Talk:Magnetar

Known magnetars

Someone (from IP 212.109.130.254, only contribution since 2008) updated the number of known magnetars in the sentence at the beginning of the known magnetars without likewise updating the number of unconfirmed ones. I suspect that some of those unconfirmed ones are now part of the confirmed ones, but without a source, I can't verify. I've tagged it as citation needed; if someone has an appropriate source, could they find any source of suspected ones? Otherwise, the number of unconfirmed ones is now probably erroneous and should be deleted. - Sangrolu (talk) 12:25, 12 April 2011 (UTC)

Sentence

The link in the first sentence to Robert Duncan is pointing to the wrong person of this name.

This appears to have been fixed. - Sangrolu (talk) 12:25, 12 April 2011 (UTC)

Magnetic Field Strength

This article says:

Magnetars are primarily characterised by their extremely powerful magnetic field, which can often reach the order of 10 gigateslas. These magnetic field's are billions of trillions of times stronger than any magnet created by man on Earth

10 gigateslas = 10¹⁰ teslas billions of trillions = an order of 10⁹⁺¹²=10²¹ Implying that man-made magnetic fields have never been more powerful than 10^-11 or 10 picoteslas. This is kind of ridiculous.. moreover this page claims otherwise.

Also, the tesla page claims the strongest magnetars recorded have been 10 terateslas, not gigateslas.

I'm not sure if this last fact is right or not, but I'm going to change "billions of trillions" to "millions" to make this article accurately reflect 10 gigateslas as it claims.

Caliprincess (talk) 05:21, 8 January 2008 (UTC)

[1] says 10¹⁴ Gauss, and 10⁴ gauss = 1 tesla, so that's 10¹⁰ or 10 trillion teslas. [2] and [3] say it's 800 trillion gauss , so that's 80 billion teslas. I suspect someone may have meant "billions or trillions"... Wnt (talk) 02:59, 28 January 2009 (UTC)

Conservation of angular momentum

If the rotation slows, where is the conservation of angular momentum ? In other words, what does it 'push against' in order to slow down ?

Magnetic braking, I searched around here but couldn't find a good article on how it works in stars, how it works in cars though gives an idea on the theory behind it (Electromagnetic brake). This website has some [4] on the stellar version. --Fxer 16:07, July 28, 2005 (UTC)

The angular momentum is ultimately carried away by beams of particles and radiation that are emitted "off-centre" -- a bit like a Katherine wheel in reverse and possibly also by spinning particles and circularly polarised radiation coming from the poles. Stevelinton (talk) 21:00, 21 August 2010 (UTC)

Magnetar and categories

While cleaning up the electromagnetism category, I removed categories from Magnetar as articles are generally supposed to be in their most specific category, and Magnetars is a sub-sub-sub category of stars. I was going to, I had yet to do so, add the Category:Pulsar -- the supercat of Magnetar -- as a subcat of electromagnetic radiation, and Category:Magnetar to Magnetism, as opposed to listing individual articles within electromagnetism. The removal of Stellar Phenomena was a mistake I see now. I'm going to remove the electromagnetism and stars categories from Magnetar, and finish adding the Pular and Magnetars cats . Salsb 13:23, August 16, 2005 (UTC)

The quick and the dead

lethal? If it were so magnetic, wouldn't one be able to stand over it, or wobble up and down between gravity and magnetism? Then wights would have a hard time falling in, though they may be smashed against the walls of their spaceship. lysdexia 12:22, 21 September 2005 (UTC)

At 1000 km from 2 sol mass neutron star gravity is ~15 million gees. Weights will have hard time NOT falling in :)

Cleanup

This article requires a serious cleanup, it looks atrocious. I wish people would stop simply cut&pasting whole web pages into Wikipedia articles without reformatting, reviewing, editing, thinking... --Jquarry 02:11, 14 December 2006 (UTC)

So I have removed the voluminous block of text which was messily cut & pasted from Robert C. Duncan's website. There was already a link to the bloody thing anyway. Sheesh. --Jquarry 02:18, 14 December 2006 (UTC)

Proposed merge from quantum electrodynamic threshold

• Support merge. Not enough information present to be its own article, for the time being. --Christopher Thomas 20:33, 12 April 2007 (UTC)
• Support Clearly the right idea. Shouldn't need much discussion. Gnixon 21:15, 12 April 2007 (UTC)
• Support. At this point, of course. linas 23:47, 12 April 2007 (UTC)
• Support — since I suggested this in the first place, I probably should. Anville 13:34, 13 April 2007 (UTC)

I went ahead with the merge, paraphrasing and rewriting the text because it was a copyvio from Scientific American. Anville 20:00, 13 April 2007 (UTC)

maybe just create only a cover page called wikki, and forget about any content. So we can also forget about people who spend their free time to write something to explain to others. I'm often wondered if you people contribute, or halt contribution. So instead of merging / deleting, just try to write it more easier, readable by young scholars like me. —Preceding unsigned comment added by 82.217.115.69 (talk) 13:24, 15 January 2009 (UTC)

Short Lifetimes

An earlier version of the article stated that SGRs show violent X-ray and gamma-ray flares, and that via these flares these sources eventually exhaust their energy, at which point they become AXPs with X-ray emission only. This statement has been removed for the following reasons:

• It is correct that SGRs are phenomenologically defined by gamma-ray flares, while AXPs have relatively steady X-ray emission. However, recent events suggest that this is somewhat semantic, since when SGRs are not flaring, they look just like AXPs [5], and even the most stable and quiet AXPs have now been seen to emit SGR-like gamma-ray flares.[6]. Thus whether a source is classified as an SGR or an AXP seems to depend on how it was first discovered, rather than by any definitive evolutionary state.

