Talk:Rotation-powered pulsar
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[edit] Wrong talk location, needs split
- This talk page needs to be split off onto Talk:Pulsar
[edit] Proposed merge
This article appears to be mainly about pulsars in general, rather than rotation-powered pulsars. If there is enough information that is specific rotation-powered pulsars, it should remain here, but if, as appears to be the case, there isn't much more than a paragraph of such, I think it should be merged with Pulsar. --—The preceding unsigned comment was added by 86.136.230.255 (talk • contribs) on 01:02, 8 April 2006.
- After reading both articles, I'd suggest just moving most of the "history" section to pulsar. At least half of this article discusses the mechanisms by which radio beams are emitted and different environments rotation-powered pulsars are found in, which is specific enough for its own article as far as I can tell.
- It would also certainly be useful to summarize X-ray, magnetar, and rotation-powered pulsars in the main pulsar article, with "main article: foo" templates, per the usual style for subtopics. If this isn't done by May, I'll probably take a stab at it (busy through the end of April). --Christopher Thomas 05:05, 8 April 2006 (UTC)
- I'd oppose any merge. If you read below you'll see the history of the split and the rationale behind it. I think this rationale is still good, though I agree both articles need a lot of work... they seem, if anything, to have deteriorated in quality over time! --Russell E 01:30, 9 June 2006 (UTC)
[edit] Talk page weirdness
Talk:Pulsar redirects here. That doesn't seem useful. This page is for discussing this article, not Pulsar. --—The preceding unsigned comment was added by 86.136.230.255 (talk • contribs) on 01:02, 8 April 2006.
- As far as I can tell, pulsar was _moved_ to here, talk page and all, when the current version of pulsar was created (to cover non-rotation-powered pulsars). --Christopher Thomas 05:07, 8 April 2006 (UTC)
[edit] Article progress
I know this article still needs lots of work. But I think is an improvement over the previous version.
[edit] Pulsar beam shape
Do pulsars send out a "beam" or a "sheet" of radiation? --AxelBoldt
I'm not completely sure what you mean. If you integrate over several rotations, certainly you will have something like a conical sheet of radiation (or more like a spiral on a conic sheet). Now, if you are asking how large in latitude the emission region is, i'm not sure, as I have not read recent papers on pulsar models. Classic textbooks assume a conical beam. --AN
Yes, I should have been more precise; I meant the latitude size of the emission region. Also, is the emission region at or near the magnetic pole? --Axel
- Two beams. Their breadth and reason depends on the type of pulsar, but they come from the magnetic poles. In accreting pulsars, it's because that's where the infalling material is channeled, so you get hot spots. In other pulsars, it may be due to the emission mechanism (which goes along the field lines). So yes, there are probably lots we don't see. --Andrew 20:12, Feb 10, 2005 (UTC)
[edit] Source of the magnetic field
I have heard that the source of the magnetic field of the pulsar is the spinning of the object. Let me expose my ignorance by asking how a magnetic field can be produced from a star compsed of neutral matter since pulsars are basically a flavor of neutron stars. --Qaz
- See Dynamo theory. It's conductive, but not charged, like ordinary metals. And it's fluid. --Andrew 20:12, Feb 10, 2005 (UTC)
[edit] Neutron star composition
Actually, about 1 in 7 nucleons is a proton and has an electron to go "with it" somewhere. The Fermi level is, after all, finite and it can't push all the electrons down into the protons to make neutrons (and neutrinos) -- Pdn 21:36, Feb 20, 2005 UTC
[edit] Reorganization of pulsar articles
I think there needs to be some reorganization. Possibly, most of the material on this page could be moved to a page titled Radio pulsar. In modern astrophysics usage, there are several different kinds of pulsars, distinguished by their energy source. Spin-powered pulsars (commonly, though less correctly called radio pulsars) are the objects found by Hewish and Bell: neutron stars that are tapping their rotational kinetic energy to power the observed electromagnetic pulses, which are mostly observed in the radio. A second kind of pulsar, found a few years later, is the accretion-powered pulsar (usually called x-ray pulsars). These are neutron stars that are accreting material from companion stars. When the material is channeled onto the surface along the magnetic field it produces hot spots that create the observed pulses when the neutron star rotates. Although both kinds of pulsars are neutron stars, the physics is very different. Finally, magnetars are pulsars powered by ultra-strong magnetic fields trapped in young neutron stars.
