Talk:Pulsar

message: User:Quarl has suggested merging both accretion powered pulsar and rotation powered pulsar into the general pulsar article on the Astronomy WikiProject talk page. 
:70.51.8.30 05:21, 3 March 2007 (UTC)
thread_title:  Merge [[Radio pulsar]] & [[X-ray pulsar]] into [[Pulsar]] 

message: * We have smaller articles on types of pulsars than either X-ray or radio pulsar, they can be expanded to a fair degree, I would keep them separate and make pulsar into a better overview of pulsars in general. It should overview most types of pulsars, including magnetars, AXP, SGR, short duration GRB, millisecond pulsars, etc. 70.51.8.30 05:27, 3 March 2007 (UTC)
thread_title: Discussion

message: A few examples of things that should probably be in this article.  I've searched the web, and can't find them, so anyone with knowledge, please contribute:
* Radiated spectrum: are they broadband pulses, or narrowband?  A few articles I found suggested narrowband, but none made any general conclusions.
** If they're narrowband, are their peak frequencies scattered all over the spectrum?  Or do pulsars tend to radiate within a small range?  Also, if narrowband, does the peak frequency remain constant over time?
** It may also be instructive to include a plot of intensity vs. frequency for an example pulsar.
* Pulse duration vs. non-radiating period.  The article mentions periods of 1.5ms to 8s, but for how much of that time are they "pulsing"?  I realize that that probably depends on distance from the Earth, so maybe a better metric is the solid angle size of the radiated cone.  Is this about the same size for most pulsars, or does it vary greatly?
* Is there any noticeable precession of the radiation (or rotation) axis?
The above would help describe what a pulsar is/does, not just the history behind their discover.  Thanks to any who can contribute.  —Ryan McDaniel 22:17, 6 July 2007 (UTC)
replies: text: Just flagged this as "attention=yes" on the Physics template; this article needs attention I can't give it.  If this is not a proper use of that attribute, I apologize.  —Ryan McDaniel 21:14, 11 July 2007 (UTC)
thread_title:  More scientific details needed 

message: Shouldn't something be said in this article about how pulsars have been proposed for use as an independent check (or alternative time standard) on terrestrial atomic clocks?  (See Barycentric Coordinate Time.) I would say it myself if I knew how, but I was trying to do some initial research and found nothing in this article; I think there used to be something about this in one of the various articles about various sorts of pulsars, but haven't found it yet, and really, this is the article that I think it ought to be mentioned in.  arkuat (talk) 07:32, 21 February 2008 (UTC)
replies: text: Now some at Pulsar#Precise_clocks and Millisecond pulsar, both refing the same source. - Rod57 (talk) 12:12, 4 April 2015 (UTC)
thread_title: Time standard?

message: Now a new type of pulsar that emits gamma ray radiation has been discovered as well.
http://www.universetoday.com/2008/10/17/fermi-telescope-makes-first-big-discovery-gamma-ray-pulsar/ -- Chupon (talk) 14:30, 21 October 2008 (UTC)
replies: text: — Preceding unsigned comment added by Rod57 (talk • contribs) 08:38, 11 April 2015 (UTC)
thread_title: First gamma-ray only pulsar

message: For X years ago, where X is at most 50 years, only a couple of pulsars where visually identified. What's the current status? I.e.: could the article relate to visual identification. I know for sure that the Crab pulsar is visually identified, but more? ... said: Rursus (mbork³) 13:00, 14 August 2009 (UTC)
replies: text: Maybe, we should consider merging the too small Optical pulsar into this article? ... said: Rursus (mbork³) 13:07, 14 August 2009 (UTC)
thread_title: Visual?

