New theory unravels magnetic instability

spaceref.com ^ | 10 Dec 02 | Los Alamos

[RightWhale]

PRESS RELEASE

Date Released: Monday, December 09, 2002

Los Alamos National Laboratory

New theory unravels magnetic instability

Reconnection, the merging of magnetic field lines of opposite polarity near the surface of the sun, Earth and some black holes, is believed to be the root cause of many spectacular astronomical events such as solar flares and coronal mass ejections, but the reason for this is not well understood. Researchers at Los Alamos National Laboratory now have a new theory that may explain the instability and advance the understanding of these phenomena.

Theorists Giovanni Lapenta of Los Alamos National Laboratory's Plasma Theory group and Dana Knoll of the Lab's Fluid Dynamics group presented their findings at the American Geophysical Union meeting in San Francisco at the Moscone Convention Center.

The theory is based on a 19th century mathematical observation called Kelvin-Helmholtz instability. "What we are trying to determine is why magnetic field lines loop out from the surface of the sun, reconnect and then fall back," said Lapenta. "And why these systems, which look very stable, are in fact quite unstable."

According to Lapenta, reconnection rates based on resistivity are orders of magnitude too slow to explain observed coronal reconnections. One possible mechanism that provides fast reconnection rates is known as "driven" reconnection-where external forces drive field lines together in a way that is independent of resistivity. Lapenta and Knoll believe that related work focused on magnetic field line reconnection in Earth's magnetopause has shown that the Kelvin-Helmholtz instability can cause compressive actions that push field lines together and drive reconnection. "We propose that the same mechanism at work in the magnetopause could conceivably be at work in the solar corona and elsewhere," said Lapenta.

In this theory, motion on the visible surface of the sun - the photosphere - leads to twisting deformation waves that move through the chromosphere, a layer of solar atmosphere just above the photosphere, growing larger as they move and emerging with a rapid increase of speed through the sun's corona, or outer atmosphere. This rapid change in speed, or velocity shear, injected into the corona can cause magnetic loops to reconnect, according to Lapenta.

"We have conducted a series of simulations and shown that indeed reconnection can be achieved trough local compression driven by Kelvin- Helmholtz and that the reconnection rate is not sensitive to resistivity," said Lapenta.

From this beginning point, Lapenta hopes to study the processes tied to motion on the surface of the sun to better understand why these "velocity shears" occur and how they move away from the sun and lead to CMEs and other solar events, and to apply this knowledge to better understanding the magnetic fields around the earth and the disc-shaped rotating masses, or accretion discs, that form around some black holes.

[RightWhale]

An application of meteorology to a different fluid: Kelvin eyes, often highly visible, form at the shear boundary. The Giant Red Spot of Jupiter has this appearance, as do hurricanes and galaxies, although they aren't paired like Kelvin eyes often are. It is known that the heat equation can be used to model the dissipation of the magnetic field that surrounds sunspots

[robertpaulsen]

Is this why my refrigerator magnets won't work?

[RightWhale]

What do you mean they don't work? Don't they stick to refrigerators anymore?

[Free the USA]

http://www.freerepublic.com/perl/bump-list

[GovernmentShrinker]

Okay, I asked this question yesterday on the Astronomy Picture of the Day thread, hoping that knowledgeable people there would have an answer. But they didn't respond, so now I'll try you (and any other space-physics folks who might happen along to this thread):

Does anyone here, with professional experience in the field, have any thoughts as to whether it may eventually be feasible to shove Mars into Earth's orbit, thus causing it to acquire a climate similar to Earth's. I don't see much future for humans living in cramped space stations or similar facilities built on the surface of other inhospitable planets, so this seems like the logical direction of human space colonization efforts. I know we're working on ways to shove big asteroids into a path that suits us (i.e. that won't hit us), and most astrophysicists seem to think we'll find a way to do it. So why not planets next? And what would having Mars in Earth's orbit (presumably at the opposite end of the ellipse) have on Earth's gravitational field?

Please ping anyone you know who might be able to give an educated answer to these questions.

[RightWhale]

That's the idea. We will probably move Venus to a Lagrange point in earth's orbit, and move Mercury to orbit Venus, giving it a moon like earth has. Mars could be moved to the other Lagrange point in earth's orbit, but it wouldn't be much of a planet and what would you do for a moon of Mars?

[mrsmith]

MHD is the most difficult and promising area of study.
God bless all who undertake it. They are the scientific pioneers.

Some abstracts from last year's American Physical Society mini-conference on Reconnection: APS

[Dog Gone]

Is your refrigerator logged in?

[Doctor Stochastic]

No.

[robertpaulsen]

I think there's a Kelvin-Helmholtz instability in the compressor. Or in the vegetable bin.

Workin' on it.

[GovernmentShrinker]

Huh?

[GovernmentShrinker]

Why not?

[Sentis]

The Mars problem has long been plauging me and maybe this is the place to address it.

Mars can be Terraformed right NOW


We have the technology to make the planet habitable. I have discussed this with a scientist at NASA a few years ago and he agrees the plan I suggest is possible but will never ever happen becuase it isn't PC. What I suggest is we Nuke the Martian Poles. The Martian poles are made up of 90% Carbon Dioxide with 10%water. What will happen when we nuke the poles is that the Carbon dioxide will be burned producing Carbon ash, Oxygen, and water vapor. The carbon ash will fall to earth (Or should I say Mars) and create a black blanket increasing the albedo of the polar surface keeeping the poles warm releashing the remainder of the CO2. The releashed Oxygen, water vapor, and CO2 will create a Green house affect (Viola, we can create real global warming somewhere if we try really hard). Because there is three times the amount of CO2 in the martian poles than there are gases in Earth's atmosphere the released gases will create a warm world. It will then be ready for the addition of simple plants and animals into its ecosystem. Humans will then also be able to walk the surface with little more than a oxygem system similar to a scuba device.

A moon would also be nice for the red planet becuase a moon helps create a warmer planet due to increased techtonic stresses.

[Doctor Stochastic]

It costs too much in the way of energy. You have to shed Mars's orbital energy and its angular momentum. You asked about feasibility, not miracles.

[Doctor Stochastic]

If we're going the SciFi route, why not just land some genetically engineered bacteria on Mars and let the bacteria do their thing.

[Sentis]

Becuase Nuclear weapons are real and genetically engineered viruses that do what you suggest are scifi at this moment. It's science fiction to believe we can move the planet, Its not science fiction to nuke the bejesus out of the place.

[LibWhacker]

If you look at the formula for orbital period, any object in the same orbit as the earth, but not having the same mass, cannot have the same period. In other words, we'd collide.

[MHGinTN]

The bacteria route isn't sci fi, Doc. They did/do a great job here.

[GovernmentShrinker]

I want to have breathable air so I don't have to walk around with a scuba thingy. Why can't I have it?

[GovernmentShrinker]

Okay. Could we put it in something near enough to Earth's orbit that the climate would be habitable, but not quite IN Earth's orbit? And of course, once we've learned how to move the thing, presumably we could make periodic adjustments if necessary, to avoid collisions.