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Space Forum / SETI / February 2006Parkes telescope finds new kind of cosmic object
According to a release "Parkes telescope finds new kind of cosmic object" (16 Feb.,'06) http://www.atnf.csiro.au/news/press/rrats.html "A team of astronomers from the UK, USA, Australia, Italy and Canada using the CSIRO Parkes radio telescope in eastern Australia has found a new kind of cosmic object: small, compressed 'neutron stars' that show no activity most of the time but once in a while spit out a single burst of radio waves. The discovery is published in this week's issue of the journal Nature [16 February 2006]..." (Hey LT., I see that one of the contacts is Dr Jim Cordes. If you guys are still in contact, is there anything else that may be of interest to us SETIphiles?) Perusing the chaff of existence, Jason H. > According to a release "Parkes telescope finds new kind of cosmic > object" (16 Feb.,'06) [quoted text clipped - 13 lines] > > Perusing the chaff of existence, Jason H. Hmm, now that's intriguing Jason! What natural factors could cause such behavior? N-stars of odd composition? super-magnetic effects? ..cough..ETs?...cough.. Fascinating. ...tonyC >> According to a release "Parkes telescope finds new kind of >cosmic [quoted text clipped - 26 lines] >super-magnetic effects? ..cough..ETs?...cough.. Fascinating. >...tonyC Perhaps they've already eaten most of the material in their immediate environment, so they're not being fed continuously by an accretion disk. There's only a few small objects left in their system. When each object falls in, there's a single burst of energy.  SignatureMike Williams Gentleman of Leisure ...snip... > Perhaps they've already eaten most of the material in their immediate > environment, so they're not being fed continuously by an accretion disk. [quoted text clipped - 4 lines] > Mike Williams > Gentleman of Leisure Hi Mike (and Anthony), According to their release http://www.atnf.csiro.au/news/press/rrats.html "...Their isolated bursts last for between two and 30 milliseconds. In between, for times ranging from four minutes to three hours, they are silent." I wonder how much mass those bursts are equivalent to. Because the bursts are eventually repeating at intervals of <3 hours, it implies a semi-regular periodic influx of material. I imagine that planetary mass objects would be exhausted fairly quickly. Perhaps it's a warped accretion disk with a wobble caused by an massive interloper object that has affected the system, was either ejected from the system or is currently below the detection threshold? Perhaps its a high-period giant planet that shepherds debris from a disk into the neutron star. Perhaps E.T. is using a mass-driver to pulse the neutron star in periods that could only be interpreted as artificial? :^) I guess it all comes down to watching the burst intervals and energies. Does anyone here subscribe to Nature? Is there any room for an A-natural explanation? Regards, Jason H. >...snip... >> [quoted text clipped - 31 lines] > Does anyone here subscribe to Nature? Is there any room for an >A-natural explanation? Wouldn't a warped accretion disk or a high period planet tend to cause *regular* bursts, rather than the irregular bursts that are reported? Normal pulsars are able to pulse continuously for millennia. E.g. the pulsar at the heart of the Crab Nebula was created by a supernova in 1054, and is still extremely lively. If (and that's a big "if", nobody seems to really know) pulsars are fuelled by an infalling accretion disk, then the Crab Pulsar's disk has already provided fuel for something like 9*10^11 pulses. At that rate, a single pulse would correspond to quite a small infalling object. SignatureMike Williams Gentleman of Leisure The emission process for normal radio pulsars does not involve an accretion disk as it does for x-ray pulsars. The radio emission comes from highlly relativistic particles traveling along the magnetic field lines near the magnetic poles. These particles are generated near the surface of the star in a process that is driven by the rotation of the neutron star and the strength of the magnetic field. As pulsars age over many millions of years, their rotation slows down and the magnetic field may decay or align with the rotation axis. As this happens, the emission often becomes sporadic. These new intermittent radio sources may be an extreme example of what we've seen in older pulsars, or perhaps have an entirely different emission mechanism. It may be interesting to look for an x-ray burst coincident with the radio burst. That would suggest that an accretion disk is involved. I'll have to take a look at the paper to find out nore about the bursts. Peter Backus SETI Institute > >...snip... > >> [quoted text clipped - 42 lines] > something like 9*10^11 pulses. At that rate, a single pulse would > correspond to quite a small infalling object. >>>>> "JH" == Jason H <exosearch@juno.com> writes: JH> According to a release "Parkes telescope finds new kind of cosmic JH> object" (16 Feb.,'06) JH> http://www.atnf.csiro.au/news/press/rrats.html JH> "A team of astronomers from the UK, USA, Australia, Italy and JH> Canada using the CSIRO Parkes radio telescope in eastern Australia JH> has found a new kind of cosmic object: small, compressed 'neutron JH> stars' that show no activity most of the time but once in a while JH> spit out a single burst of radio waves. The discovery is published JH> in this week's issue of the journal Nature [16 February 2006]..." Hmm, I didn't realize that it had taken that long to get into print. (The paper was on astro-ph a while back.) Yes, these RRATs (umm, rotating radio transients, or something like that) are neat. They are not only showing that neutron stars have a considerably diversity of appearances, but they also illustrate that there is still a lot to learn about the radio sky. Peter Backus has already pointed out that they are unlikely to emit because something is falling onto their surfaces. I don't think anybody knows why they emit they way they do (but then "normal" pulsars still aren't all that well understood). One possibility is that these are extreme "nulling pulsars." There are pulsars whose emission seems to shut down for short periods, perhaps a few minutes. Maybe RRATs are an extreme variety? Another possibility is that these are neutron stars that do not normally pulse. However, occasionally something becomes unstable in their magnetosphere and the result triggers a single pulse? The Crab pulsar produces so-called "giant pulses," pulses that are so bright that they can outshine the entire Crab Nebula (admittedly for a very short period of time). There was a report a year or so ago about these giant pulses being found to be as narrow as 2 nanoseconds (meaning that the emitting region could probably fit easily within the room in which you are sitting right now). Perhaps these are a weak example of giant pulses? Nobody's sure; that's part of what makes it fun. SignatureLt. Lazio, HTML police | e-mail: jlazio@patriot.net No means no, stop rape. | http://patriot.net/%7Ejlazio/ sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html |
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