message: What neither this article or "Neutron Stars" makes clear is WHAT PROPORTION of neutron stars are pulsars. Reading the ambiguous text on the "lighthouse effect", readers could well conclude that ALL neutron stars are pulsars, and that we don't see more of them pulse only because the beam from most of them does not sweep across the Earth. It amazes me how such obvious questions do not cross the minds of those who write this stuff. I gather that most neutron stars are NOT pulsars, though why some are and some are not finds no answer here. The following quote from WP article "Neutron Star" is about as close as we get.
If the surface temperature exceeds 106 kelvin (as in the case of a young pulsar), the surface should be fluid instead of the solid phase observed in cooler neutron stars (temperature <106 kelvin)[10]. Myles325a (talk) 04:37, 26 September 2009 (UTC)
replies: text:  "106 kelvin" = 10^6 kelvin ? - Rod57 (talk) 13:55, 31 May 2022 (UTC)

text: This is a difficult question to answer properly, as there are many neutron stars observed by other means (e.g. X-rays), which we (scientists) don't know if they are radio pulsars or not.  And there are other objects which appear to be radio pulsars at some times, and not to be radio pulsars at other times--some are magnetars (http://adsabs.harvard.edu/abs/2006Natur.442..892C), and some intermittently accrete in binary systems (http://adsabs.harvard.edu/abs/2009Sci...324.1411A).   However, one can make a simple estimate; as the average pulsar lasts probably ~30 million years (see http://www.cv.nrao.edu/course/astr534/Pulsars.html, Fig. 4), but neutron stars have been formed throughout the age of the universe (13.6 billion years), thus of order ~500 times more neutron stars must exist than pulsars--probably more than ~1000 times more, as the star formation rate was higher earlier in our Galaxy's history.  The fraction of neutron stars that are spun up in binary systems to become millisecond radio pulsars is quite small, but they radiate as pulsars for billions of years; the numbers for millisecond pulsars may be similar to the number of pulsars, though that isn't certain.  Craigheinke (talk) 19:05, 29 November 2009 (UTC)
thread_title:  how many neutron stars are pulsars? 

message: I can't find any evidence of X-ray emission changes in CTA 1, either in the referenced Atkinson article, or in the science literature  (see http://www.iop.org/EJ/article/0004-637X/612/1/398/60375.html).  So I took that out, and rephrased its notability to be its pulsations only being seen in the gamma-ray.  There's a good chance that X-ray pulsations will be detected in the near future, since the existing X-ray pulsation constraints are weak and further observations are being performed. Craigheinke (talk) 19:14, 29 November 2009 (UTC)
thread_title:  CTA 1 

message: Some wiki-styled sources refer to the pulsar as being 280 light years away, however http://chandra.harvard.edu/photo/2009/j0108/ gives an estimate of 770 ly. Can someone doublecheck?  —Preceding unsigned comment added by 216.239.79.193 (talk) 04:40, 1 December 2009 (UTC)
replies: text: The recent VLBI parallax measurements by Deller et al give a distance of 240 parsecs, which is about 770 ly. However, the original discovery paper by Tauris et al gives a distance of < 100 parsecs, which is presumably the source of the 280 lightyear figure. Scog (talk) 08:44, 8 December 2009 (UTC)
thread_title:  PSR J0108-1431 contradiction 

message: This article has no explanation of what the pulsar wind is, and pulsar wind simply redirects back here. 99.55.136.210 (talk) 04:47, 1 March 2010 (UTC)
replies: text: I was going to make this exact same comment. Who decided to redirect Pulsar Wind to this article without actually giving an explanation of it? Very frustrating! --InvaderXan (talk) 13:22, 15 July 2010 (UTC)

text: While this is an ancient section, the objection is still accurate. There is a link to pulsar wind, but no article save the redirect to the pulsar article. There is also no mention of what a pulsar wind is, its mechanisms of operation, etc. If there is no objection, I'll remove the link to the non-existent article.Wzrd1 (talk) 00:52, 9 November 2013 (UTC)
replies: text: Even better, I'll change the link to go to the article Pulsar wind nebula, which explains pulsar wind briefly.Wzrd1 (talk) 04:28, 10 November 2013 (UTC)
thread_title:  Pulsar wind? 

