Magnetic 'force field' shields giant gas cloud during collision with Milky Way

Oct 31, 2013
This is an artist's impression of the Smith Cloud's plunge into the disk of the Milky Way, which it's destined to hit in approximately 30 million years. The cloud, seen in orange and yellow at bottom of the image, is actual data from the Robert C. Byrd Green Bank Telescope (GBT). Credit: Bill Saxton (NRAO/AUI/NSF)

(Phys.org) —Doom may be averted for the Smith Cloud, a gigantic streamer of hydrogen gas that is on a collision course with the Milky Way Galaxy. Astronomers using the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and Robert C. Byrd Green Bank Telescope (GBT) have discovered a magnetic field deep in the cloud's interior, which may protect it during its meteoric plunge into the disk of our Galaxy.

This discovery could help explain how so-called high velocity clouds (HVCs) remain mostly intact during their mergers with the disks of , where they would provide fresh fuel for a new generation of .

Currently, the Smith Cloud is hurtling toward the Milky Way at more than 150 miles per second and is predicted to impact in approximately 30 million years. When it does, astronomers believe, it will set off a spectacular burst of star formation. But first, it has to survive careening through the , or atmosphere, of hot ionized gas surrounding the Milky Way.

"The million-degree upper atmosphere of the Galaxy ought to destroy these hydrogen clouds before they ever reach the disk, where most stars are formed," said Alex Hill, an astronomer at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) and lead author of a paper published in the Astrophysical Journal. "New observations reveal one of these clouds in the process of being shredded, but a protective shields the cloud and may help it survive its plunge."

Many hundreds of HVCs zip around our Galaxy, but their obits seldom correspond to the rotation of the Milky Way. This leads astronomers to believe that HVCs are the left-over building blocks of galaxy formation or the splattered remains of a close galactic encounter billions of years ago.

The Smith Cloud, imaged with the Robert C. Byrd Green Bank Telescope. Credit: Bill Saxton, NRAO/AUI/NSF

Though massive, the gas that makes up HVCs is very tenuous, and computer simulations predict that they lack the necessary heft to survive plunging through the halo and into the disk of the Milky Way.

"We have long had trouble understanding how HVCs reach the Galactic disk," said Hill. "There's good reason to believe that magnetic fields can prevent their 'burning up' in the halo like a meteorite burning up in Earth's atmosphere."

Despite being the best evidence yet for a magnetic field inside an HVC, the origin of the Smith Cloud's field remains a mystery. "The field we observe now is too large to have existed in its current state when the cloud was formed," said Hill. "The field was probably magnified by the cloud's motion through the halo."

Earlier research indicates the Smith Cloud has already survived punching through the disk of our Galaxy once and—at about 8,000 light-years from the disk—is just beginning its re-entry now.

"The Smith Cloud is unique among high-velocity because it is so clearly interacting with and merging with the Milky Way," said Felix J. Lockman, an astronomer at the National Radio Astronomy Observatory (NRAO) in Green Bank, W.Va. "Its comet-like appearance indicates it's already feeling the Milky Way's influence."

Since the Smith Cloud appears to be devoid of stars, the only way to observe it is with exquisitely sensitive radio telescopes, like the GBT, which can detect the faint emission of neutral hydrogen. If it were visible with the naked eye, the Smith Cloud would cover almost as much sky as the constellation Orion.

When the Smith Cloud eventually merges with the Milky Way, it could produce a bright ring of stars similar to the one relatively close to our Sun known as Gould's Belt.

"Our Galaxy is in an incredibly dynamic environment," concludes Hill, "and how it interacts with that environment determines whether stars like the Sun will continue to form."

Explore further: A 'cosmic weather balloon' at the center of the Milky Way

More information: Alex S. Hill, S. A. Mao, Robert A. Benjamin, Felix J. Lockman and Naomi M. McClure-Griffiths. "Magnetized Gas in the Smith High Velocity Cloud". The Astrophysical Journal, Volume 777, Issue 1, p. 55 (2013). DOI: 10.1088/0004-637X/777/1/55 . Also at http://arxiv.org/abs/1309.2553v2

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cantdrive85
1.7 / 5 (21) Oct 31, 2013
Despite being the best evidence yet for a magnetic field inside an HVC, the origin of the Smith Cloud's field remains a mystery.

LOL, it's a mystery for astrophysicists that magnetic fields are created by electricity. And the following statement is apparently as true today as when it was uttered 40+ years ago.

"Students using astrophysical textbooks remain essentially ignorant of even the existence of plasma concepts, despite the fact that some of them have been known for half a century. The conclusion is that astrophysics is too important to be left in the hands of astrophysicists who have gotten their main knowledge from these textbooks. Earthbound and space telescope data must be treated by scientists who are familiar with laboratory and magnetospheric physics and circuit theory, and of course with modern plasma theory." Alfven

Clearly astrophysics is too important to be the realm of idiocy.

