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New Class of Pulsars Discovered
xyz writes "NASA's Fermi Gamma-ray Space Telescope has discovered a new class of pulsars which emit purely in gamma rays. A pulsar is a rapidly spinning neutron star, and of the nearly 1,800 cataloged so far, only a small fraction emit at frequencies higher than radio waves. The gamma-ray-only pulsar, which lies within a supernova remnant known as CTA 1, is silent across parts of the electromagnetic spectrum where pulsars are normally found, indicating a new class of pulsars. It is located 'about 4,600 light-years away in the constellation Cepheus. Its lighthouse-like beam sweeps Earth's way every 316.86 milliseconds. The pulsar, which formed in a supernova explosion about 10,000 years ago, emits 1,000 times the energy of our sun.'"
Odd thing is that the signal seems to be carrying a message. We have decoded it, and it seems to read: F-I-R-S-T---P-O-S-T-.
There was a recent Slashdot discussion on music from pulsars which didn't get quite the attention I wish it did. Along those lines, I'd again encourage all nerds here to check out Gerard Grisey's work Le Noire d'Etoile for six percussionists. This work is based in part on the periodicity of a certain pulsar, and at one moment the performers pause while the sound of another pulsar is acquired with a radio telescope and relayed over speakers in the hall. This would definitely appeal to the many nerds here with an astronomy bent, but it sadly remains little-known outside of IRCAM circles.
This proves they're from Chicagoland...
CTA....
3 busses will come within 316.86 milliseconds of each other,
then you'll wait 10,000 years for the next one.
It's not mentioned in the article, and I assume it's so obvious that it was ruled out before announcement, but is there anything to suggest that the pulsar is pulsing across all frequencies up to Gamma, and that intervening matter is simply blocking all but the high-energy Gamma portion of the pulse?
Yes it was mentioned:
This discovery by Fermi is different because it is a purely gamma-ray pulsar. The star is silent across parts of electromagnetic spectrum where pulsars are normally found and hints at a whole population of previously unsuspected pulsars waiting to be picked out of the heavens.
this nation, under God, shall have a new birth of freedom. -- Lincoln, Gettysburg Address
No natural object is spinning that fast.
You are obviously not aware about the United States forefathers in their graves, knowing what is going on in that nation.
It is dangerous to be right when the government is wrong.
Quantum mechanics you insensitive prick!
If only you hadn't looked at the report card. Then, your grade could've been an A or an F, and you wouldn't have known until you looked at the report card, thus collapsing the waveform.
And now you know why you only got a C.
My blog
Is there more to this than just a new object? Does it imply that certain models on how pulsars form need to be refined? Gamma rays are also incredibly high energy, what does it imply as for the structure of the pulsar that it doesn't emit lower frequencies?
What I'm getting at is pretty much that the article seem to just pass this off as a "ok, we have a new kind of pulsar here" without any follow up questions raised. IS there any questions to raise? Does this all fit neatly into what we know about pulsars, and is it easily explained why this one doesn't emit in lower frequencies, and only in a very high energy one?
I'm also surprised there are so much "junk" like the "yourmumisapulsar" tag and Obama posts, etc. Come on now, this is Slashdot, if I want the other stuff on science stories, I can read Digg. :-(
Beware: In C++, your friends can see your privates!
Isn't earth in danger of an extinction event when a gamma ray burst occurs from something about 6,000 light years away?
Although this thing does emit gamma rays, in discreet packets, this is not an example of the phenomenon knows as Gamma Ray Bursts (GRBs). The "burst" in a genuine GRB lasts much longer (seconds or minutes as opposed to milliseconds), happens only once, and contains orders of magnitude greater energy.
So when we say we're screwed if a GRB happens within 6,000 lt-yr of Earth (and it's pointed in our direction), that's absolutely true, but it doesn't apply to pulsars.
... we'll discover yet another class of pulsars, known as category WEB20, which emit purely Beta rays. And they reflect stuff!
Always proofread carefully to see if you any words out.
The radio emission is believed to come from a small patch near the surface of the neutron star called the polar cap. Hence, to see it, the pulsar has to be aligned just so with the line of sight to the Earth. Gamma ray emission appears to originate at a higher altitute, so there are more orientations of the pulsar with respect to the line of sight where we can see gamma rays. It's a geometrical effect.
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
Pulsars have extremely strong magnetic fields and rotate anywhere from 1-to-1000 times a second. Just like an electric generator, this produces huge electromagnetic fields, and these accelerate electrons to very high energies indeed. These electrons than bang into photons and give them a large chunk of energy in a process called inverse Compton scattering, and we get gamma rays.
(This is the so-called leptonic channel; it is also possible some gamma rays are produced via pions, but the origin of the energy is the same: the huge electromagnetic fields generated by this spinning magnetic dipole.)
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
I've found that gamma rays aren't the least bit discreet. They either make things disintegrate or turn people into man-spider hybrids.
Sorry, its high luminosity is more than offset by its distance of kiloparsecs. The relevant quantity is flux, which goes like luminosity/distance^2.
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
Wikipedia - Neutron Star
"On the basis of current models, the matter at the surface of a neutron star is composed of ordinary atomic nuclei as well as electrons."
It seems as one moves deeper into the star, the more it becomes a pure sea of neutrons. So all the charged matter on the surface, rotating around like crazy, creates the magnetic field which then causes the emission of radiation.