message: How is it possible for Neutron Stars (which are supposedly electrically neutral) to have charged particles around them and emit radio pulses? Shouldn't the super strong gravitational field pull the particles into the star and neutralize them? I know that everything with a surface temperature different from it's immediate environment radiates; what is a pulsar's surface temperature?JeepAssembler (talk) 20:48, 7 August 2010 (UTC)
replies: text: Well, if you look at the equation of state of a neutron star, you see that the star isn't simply a solid ball of neutrons. Yes, the inside of the star is made up entirely of neutrons (most likely in a superfluid state), but the crust of the star is not. At the surface of the star it is mostly composed of iron (Fe). As you move into the star, the ever increasing pressure pushes more and more of the electrons into the nuclei of the atoms, thus forming increasingly absurdly heavy isotopes of the 'lighter' element, until the pressure becomes so high that all the electrons are pushed into the nuclei, and the entire mass becomes homogeneously neutron material. In short, this means that at the surface of the neutron star there are atoms with magnetically charged components, which can be acted on by the extremely strong induced electric field (specifically the component of it perpendicular to the magnetic field). This electric field is strong enough to pull charged particles out of the surface (against the strong gravitational field), and accelerate them to very high speeds in a comparatively short distance (as shown by Goldreich & Julian (1969)). The models of how these particles are accelerated etc., predict that their speeds will be ultra-relativistic (i.e., super close to the speed of light) after only a few millimeters of motion (as little as 3mm or so). This doesn't happen everywhere, however, only over the polar regions of the pulsars (magnetic poles, not rotational poles). The magnetosphere of the pulsar is divided into two regions, the closed region and the open region. The boundary between these two regions is delimited by the last field line that closes inside the so-called light cylinder. Basically any field line closer to the magnetic pole than this line would have to close at a distance farther from the pulsar than the distance at which something would need to move at the speed of light just to co-rotate with the pulsar (like a geostationary satellite staying over a certain spot on the Earth's surface). Because all the field lines in the closed region are, well, closed inside the light cylinder, no charged particles can escape this region, and the charged particle plasma nullifies the accelerating electric field in this region. Thus, the closed region consists of a cloud of charged particles co-rotating with the neutron star. In the open region the particles can escape through the light cylinder, meaning that there is a continual stream of charged particles flowing out from the neutron star surface at the magnetic polar caps. It's radiation from these particles that we see, and it is this geometry (open and closed regions) which is responsible for the beamed-ness of the emission. About the surface temperature of pulsars: Well this is a slightly more involved topic, but the basic fact is that the polar caps are much hotter than the rest of the neutron stars surface, and are the sources of some of the radiation we see in x-ray pulsars (the so-called thermal x-ray component). I'm not going to describe how the heating actually happens, because that's way more detail than I want to go into here, but what I've put down should be interesting enough. Tjips (talk) 13:37, 19 November 2012 (UTC)

text: That's all we have until we can go out there and visit the things up close. And by then, expect to have your cherished assumptions dashed asunder. Kortoso (talk) 21:42, 21 October 2014 (UTC)
replies: text:  @Cigarshaped maybe some Pulsar uses an oscillator to flash. But you have to explain where the energy for the signals comes, and if you use gravitational energy you have to explain how the frequecy decreases with radius. And you have to bring other references from someone seriously exploring this possibility, because repeating "this or that is mostly unlikely", as in your holoscience page, doesn't mean serious science <I>per se</I> 194.174.76.21 (talk) 19:19, 28 February 2017 (UTC)
thread_title:  How Is It Possible? 

message: Please tell what the life cycle of a pulsar is.  Article tells how they form.  Since they keep giving off energy, what's the long term fate of them?  —Preceding unsigned comment added by 72.83.70.206 (talk) 22:43, 1 May 2011 (UTC)
replies: text: It depends on the system; binaries will obviously evolve differently from lone pulsars.  However, for all cases, they will eventually cool off (i.e. run out of energy) since they are no longer engaged in nuclear fusion, and as they do their emitted energy drops over time until it becomes undetectable. siafu (talk) 23:34, 1 May 2011 (UTC)
thread_title:  Pulsar life history 

message: This article could be improved by adding a section explaining Pulsar Winds. The only article with information regarding it, is the 'pulsar wind nebula' page. A pulsar wind is a significant aspect of the Pulsars, hence adding a section on it should be prioritized on further expansions of the article. 
Pulsar wind nebula - page:  http://en.wikipedia.org/wiki/Pulsar_wind_nebula  — Preceding unsigned comment added by Fredrikdn (talk • contribs) 14:12, 29 July 2012 (UTC)
thread_title:  Pulsar Wind 