24volts
1.3 / 5 (15) Oct 31, 2013
I have to agree with you on this one. I don't see how a random cloud of atoms and molecules are going to create any type of magnetic field as it travels through space.
Lurker2358
1.3 / 5 (14) Oct 31, 2013
Article fails to mention an estimate of the cloud's mass.
Kaymen
1.3 / 5 (13) Nov 01, 2013
Despite being the best evidence yet for a magnetic field inside an HVC, the origin of the Smith Cloud's field remains a mystery.

LOL, it's a mystery for astrophysicists that magnetic fields are created by electricity. And the following statement is apparently as true today as when it was uttered 40+ years ago.

Clearly astrophysics is too important to be the realm of idiocy.



Actually agree with you but I can only give you two stars because you always come across as being extremely arrogant.
yyz
5 / 5 (6) Nov 01, 2013
"Article fails to mention an estimate of the cloud's mass."

A 2008 study estimated the clouds mass at more than a million solar masses: http://arxiv.org/abs/0804.4155

Additionally, the cloud is more than 3x1 kpc in size, located ~3 kpc below the galactic plane, and lies ~12 kpc from the sun.

A preprint of the current paper on the magnetic properties of the Smith HVC is available here: http://arxiv.org/abs/1309.2553
HannesAlfven
1 / 5 (15) Nov 01, 2013
One wonders if there is any case to be made for critical ionization velocity components to the redshifts, but the worldview seems to preclude it before ever considering it ...

Not pretending to know the answer to this, but it does seem unusual to me that nobody even blinks on a paper which deals with ionized gases and magnetic fields that doesn't once include the word "plasma".
cantdrive85
1 / 5 (15) Nov 01, 2013
One wonders if there is any case to be made for critical ionization velocity components to the redshifts, but the worldview seems to preclude it before ever considering it ...

Not pretending to know the answer to this, but it does seem unusual to me that nobody even blinks on a paper which deals with ionized gases and magnetic fields that doesn't once include the word "plasma".

HA, I quoted you above, isn't it obvious? They are completely ignorant of plasma, they prefer their "mathematically elegant" theories of ideal ionized gases that "the plasma itself does not " understand ", how beautiful the theories are and absolutely refuses to obey them", and that we have known for decades to be wrong. Remember astrophysics is the playground of theoreticians who have never seen a plasma in a laboratory. I'm sure you recall saying this, you mentioned these points in your Nobel lecture, you know the one that is largely ignored.
Lurker2358
1.3 / 5 (14) Nov 01, 2013
30 million years is a very long time in human standards or standards of anything now living on Earth or perhaps destined to be living on Earth.

I doubt any gravitational effects would be noticed until near the end of it's approach.

At 1 million solar masses in a 3x1kpc area it's probably close to the same density as our own region inside the Milky Way. If it hit something like a Nebula in the Milky Way, i'd guess it could potentially form an enormous amount of Stars in a relatively short period of time.
Fleetfoot
5 / 5 (3) Nov 07, 2013
Not pretending to know the answer to this,


It's really simple if you read the text:

"Since the Smith Cloud appears to be devoid of stars, the only way to observe it is with exquisitely sensitive radio telescopes, like the GBT, which can detect the faint emission of neutral hydrogen."

The telescope can only observe the neutral hydrogen emissions so that is what is reported.

but it does seem unusual to me that nobody even blinks on a paper which deals with ionized gases and magnetic fields that doesn't once include the word "plasma".


The article states: "But first, it has to survive careening through the halo, or atmosphere, of hot ionized gas surrounding the Milky Way."

If you think the words "ionized gas" mean the same as "plasma" then they have used a synonym. If you think the terms differ, what do you think is the difference between plasma and ionized gas?
cantdrive85
1 / 5 (12) Nov 08, 2013
The telescope can only observe the neutral hydrogen emissions so that is what is reported.

Are you suggesting this neutral hydrogen does not behave like a plasma? How do you account for the "magnetic force field" in this cloud of "gas" devoid of stars?

If you think the words "ionized gas" mean the same as "plasma" then they have used a synonym. If you think the terms differ, what do you think is the difference between plasma and ionized gas?

