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Astronomers Solve Magnetic Fields Mystery
An anonymous reader writes "It is a long-standing and unsolved mystery why 80% of all planetary nebulae are not spherical. Theories suggest that magnetic fields play a role in shaping planetary nebulae. A team of astronomers from Germany has now discovered the first direct clue that magnetic fields might indeed create these remarkable shapes. Planetary nebulae are expanding gas shells that are ejected by Sun-like stars at the end of their lifetimes."
If 80% aren't spherical one must ask why the other 20% are NOT.
Is it the magnetic fields also that makes it so in a nebula, a part of it can look more red than another. Let's say in one part of a nebula, the field is stronger and more matter/gas is attracted within that field (if thats how it works.) would that then create all the variations of whichever color that the star creates depending on how and how much gas is spreaded throughout the field?
What I've always wondered is why the orbits of objects as parts of galaxies, solar systems, or even planet/moon systems pretty much share a common plane. And then, even the rotation of the bodies themselves also line up for the most part.
Why don't they all rotate and orbit in any direction they want?
Does gravity just even this all out over time when the objects pass near each other?
Ask astronomers again in a couple of months if they all agree if the morphology of planetary nebulae is solved by the magnetic field alone.
It's cool that they had done POLARIMETRIC measurement of these objects (that's far more dead than UV spectroscopy), however. Especially there is a star like Eta Carinae which seems to have a weaker magnetic field and its bi-polar structure is being driven by its stellar wind alone.
(IANA astromoner, just a physicist)
You have to consider where they got the angular momentum to begin with:
A solar system isn't a bunch of objects that happen to be in the same place. It was originally a gas cloud (perhaps a nebula), which had a little bit of rotation (from whatever source: nova, magnetic fields, or the like). The gas particles, while very dilute from our standards, still interact enough to equalize their (average) velocities. As it collapses, conservation of angular momentum makes it spin faster, until it's dense enough for objects (asteroids, planets, sun) to condense. And since they all condensed out of that same cloud, they're all approximately aligned to the same orbital plane that the original cloud had. (The same explanation applies to why the axes of rotation are also mostly aligned.)
Thus the name 'Crab Nebula'? I see now, thanks for clearing that up.
You sir are a typical dumb idiot, exactly the kind that is destroying the Wikipedia through not deferring to authority despite your ignorance, as per a recent Slashdot story. If you don't know something, why do you feel the need to cast doubt on those who do?
The poster was right, the Crab is a supernova remnant. "The supernova was noted on July 4, 1054 A.D. by Chinese astronomers, and was about four times brighter than Venus, or about mag -6. According to the records, it was visible in daylight for 23 days, and 653 days to the naked eye in the night sky."
If you knew anything at all about astronomy you'd know that you can't conclude anything from the naming of astronomical objects, since they are often named long before their physical nature is known.
Ah, but planetary nebulae have little to do with planets at all. It's a misleading name that got stuck to them because they resembled big planets (or something like that).
Planetary nebulae and supernovae remnants would differ in their origin -- the former from red giants and the latter from supernovae (duh), the size, obviously, shape (explosion cloud vs. ejected atmosphere), and the source of radiation that illuminates the nebulae... but I'm not sure how.
Supernovae remnants would have neutron stars in the middle, but what's in the planetary nebulae? anyone?
Considering everyone reading this article is using a computer with some form of magnetic storage, I'd say he's got a valid point.
Ferromagnetism is way too prolific in magnetic storage, so I'll ignore that and talk about other magnetic effects. Magnetism is directly tied to any inductive element in a circuit, and manifests itself through self and mutual induction. Eg, a signal-carrying wire has a non-zero self inductance based on its geometry.
Design of circuit elements at GHz frequencies requires minimizing inductance (usually by making things as small as possible), or carefully designing inductive elements, which would otherwise attenuate higher-frequencies and thereby limit the component bandwidth. And on the other hand, inductors are very useful in filter design, one fairly common item being an RF choke. But they're usually avoided by microwave or RF engineers. As my old boss said when we were considering using inductors to try to calibrate out a certain nonlinearity in a GHz-bandwidth circuit "Engineers usually avoid inductors because they don't understand them."
So besides magnetic storage, magnetic fields are employed in transformers, as the parent said, which are used in almost all AC-powered devices. Then there are electric motors and dynamos (which would include all automobile starters and alternators). There's also NMR (MRI is merely NMR in a hospital, they took the "nuclear" out of the acronym because they knew people wouldn't go inside a big machine with the word nuclear in it). And they're very common in physics and material science research. I regularly use superconducting magnets (up to 10 Tesla) to probe nano-scale systems.
[I'm not an EE, I'm a physics graduate student. But I did EE research (microwave and optoelectronic) with professional EE's for several years before coming to grad school.]
make world, not war
Yes, actually, if you put it that way, it does make science sound something like religion
GP poster unfortunately got the terms mixed up, which is where the erroneous "it's just a theory" argument gets its foot in the door. A better way to put it would be: "... all we have is hypothesis, evidence, and theory (hypothesis and theory being differentiated only by the reliance on evidence)." And "theory" in the scientific sense is what most people mean when they say "scientific fact," not "educated guess" as it is in everyday speech. (An educated guess in science is, of course, a "hypothesis.")
This is something a lot of people seem to have trouble getting their minds around, but it's critical to an understanding of what science is. Science does not, and cannot, make a claim to Absolute Truth in the way that religion does; if it does, it's no longer science. 2+2=4 is a fact; E=mc^2 is a theory, although one that's extraordinarily well supported by the evidence, and unlikely ever to be disproven -- unlikely, not certain. Everything, including the evidence itself, is subject to revision if someone else comes along and does a better job.
This uncertainty bothers a lot of people, which (I assume, as a nonbeliever) is why they so often seek the comfort of religious absolutes. But it is also the attitude which has produced every bit of technology, from flint spearheads to the internet, that separates us from the apes -- and that technology is what enables us to live our lives as human beings. So, judging by the evidence, it's the way to go.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.