Celestia Forums

Thinking about pulsar planets. If the planet orbits the pulsar then at some point during its orbit it must intersect the pulsar beam.

Just wondering on how a planet could survive this, if pulsar beams can rip apart stars, wondered what the relative strengths of the Sun's magnetic field and the Jovian magnetic field are?

A pulsar's beams are very narrow and project from above the magnetic poles. Magnetic poles usually are near the rotational poles. Planets usually are near the equatorial plane of the primary. In other words, they'd usually be close to 90 degrees away from the beams. So the beams of most pulsars probably would miss their planets. What little is left of them after the supernova!

Although there are sure to be lots of charged particles accelerated by the pulsar's magnetic fields, the pulsar beams that we detect primarily consist of photons: long radio waves up through extremely high energy gammas. Photons are neutral. The magnetic fields would be irrelevant so far as the beams are concerned.


The sun's magnetic field averages around 1-2 Gauss in the photosphere, but can be up to 1,000 times that in sunspots. See http://www.noao.edu/noao/noaonews/sep97/node3.html and http://www.adlerplanetarium.org/learn/sun/facts.ssi

The Earth's is about 0.5 Gauss, depending on where you measure it.

Jupiter's magnetic field is about .0001 to 10 KiloGauss depending on where you measure it. See http://hypertextbook.com/facts/1999/AleksandraCzajka.shtml


Does this help?

I thought the reining theory about the Pulsar planets was they re-accreted from debris in the system after the nova blast.

Don Edwards

So Jupiter's magnetic field is stronger than the Sun's?

...

I thought the beam rotated around the axis, that's why the pulsar pulses, so it would sweep out a circle on a plane, and that plane must intersect the planets at some point. Probably it was just a misconception.

Chaos,

I really don't know squat about their relative strengths, but the Web pages I found at first did seem to imply that the peak values of the magnetic fields around Jupiter reached strengths greater than the peak values around the sun. That's not at all the same as how much energy might actually be tied up in their magnetic fields, though. I think the situation is much more complicated than your question would imply.

I found a discussion of the magnetic moments of solar objects which seems to indicate that the Sun's magnetic moment is a lot more than Jupiter's. See http://nedwww.ipac.caltech.edu/level5/March03/Vallee2/Vallee2_3.html

A pulsar's beam comes straight out from its magnetic poles. It seems unlikely that they'll precisely align with the plane of the planetary orbits. One simplified description is at http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html


Don,

As best I can tell, too few pulsar planetary systems have been detected to be able to tell from observation what fraction are remnants and how many are the results of captures. I found one article which said that about 3x10^-4 of them were expected to be remnants, though.

chaos syndrome wrote:I thought the beam rotated around the axis, that's why the pulsar pulses, so it would sweep out a circle on a plane, and that plane must intersect the planets at some point. Probably it was just a misconception.

Chaos, imagine the Earth is a pulsar. Its magnetic poles are at about 80 degrees N and S, so are offset from the rotation axis. If a pulsar jet were blasting out of north Canada at present, it would sweep across all the stars at declination 80 degrees N, lighting each one up briefly and then sweeping past it, only to return 24 hours later (well, 23 hours 56 minutes later if we're going to be picky ). So each star would "see" regular pulses of light coming from the Earth.
But the Moon, with its orbit precessing around in the ecliptic plane, would be unaffected by all the light and radiation at high latitudes, because the pulsar beam is sweeping around in a narrow cone that completely avoids the plane of the Moon's orbit.

Grant