message: 'The scientists identified a pulsar that is able to dramatically change the way in which it shines. In just a few seconds, the star can quiet its radio waves while at the same time it makes its X-ray emissions much brighter. The research “challenges all proposed pulsar emission theories,” the team writes in the Jan. 25 edition of the journal Science and reopens a decades-old debate about how these stars work." '
From http://www.sciencedaily.com/releases/2013/01/130124183444.htm. -- Jo3sampl (talk) 19:33, 25 January 2013 (UTC)
replies: text: Seems anthropomorphic to me. Kortoso (talk) 21:43, 21 October 2014 (UTC)
thread_title:  New research 

message: The section on significant pulsars section has been tagged as "trivia" for awhile. It was just removed today (though I restored it) with the comment "no criterion for 'significance'". I think there are pretty clearly two criteria that encompass the majority of listed pulsars: "firsts" and record holders of various types. There are probably a couple of pulsars that don't really belong (and perhaps I'll just go ahead and trim the list a little after this), but for the most part it seems to be a fairly selectively populated list, and thus isn't truly a trivia section. I think the content and layout of the section could be improved, but disagree completely with removing it entirely. James McBride (talk) 04:54, 17 April 2013 (UTC)
thread_title:  Significant pulsars 

message: To root this article in something practical, how about talking about how the earth's position compared to 14 pulsars was the method used on the Pioneer plaques to describe our location to "aliens"?  I think a pic of the plaque would be a good graphic here as well.   It would show a newby one reason they are so important. Pb8bije6a7b6a3w (talk) 15:54, 14 May 2013 (UTC)
replies: text: Isn't this already in Pulsar#Applications? Reatlas (talk) 14:46, 15 May 2013 (UTC)
replies: text:  Statistically how many of the "aliens" would see any of these 14 pulsars as pulsating? 194.174.76.21 (talk) 18:35, 28 February 2017 (UTC)
thread_title:  pioneer plaque 

message: The sentence "It was not until a second pulsating source was discovered in a different part of the sky that the 'LGM hypothesis' was entirely abandoned" makes it sound like the little green men theory was disproven because there was more than one pulsar discovered. I'm pretty sure there's more science to it than that, but the cite given is not available to ordinary earthlings. Can someone summarize the science that tells us that pulsars are natural phenomena? Kortoso (talk) 17:22, 11 December 2013 (UTC)
replies: text: The entire article explains that.50.111.50.200 (talk) 13:07, 24 June 2020 (UTC)
thread_title:  Discovery 

message: Hello! In looking up pulsars, I saw the GIF Crab_Lucky_video2.gif (used in both the Pulsar and Crab Pulsar articles) caption simply saying that the GIF's animation speed was slowed down to illustrate the Crab Pulsar's pulses. The articles state that the Crab Pulsar's rotation period is 33 milliseconds, which is 1980 rotations per minute. What I can't seem to find, either on Wikipedia or via Googling other sources, is roughly how much the GIF is slowed down. The GIF appears to be about 1.5 seconds long to me, using Firefox. I think it would be both interesting and informative to have the caption state how much it was slowed down. I don't think '33 milliseconds' would be easy to grasp for the average person, while (for example, if my guess and math are right) 'slowed down by 45 times/4500%' would be more illustrative. Thanks! - Lafin T. Jack 23:34, 27 March 2014 (UTC)
thread_title:  Crab Pulsar GIF/video slow-down rate 

message: What shape and duty cycle are the pulses, and what frequency spectra (of the various type of pulsar). How does pulse width compare to the dispersion ? How do they compare to fast radio bursts ? - Where to look ? - Rod57 (talk) 12:18, 4 April 2015 (UTC)
replies: text: Shapes of 16 mS pulsars in 47 Tuc shown p1360 in Further results from the timing of the millisecond pulsars in 47 Tucanae. Freire et al. 2003. - Rod57 (talk) 08:59, 7 April 2015 (UTC)
thread_title:  Where are pulse shapes and spectra 