Still don't get it? There is a fundamental difference to how astrophysicists model the "ionized gas" (ideal gas laws) and the reality of the plasma. As Alfven pointed out over 40 years ago...
"astrophysics is the playground of theoreticians who have never seen a plasma in a laboratory. Many of them still believe in formulae which we know from laboratory experiments to be wrong."
"The reason for this is that several of the basic concepts on which the theories
are founded, are not applicable to the condition prevailing in cosmos. They
are " generally accepted " by most theoreticians, they are developed with the
most sophisticated mathematical methods and it is only the plasma itself
which does not " understand ", how beautiful the theories are and absolutely
refuses to obey them"
Fleetfoot
5 / 5 (2) Nov 08, 2013
The telescope can only observe the neutral hydrogen emissions so that is what is reported.


Are you suggesting this neutral hydrogen does not behave like a plasma?


The cloud is behaving like a brick, just falling into a potential well.

How do you account for the "magnetic force field" in this cloud of "gas" devoid of stars?


I don't have enough information speculate. Now that a field has been detected, specific tests can be done to find out the cause. That is the way science works, unlike your fanatical religion.

If you think the words "ionized gas" mean the same as "plasma" then they have used a synonym. If you think the terms differ, what do you think is the difference between plasma and ionized gas?


Still don't get it?


Clearly you don't.

There is a fundamental difference to how astrophysicists model the "ionized gas" (ideal gas laws) ...


ROFL, sorry CD, ionized gas doesn't behave like an "ideal gas".
cantdrive85
1 / 5 (12) Nov 08, 2013
ROFL, sorry CD, ionized gas doesn't behave like an "ideal gas".

Finally, something we can agree on, sort of. Sadly the "generally accepted" ideal MHD models are just spruced up ideal gas laws.
http://www.damtp....otes.pdf

You know, the ones astrophysicists who have never seen a plasma in a lab still believe in and that we know to be wrong despite constant revision of models due to in situ observation during the space age. There are no birkeland currents or sheets, or cells, double layers, instabilities, or any number of other phenomena observed in plasma discharge in ideal MHD models. The plasma just doesn't understand how beautiful....
Fleetfoot
5 / 5 (2) Nov 09, 2013
ROFL, sorry CD, ionized gas doesn't behave like an "ideal gas".

Finally, something we can agree on, sort of. Sadly the "generally accepted" ideal MHD models are just spruced up ideal gas laws.
http://www.damtp....otes.pdf


The gas still has all the usual mechanical properties of course, unless you think the momentum of a particle is zero in a plasma. EM adds new effects to those so you have to solve for the combination.

There are no birkeland currents or sheets, or cells, double layers, instabilities, or any number of other phenomena observed in plasma discharge in ideal MHD models.


The word "discharge" refers to an external power source (like a battery) being "discharged" THROUGH a plasma. I think you are the one who has never seen a plasma in a lab, those of us who have played with the stuff know this very well.
cantdrive85
1 / 5 (12) Nov 09, 2013
The gas still has all the usual mechanical properties of course, unless you think the momentum of a particle is zero in a plasma. EM adds new effects to those so you have to solve for the combination.

Thank you for proving my point. As stated REPEATEDLY, you believe in models we "know are wrong". Simply adding EM to kinetic gas laws is exactly what Alfven was arguing against and this is what he eluded to when he pointed to the "Thermonuclear crisis". Must read...
http://www.nobelp...ture.pdf

It should be noted men who treat plasma as Alfven did, such as A. Peratt, are tasked with REAL world issues such as nuclear research at LANL for the DOE. As Alfven remarked, "The cosmical plasma physics of today is far less advanced than thermonuclear research physics. It is to some extent the playground for theoreticians who have never seen a plasma in a lab...The astrophysical correspondence to the nuclear crisis has not yet come."
24volts
1 / 5 (9) Nov 09, 2013
All you people voted my comment down but not a single one of you has yet to explain how just a moving cloud of random molecules traveling can generate a electric charge that will create a magnetic field. There has to be a magnet there somewhere to begin with. So where's the big magnet?
Fleetfoot
3.7 / 5 (3) Nov 09, 2013
All you people voted my comment down but not a single one of you has yet to explain how just a moving cloud of random molecules traveling can generate a electric charge that will create a magnetic field. There has to be a magnet there somewhere to begin with. So where's the big magnet?


The simple answer is that the characteristics of the field (strength, direction, structure) haven't been measured yet so nobody knows how it is created. While I have some ideas, they would be useless speculation without the observations to test them.
Fleetfoot
3.7 / 5 (3) Nov 09, 2013
EM adds new effects to those so you have to solve for the combination.


Thank you for proving my point. As stated REPEATEDLY, you believe in models we "know are wrong".


You mean "a few cranks think are wrong". The way it works is that we start with models that incorporate what are known to be significant effects and keep them simple. As discrepancies are found, new underlying physics is added and the new predictions compared to observation. You posted a paper showing how MHD was developed. If you think it wrong, you can propose alternative equations and then model those to see if they produce a better fit.