It might be possible to write a single entry on pulsars that covers all of these kinds of objects. But I think it would be cleaner to move and slightly rewrite this one, then add two more to cover x-ray pulsars and magnetars. Finally, the pulsar page could get a brief summary and disambiguation pointers to the other pages. If nobody objects or does their own reorganization, I'll give it a try when I get time.
--Thorsett 06:36, 22 Mar 2004 (UTC)
- Ok I made a first attempt at this. The 3 articles already existed, so I just renamed pulsar to rotation-powered pulsar, then made a new pulsar entry outlining the different types. More work is still needed but that's all for now .... Rkundalini 19:11, 30 Nov 2004 (UTC)
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- I have just completed an edit to pulsar in an attempt to streamline things as suggested, in particular removing the text specific to rotation-powered pulsars. I do think it's a good idea to retain a pulsar article covering the broad class, and then branch out on the detailed phenomenology. I dunno - see what you think. I plan to expand on the X-ray pulsar section next... 0utsider 03:13, 3 Mar 2005 (UTC)
[edit] Pulsar-based time standard
Given the discussion of a developing pulsar-based standard of time measurement at Terrestrial Time, and its link to pulsar, oughtn't there be some discussion of this developing standard in the pulsar article? Arkuat 08:35, 2004 Dec 26 (UTC)
- Done, although I messed up by putting current research in the History section ... I think really the whole article needs restructuring but I'll leave that for someone else for now . Rkundalini 00:36, 4 Jan 2005 (UTC)
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- In a similar spirit, I've changed the wikilink at Terrestrial Time (linktext: pulsar) to point to the History section of Rotation-powered pulsar. People will still have to scroll down, but TT used to be sending them to the new pulsar overview article, which didn't include your additions about the work being done on establishing the new timescale (for which I thank you!). Arkuat 05:46, 2005 Jan 8 (UTC)
[edit] Categorization of pulsars
The page is currently somewhat misleading in its categorization: it suggests that X-ray pulsars and rotation-powered pulsars are non-overlapping categories, which is contradicted both by reality and the article at rotation-powered pulsar. --Andrew 20:12, Feb 10, 2005 (UTC)
- Indeed, and the x-ray pulsar entry is very short anyway. How about we rename it to Accretion-powered pulsar, and try to flesh it out somewhat? -- Rkundalini 04:44, 11 Feb 2005 (UTC)
I don't think moving it si the right idea. X-ray pulsars really are a category, but they're not the same category as Accretion-powered pulsars. So I think putting a stub at accretion-powered pulsar is a good idea, to go with the stub for x-ray pulsar. We should, I suppose, also have a stub for radio pulsar. (I say this because a number of articles reference X-ray pulsar with its current meaning.
Another possibility would be to X-ray pulsar into pulsar, with care. --Andrew 05:25, Feb 11, 2005 (UTC)
[edit] Nobel prize
The following text was added by User:Rnt20 and subsequently removed by me:
- Antony Hewish received a 1974 Nobel Prize for developing radio interferometry instrumentation, the Nobel committee giving particular reference to the telescope of his at the Mullard Radio Astronomy Observatory which discovered the first pulsar.