message: For all pulsars known in 2013 : See fig S2 on p8 of Supplementary materials for 'A Population of Fast Radio Bursts at Cosmological Distances', inc from Magellanic clouds. - Rod57 (talk) 01:21, 7 April 2015 (UTC)
thread_title:  Good plot of dispersion measure vs galactic latitude 

message: Since there is a table of pulsar ages, can we say how they are calculated - What does it depend on apart from period ? - Rod57 (talk) 01:29, 7 April 2015 (UTC)
thread_title:  How are pulsar ages calculated 

message: On the origin of a highly dispersed coherent radio burst (doi: 10.1111/j.1745-3933.2012.01306.x) says at least 14 of the pulsars (known in 2012) are known to exhibit giant pulses (inc the crab nebula pulsar). - Rod57 (talk) 01:46, 7 April 2015 (UTC)
thread_title:  No mention of giant pulses 

message: I have a vague memory of pulsars being considered as an indication of superluminal velocities in 1967, just after the little green men hypothesis was detroyed. It went something like this:
In 1967, the only objects thought to exist with the same energy as pulsars were quasars and, for a time, they were thought of as a type of quasars. Pulsars, as well as quasars, had a redshift which meant (in 1967) they were several million light-years away. However, they pulsed with a frequency of something like a second. Therefore, the generation mechanism couldn't be greater than one light-second across. Thus pulsars (A) must have enough energy to be detectible from millions of light-years (way less than one yocto-arc) and (B) must fit into a space not larger than the distance from Earth to the Moon. So we must examine new sources of energy and the possibility of FTL communication.
Of course, pulsars turned out to be neutron stars (mostly in our galaxy) and the red shift was due to their deep gravitational wells. But if someone could find sources, it would be a nice addendum to the Discovery section. Even if you can't, we should say something about pulsar's redshift. --RoyGoldsmith (talk) 11:12, 23 December 2017 (UTC)
thread_title:  Red shifts and faster than light 

message: That's not what the cited NYT article says and that sentence doesn't even make any sense. Atomic clocks are accurate to the nanosecond. How can pulsars be used as clocks that are accurate to the nanosecond!?  — Preceding unsigned comment added by Emilgul (talk • contribs) 21:29, 19 September 2018 (UTC)
replies: text: Yes some do. The best known is J0437-4715 which has a period of 0.005757451936712637 with an error of . Jim77742 (talk) 00:17, 9 January 2019 (UTC)
thread_title:  Pulsars definitely do not rival atomic clocks in their accuracy in keeping time 

message: Since recent discovery the longest period neutron star pulsar isnt PSR J2144-3933 anymore but PSR J0250+5854 with a period of 23.5 s.
Source:
http://iopscience.iop.org/article/10.3847/1538-4357/aade88/meta
https://phys.org/news/2018-10-student-slowest-pulsar-star.html —SuperErten (talk) 21:29, 23 October 2018 (UTC)
thread_title:  Significant pulsars update 

message: Attracting much press attention. Jim.henderson (talk) 02:21, 26 March 2019 (UTC)
thread_title:  PSR J0002+6216 

message: Currently, spider stars are not described in Wikipedia. However, this seems just a proposed name as I found it in the following preprint: 
* Deneva et al.: Timing of Eight Binary Millisecond Pulsars Found with Arecibo in Fermi-LAT Unidentified Sources (2021-01-01)
:* Rafi Letzter: Now-dead radio telescope finds bizarre venomous-spider star. On: LiveScience. 2021-01-18
The article uses also further designations: black widow (special kind of spider star), redback systems, ...
Maybe worth to mention in the article? --Ernsts (talk) 18:50, 19 January 2021 (UTC)
thread_title:  spider stars 

message: "PSR J0901-4046" Discovery of a radio-emitting neutron star with an ultra-long spin period of 76s with unusual spin properties. Notable ? - Rod57 (talk) 13:31, 31 May 2022 (UTC)
thread_title:  A new ultra-long period pulsar with low duty cycle