Simply adding EM to kinetic gas laws is exactly what Alfven was arguing against and this is what he eluded to when he pointed to the "Thermonuclear crisis".


Then he should have proposed an alternative set of equations, if they were more accurate, they would have been used. It was sour grapes because others took his ideas and advanced them, that's science.
cantdrive85
1 / 5 (12) Nov 09, 2013
Without testable predictions you're incompetent to argue the opinions of posters,

You got that right!

You mean "a few cranks think are wrong".

Alfven a crank? Alfven advanced science like few before, and none since.
http://www.plasma...fven.pdf
To be sure, nuclear scientists use Alfven's particle/circuit equations, not the ideal MHD equations of the astrophysicists.

Then he should have proposed an alternative set of equations, if they were more accurate, they would have been used. It was sour grapes because others took his ideas and advanced them

HE DID, AND THEY ARE MUCH, MUCH BETTER! The theoreticians took MHD and ran with it, expounding upon it as you point out. Alfven, who developed MHD, realized the errors via lab research, THEN CHANGED THE MATHS. The sour grapes resides with the mathematicians (and you) who refuse to acknowledge the thermonuclear crisis and the failure of the models to produce the expected outcomes.

Fleetfoot
not rated yet Nov 10, 2013
While I have some ideas, they would be useless speculation without the observations to test them
Without testable predictions you're incompetent to argue the opinions of posters, who have such a predictions already.


Nobody has any predictions on this, it is the first time a field has been detected in this cloud.
cantdrive85
1 / 5 (11) Nov 10, 2013
While I have some ideas, they would be useless speculation without the observations to test them
Without testable predictions you're incompetent to argue the opinions of posters, who have such a predictions already.


Nobody has any predictions on this, it is the first time a field has been detected in this cloud.

One prediction of the EU is that this type of cloud will have a magnetic field, only those who don't understand how to model plasma are surprised by this data.
cantdrive85
1 / 5 (11) Nov 10, 2013
The word "discharge" refers to an external power source (like a battery) being "discharged" THROUGH a plasma. I think you are the one who has never seen a plasma in a lab, those of us who have played with the stuff know this very well.


Here is a primer on plasma discharge;

http://electric-c...utGD.pdf
Fleetfoot
5 / 5 (1) Nov 12, 2013
The word "discharge" refers to an external power source (like a battery) being "discharged" THROUGH a plasma. I think you are the one who has never seen a plasma in a lab, those of us who have played with the stuff know this very well.


Here is a primer on plasma discharge;

http://electric-c...utGD.pdf


Been there, done that. Now explain it without the external current source.

The cloud is isolated in deep space, the electrical equivalent circuit is an isolated capacitor. Within the cloud, you might speculatively get friction-generated heating of the leading edge producing internal ion flow (and hence a magnetic field) but there is no external circuit.
cantdrive85
1 / 5 (8) Nov 12, 2013
Why, that would be contrary to the EU view. Why don't you explain the "standard" theory without DM or DE? Just because we aren't looking for it doesn't mean its not there. The fact that those that are doing the looking are clueless about plasma processes what's the likelihood they would know what they are looking at in the first place? As has been shown, it's difficult to "see" these effects, you've got to look.
cantdrive85
1 / 5 (8) Nov 12, 2013
Within the cloud, you might speculatively get friction-generated heating of the leading edge producing internal ion flow (and hence a magnetic field) but there is no external circuit.[\q]
Once again I appreciate you showing your ignorance of cosmic plasma. What you have claimed is accurate for your theory, but "the plasma doesn't realize how elegant your theories are and absolutely ignores them"... Kinda like you and reputable plasma physicists.
Fleetfoot
5 / 5 (1) Nov 12, 2013
Why, that would be contrary to the EU view.


Because plasma doesn't behave the way you imagine it does. You've only seen plasma globes with RF power sources but astrophysical ionised gas has no equivalent power source attached.
Fleetfoot
not rated yet Nov 12, 2013
Within the cloud, you might speculatively get friction-generated heating of the leading edge producing internal ion flow (and hence a magnetic field) but there is no external circuit.


Once again I appreciate you showing your ignorance of cosmic plasma.


Sorry it was over your head yet again. You have no power source to ionise your imaginary plasma so I dropped you a hint of how you could salvage your fantasy. Shame you know so little you couldn't even figure that out.
cantdrive85
1 / 5 (7) Nov 12, 2013
Sorry it was over your head yet again. You have no power source to ionise your imaginary plasma so I dropped you a hint of how you could salvage your fantasy. Shame you know so little you couldn't even figure that out.

I am becoming ever more dumbfounded by the confusion. Now you're rubbing sticks together to generate magnetic fields, but it's "over my head"!?!? LOL