM
Originally posted by StarLab@Sep 23 2004, 07:04 PM
How long would it take to whisk by the earth?
At 1.3 million miles per hour, it would take 22 seconds to cross the diameter of the Earth [even if the Earth was directly in its path]. It would take 11 minutes to travel the distance from Earth to the Moon. It would take about three days to travel the distance from the Sun to the Earth.

TuTone
2004-Sep-23, 08:27 PM
Wow, thats fast! How big are these pulsars? Is it possible to catch one?

Guest
2004-Sep-23, 08:39 PM
Those are weird objects,
there is some odd and wonderful stuff out there in space

:)

om@umr.edu
2004-Sep-23, 08:58 PM
Yes, there are wierd objects "out there in space".

The separation of left and right handed amino acids in meteorites that formed early in the solar system, and in living creatures like you and me, was likely caused by circular polarized light from such an object here, at the birth of the solar system.

See Cronin & Pizzarello, "Enantiometric Excesses in Meteoritic Amino Acids", Science (1997) 275, 951-955.

That object may still be near-by, hidden from view.

With kind regards,

Oliver
http://www.umr.edu/~om

lswinford
2004-Sep-23, 09:15 PM
I remember a story that described how a piece of paper could simply fly up or off a desk or table in a still room. The air molecules are all in random motion anyway, so if enough of them happened to be in an upward random motion at the same time, then there would be the same kind of "lift" that an airplane wing experiences, although only for a few moments.

Pulsars have been described as a spinning neutron star with a hot spot that periodically "flashes" us. Gasseous objects tend to have counter-rotating bands (our atmosphere has the 'prevailing westerlies' and 'prevailing easterlies', the bands of Saturn and Jupiter are also obvious examples, the sun has a faster equatorial spin than the higher latitudes, etc.). What if the spin of this star's hot spot is countered by the opposing spin of the bigger mass of the star? It would be like one of those helicopters with counter-rotational spin mechanisms that allow it to do without the tail rotor. A pulsar jet spin that was synchronized with a massive counter spin would then behave like a big round rocket propelling it through the galaxy.

(Then too, the releasing an untied balloon in a large room and watching whip around, is a picture that also comes into mind. In this case it would be one super-duper 'hot air' balloon :D )

antoniseb
2004-Sep-23, 10:14 PM
Originally posted by TuTone@Sep 23 2004, 08:27 PM
How big are these pulsars? Is it possible to catch one?
The neutron stars are thought to be about 20 kilometers in diameter, and they have more mass than our entire solar system, including the sun. Anything touching the surface of one instantly gets flattened into a layer about one atomic nucleus thick, and the Hydrogen in that layer immediately gets fused into Helium. Catching one would be very difficult.

icusailin
2004-Sep-24, 12:46 AM
:huh: How fast is that compared to the speed of light? Or how may millions of MPH is the speed of light?

anyone know?

antoniseb
2004-Sep-24, 01:56 AM
Originally posted by icusailin@Sep 24 2004, 12:46 AM
How fast is that compared to the speed of light? Or how may millions of MPH is the speed of light?

anyone know?
The speed of light is about 11 million miles a minute, or 670 million miles an hour. This pulsar is moving about 2 tenths of a percent of the speed of light.

zephyr46
2004-Sep-24, 02:26 AM
http://astrosun2.astro.cornell.edu/academics/courses//astro201/images/pulsar.gif

Reminds me of a picture I saw of the Black Widow Pulsar (http://astrosun2.astro.cornell.edu/academics/courses//astro201/puls_bwidow.htm)

http://chandra.harvard.edu/photo/2003/b1957/b1957_comp_med.jpg

B1957+20 (Black Widow Pulsar) (http://chandra.harvard.edu/photo/2003/b1957/) at Chandra.

zephyr46
2004-Sep-24, 02:56 AM
sorry, double posted :rolleyes:

padeen
2004-Sep-24, 03:32 AM
Fascinating story, thanks Fraser.

How do they attain the velocity they have? What event happens to accelate such a massive object away from its original proper motion?

It seems to me they would have to interact with something else, either magnetically or with direct impact. If there is an inital 'explosion', wouldn't that blow matter away uniformly, thereby producing no net velocity vector?

I read elsewhere about the effect of interstellar matter impacting on the surface and causing heating. Would uneven distribution of this matter be sufficient to cause an acceleration?

mark mclellan
2004-Sep-24, 09:31 AM
Whilst i hope we stay @ a safe distance, wouldnt it be fantastic if one of these million mph bodies slammed into an ordinary star "locally". Providing we were at the safe distance just think of the learning/answers that would be available !!!!!

zephyr46
2004-Sep-25, 04:56 AM
Sure mark mclellan, your just in it for the science!

Not to mention the childish pleasure in seeing a star get smashed up :D

I wonder if the pulsar would pass through dragging a tail, leading to planet formation or disipation into asteroids, dust and gas ?

It would be interesting.

The speed and direction of this pulsar seem well known enough, maybe there is some consequence of its travells waiting to be found.

madman
2004-Sep-25, 06:24 AM
the x ray portion seems to have a corkscrew shape.

here's a brightened version of the full field radio image...to show the 55 light year long tail/trail

http://hometown.aol.com.au/Profnim/mrf.jpg

om@umr.edu
2004-Sep-25, 10:58 AM
How does the energy output from this pulsar compare with the energy output of a typical, Sun-like star?

With kind regards,

Oliver
http://www.umr.edu/~om

antoniseb
2004-Sep-25, 12:18 PM
Originally posted by om@umr.edu@Sep 25 2004, 10:58 AM
How does the energy output from this pulsar compare with the energy output of a typical, Sun-like star?
According to this paper the pulsar is currently giving off about 600 times the energy of the sun. This assumes that the pulsar is about 2000 parsecs away. They describe the energy as spin down luminosity, and indicate that the pulsar was formed about 25,000 years ago [very recently on a galactic scale].
Heartbeat of the Mouse (http://adsabs.harvard.edu/cgi-bin/nph-bib_query?2002ApJ...579L..25C)

This more recent paper based on the observations used for the Chandra story posted here was published more recently [July 2004], and assumes that the distance is closer to 5000 parsecs but still reports an output of about 600 times the output of the sun.
THE MOUSE THAT SOARED (http://arxiv.org/PS_cache/astro-ph/pdf/0312/0312362.pdf). It should also be noted that it reports only 1/3 of the lateral velocity [600 kps] that is reported in the article that started this thread [2000 kps]. On this front I'm not sure what to believe.

om@umr.edu
2004-Sep-25, 02:02 PM
Thanks, Anton.

And how do these energy output estimates from this pulsar compare with those from the two isolated neutron stars cited near the start of this thread?

Thanks,

Oliver
http://www.umr.edu/~om

antoniseb
2004-Sep-25, 02:17 PM
Originally posted by om@umr.edu@Sep 25 2004, 02:02 PM
how do these energy output estimates from this pulsar compare with those from the two isolated neutron stars cited near the start of this thread?
I didn't see anything obvious about the luminosity of the first one, except that the page reported its estimated age to be about 100,000 years, which means it should still be radiating more than the sun does. The paper you linked to was pretty old. A newer document indicated that the object was closer than originally thought, and was older and cooler.

The second one was thought to be closer to a million years old and had a bolemetric magnitude a few percent that of the sun.

Note that most lonely neutron stars we've observed are pretty dim, and unless we are fortunate enough to see them superimposed on a dark nebula, or find them close enough to get a direct parallax reading, we have to use less direct ways to guess their distance, and absolute brightness.