This is inaccurate. Martin Ryle, co-recipient that year, was given the prize for his role in developing interferometry (aperture synthesis in particular). The text pertaining to Antony Hewish does not mention interferometry at all [1]. The reason for the prize was "for his decisive role in the discovery of pulsars" [2]. Also it was not "his telescope", it was MRAO's telescope. If you want to get nit picky, he designed it and was in charge of it but the hard work of building it was shared by several members of the group including Bell, and Bell was responsible for day to day operations and data analysis, including the initial discovery of the pulsar. Perhaps I am being oversensitive but I am also worried that this edit was an attempt to push the POV that Hewish deserved the prize while Bell didn't. --Rkundalini 19:04, 17 Feb 2005 (UTC)
[edit] Non-trivial discovery, and glitching
I'm a bit annoyed that someone took out "to say the least" as trite, because it's my recollection that the regularity was just a few blips followed by a long loss due to scintillation; thus it was true genius to "connect the dots" (or blips) over the missing periods. So I put in "not at all obvious" - hope that's not too trite. -- Pdn 21:40, Feb 20, 2005 UTC
I think that is is worth restoring the explanation I had (or something more accurate if I was sloppy) about interstellar scintillation's having made it hard to recognise the regularity of the pulses (at least across big gaps). That's where Jocelyn Bell's real genius and persistence came in, I think. It's important as a historical note, and also to encourage young people to think (and observe!) independently.
- I agree it was an interesting historical point & apologies for deleting it without explanation; but it is not relevant to the entire class of pulsars for the simple reason that no X-ray pulsars have been detected in radio. So (as you correctly pointed out below) there's no way for them to scintillate. I meant to suggest moving the deleted text to the historical section on radio (rotation-powered) pulsars when I made the change. -- 0utsider 21:24, 4 Mar 2005 (UTC)
Also I believe that the X-ray pulsars are less regular, no? If so, point that out, please. Also they are not subject to scintillation - perhaps worth mentioning.
Otherwise, nice reorganization. One can't let one article get too long.
Pdn 21:34, 3 Mar 2005 (UTC)
- Rotation-powered X-ray puslars are just as regular as rotation-powered radio pulsars. Accretion-powered X-ray pulsars are subject to more glitches, but they're often in binary systems, where they're harder to detect, in spite of their regularity, because of the Doppler shift. --Andrew 09:25, Mar 4, 2005 (UTC)
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- The important point here is the origin of the torque on the neutron star. Rotation powered pulsars are more regular than accretion powered pulsars, because the accretion rate is variable with time and provides a much less steady torque on the neutron star. Furthermore, accreting pulsars can spin up OR down, while rotation-powered pulsars only spin down. The timing noise in accreting pulsars is NOT thought to be due to glitches, although they might contribute, since the first glitch was just detected recently (2004). It is mainly the timing noise from the varying accretion rate that makes glitches hard to detect in accretion-powered pulsars. -- 0utsider 21:24, 4 Mar 2005 (UTC)
[edit] Superconducting vs. superfluid
The article mentions that glitching may be related to a superconducting iterior. I'd thought that these models were for a superfluid interior? --Christopher Thomas 07:48, 3 May 2005 (UTC)
[edit] Nobel prize again
Nobel Prize again: It's not correct that Hulse & Taylor's was the 2nd astronomical Nobel prize. Penzias & Wilson (1978) were radio astronomers (discovery of CMB) and Chandrasekhar and Fowler (1983) got theirs for astronomy. And although Ryle & Hewish are normally cited as the first astronomy Nobellists, arguably Alfvén (1969) got his for his astrophysical contributions (counting solar-terrestrial physics as a branch of astrophysics). -- --86.130.159.86 00:56, 12 Jun 2005 (UTC)
[edit] Names of pulsars
All pulsar names must start with either B or J. It is not sufficient to write PSR 1913+16. The correct name is PSR B1913+16. There are several articles on specific pulsars that need to be fixed. 137.22.224.98 21:25, 14 January 2006 (UTC)
Generally, if it's a B1950 then it's PSR xxxx+/-yy while if it's a J2000, then it's PSR xxxx+-yyyy... 70.55.84.133 12:38, 8 May 2006 (UTC)