• Observations suggest that the giant flares seen from SGRs do not noticeably drain their energy.[7] It rather seems to be their rapid but on-going braking of their spin period through which they lose energy.[8].

• The available evidence suggests that SGRs do not evolve into AXPs, but rather if anything the reverse sequence occurs.[9].

Tubbs334 22:39, 20 May 2007 (UTC)

• • OK, thanks for clearing this up. But shouldn't the SGR & AXP articles also be updated with this new info? Or perhaps even a merge between these two? Please let me know your thoughs on this. --193.67.80.4 10:56, 22 May 2007 (UTC)

• • • Absolutely - most people think AXPs = SGRs = magnetars, so these should all be one article. Tubbs334 12:47, 22 May 2007 (UTC)

Galaxy Full of Magnetars

The statement, "The Galaxy is thus probably full of dead magnetars", is unsupported and silly. I'm removing it. --Jquarry 05:45, 23 May 2007 (UTC)

That statement has found its way back into the article again. At least it has a reference this time. Listen, even if Duncan's very rough estimate is correct and 30 million magnetars have formed in the Milky Way... hell let's be generous and call it 100 million... That still represents just 0.1% of all stellar bodies in our galaxy. That hardly qualifies as "full of". Unless you think Japan is "full of" Caucasians, or the Earth's crust is "full of" lead. All right, this time I rewrote the statement so it at least sounds logical, even though TBH I'm not at all comfortable with Duncan's reasoning. --Jquarry 05:16, 31 July 2007 (UTC)

research

" "This is a breakthrough because we can now distinguish between surface and magnetospheric phenomena, Guver said. " --Emesee 06:17, 21 September 2007 (UTC)

Formation (percentages unclear)

Question about unclear percentages.

"The supernova might lose 10% of its mass in the explosion [...] —maybe another 80%."

Is that "another 80% of the original mass" is lost (total 90% lost), "80% more than the original 10%" is lost (total 18% lost), or "80% of the remaining mass" is lost (total of 72% lost)? Madmadmadmage (talk) 03:33, 9 December 2007 (UTC)

Relative strength of magnetism vs. gravity

The model of magnetar "starquakes" seems to hint that the magnetic force in magnetars is nearly on a par with gravitational force, to cause massive rearrangements of the crust.

Another [10] says its effect on iron would be 150 million times the Earth's gravitational pull on it... but magnetar matter is perhaps 10¹⁰ times denser than iron, and under a lot more gravitational pull, so it seems like the gravity should utterly predominate?

So to put the question another way: suppose I have two magnetars near one another, stationary, north poles lined up with the spin axes and facing into one another. Is the magnetic force strong enough to make a difference (I assume they don't really bounce, though it's a cute thought), or do they crash into one another pretty much just like it wasn't even there? Wnt (talk) 03:16, 28 January 2009 (UTC)

They rotate to align their poles N-S, and crash together, possibly forming a black hole if there is enough mass. See also Buttered cat paradox. Jehochman ^Talk 13:00, 28 January 2009 (UTC)

I don't know... a spinning magnetar must have quite an angular momentum. Is the magnetic force truly enough to flip one over? Wnt (talk) 19:04, 28 January 2009 (UTC)

Known Magnetars section

The caption under the image under "Known magnetars" says On 27 December, 2004, a burst of gamma rays arrived in our solar system from SGR 1806-20. However, if SGR 1806-20 is 50,000 light-years away, wouldn't it be more accurate to say that it happened in 48,000 B.C.E.? ⋆ QuackOfaThousandSuns (Talk) ⋆ 23:32, 15 November 2009 (UTC)

The quote is technically correct - the burst arrived in 2004. I think 48,000 B.C.E. is meaningless (see Light cone). Wizzy…☎ 12:15, 16 November 2009 (UTC)

There was a sentence about Earth's 'close encounter' with a magnetar giant flare, which I removed. It was some sensational quote from a tv show which really didn't make sense. Alex Deibel —Preceding undated comment added 16:22, 22 May 2013 (UTC)

Neutronium

What is with this statement inside the article?

"The density of a magnetar is such that a thimbleful of its substance, neutronium, would...."

From the neutronium article:

"This term is very rarely used in scientific literature, for two reasons:

There is no universally agreed-upon definition for the term "neutronium". There is considerable uncertainty over the composition of the material in the cores of neutron stars (it could be neutron-degenerate matter, strange matter, quark matter, or a variant or combination of the above). When neutron star core material is presumed to consist mostly of free neutrons, it is typically referred to as neutron-degenerate matter in scientific literature."

So why use neutronium in this article about a neutron star? 89.137.246.65 (talk) 18:17, 30 June 2010 (UTC)Apass

1. Numbered list item

An idea?

If you have a neutron star at the maximum possible mass (short of turning into a black hole), then neutrons can become destabilised so that we have an exchange of particles like in an electric current as they continually break up and reform, so basically an electrical star with protons instead of electrons.(Cyberia3 (talk) 14:17, 1 January 2012 (UTC))

Origins of magnetic field

I am reverting Gark's wholesale removal of the section, and updating it. Not because I originally put it in, but it is relevant. And this user's speculation that the source is unknown while perhaps correct, goes too far to the other side of the issue proclaiming that such fields may not exist despite that inclusion of multiple known magnetars within the article. --Belg4mit (talk) 20:27, 17 January 2012 (UTC)

Section on "The anti-glitch issue"

This needs some rewriting, it makes several references to a scientist called "Kaspi" who is not introduced or referenced in the article. I may do this myself if I get the time.

JackStonePGD (talk) 13:23, 20 August 2013 (UTC)