Pulsars slow down their rotation as they age and eventually cease their characteristic emissions. That can change if an aging pulsar is a member of a binary system containing a normal star. Gas flowing from the star can spin the pulsar up to hundreds of revolutions a second and allow it to resume its lighthouse-like beams of radiation. Credit: NASA
Radio searches netted 17 new millisecond pulsars by examining the Fermi Gamma-ray Space Telescope’s list of unidentified sources. Colored circles indicate the positions of the new pulsars on the Fermi one-year all-sky map. Credit: NASA/DOE/Fermi LAT Collaboration
› Larger image Radio astronomers have uncovered 17 millisecond pulsars in our galaxy by studying unknown high-energy sources detected by NASA’s Fermi Gamma-ray Space Telescope. The astronomers made the discovery in less than three months. Such a jump in the pace of locating these hard-to-find objects holds the promise of using them as a kind of “galactic GPS” to detect gravitational waves passing near Earth.
A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Because only rotation powers their intense gamma-ray, radio and particle emissions, pulsars gradually slow as they age. But the oldest pulsars spin hundreds of times per second — faster than a kitchen blender. These millisecond pulsars have been spun up and rejuvenated by accreting matter from a companion star.
“Radio astronomers discovered the first millisecond pulsar 28 years ago,” said Paul Ray at the Naval Research Laboratory in Washington. “Locating them with all-sky radio surveys requires immense time and effort, and we’ve only found a total of about 60 in the disk of our galaxy since then. Fermi points us to specific targets. It’s like having a treasure map.”
Millisecond pulsars are nature’s most precise clocks, with long-term, sub-microsecond stability that rivals human-made atomic clocks. Precise monitoring of timing changes in an all-sky array of millisecond pulsars may allow the first direct detection of gravitational waves — a long-sought consequence of Einstein’s relativity theory.
“The Global Positioning System uses time-delay measurements among satellite clocks to determine where you are on Earth,” explained Scott Ransom of the National Radio Astronomy Observatory in Charlottesville, Va. “Similarly, by monitoring timing changes in a constellation of suitable millisecond pulsars spread all over the sky, we may be able to detect the cumulative background of passing gravitational waves.”
The sources Fermi detected are not associated with any known gamma-ray emitting objects and did not show evidence of pulsing behavior. However, scientists considered it likely that many of the unidentified sources would turn out to be pulsars.
For a more detailed look at radio wavelengths, Ray organized the Fermi Pulsar Search Consortium and recruited a handful of radio astronomers with expertise in using five of the world’s largest radio telescopes — the National Radio Astronomy Observatory, Robert C. Byrd Green Bank Telescope in W.Va., the Parkes Observatory in Australia, the Nancay Radio Telescope in France, the Effelsberg Radio Telescope in Germany and the Arecibo Telescope in Puerto Rico.
After studying approximately 100 targets, and with a computationally intensive data analysis still under way, the discoveries have started to pour in.
“Other surveys took a decade to find as many of these pulsars as we have,” said Ransom, who led one of the discovery groups. “Having Fermi tell us where to look is a huge advantage.”
Four of the new objects are “black widow” pulsars, so called because radiation from the recycled pulsar is destroying the companion star that helped spin it up.
“Some of these stars are whittled down to masses equivalent to tens of Jupiters,” said Ray. “We’ve doubled the known number of these systems in the galaxy’s disk, and that will help us better understand how they evolve.”
NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
Francis Reddy
Goddard Space Flight Center
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Gravity waves still not found?
DARPA and NASA have been looking at this concept (XNAV) for quite a few years now. Here’s a nice overview of a recent study…
http://www.asterlabs.com/publications/2007/Graven_et_al,_ION_63_AM_April_2007.pdf
Dave Salt (05:11:29) :
DARPA and NASA have been looking at this concept (XNAV) for quite a few years now.
Many thanks for that background paper, Dave. Just looking at the headline I was wondering how you would manage to receive millisecond pulsar signals on a hand portable 🙂 – the paper you reference gives details. Good stuff, but not easy, though possible on a spacecraft.
I wonder what the intention is with regard to detection of gravitational waves – presumably it would be to use a spacecraft as the reference object that the gravitaional waves perturb – and presumably also it would also be limited to the lower frequency gravitational waves, since pulsar frequencies tend to be in the millisecond range rather than the nanosecond range of GPS earth orbiting satellites.
Fascinating stuff – thanks Andrew.
For the sake of clarity: Radio signals are electric signals unless otherwise stated by the “de la belle epoque” science.
Voyager.
We have sent the location of our species into the void in the form of a pulsar map etched onto plaques fitted to our spacecraft.
What was the very first thing the old time mariners did when they saw a strange vessel approaching? They destroyed any map that could lead a potential enemy to their home port.
We learn nothing from history it seems.
Henry Galt (06:35:58) :
Voyager.
Too late. We’ve been transmitting our radio then TV signals into space for over 100 years – so they’re now reaching stars up to 100 light years away. If “they” 🙂 can’t detect and locate the origin of our radio and TV signals then their technology isn’t great! Radio waves travel considerably faster than Voyager.
Perhaps gravitational waves cannot be detected because they do not exist. Too bad these experiments aren’t a definitive test for existence/non-existence.
Fear not John Cooke, it seems that our myriad signals disolve into the background radio noise, but a few light-yearsout from Earth. (I’m Googling for a reference, I heard this on a radio programme some weeks back, but can’t find a reference)
John Cooke (06:55:52) : A good idea it would be to modulate the Sun at will… who knows if the all powerful “Al Baby” and Nobel prize winner, could make it..☺
The study of the phenomena that is called gravity has a challenges. I think it is a great area for fundamental science advancement.
I found the speed comparison to a kitchen blender oddly unfathomable and quite out of place -as I remember, the (ungeared) speed of a fractional-horsepower electric motor, as used in this sort of appliance, is 1500rpm. I have no idea of the rotational speed of the blade/stirrer on any blender as this sort of knowledge is seemingly unavailable. So how fast was the author inferring?
John Whitman (07:39:13) : The study of the phenomena that is called gravity has a challenges. I think it is a great area for fundamental science advancement.
Read The Field by Lynne McTaggart. How the Zero Point Field postulated by quantum mechanics enfolds gravity… and more… real cutting edge research by top scientists IMO, ostracised by the mainstream, wonder where we’ve heard that one before.
Even if aliens are clever enough to weed out the signal of our TV/Radio broadcasts from the noise of our sun, and even supposing they find Voyager… the reality is we’re just not that interesting. The truth comes from Doug Adams wherein we see that whole alien civilizations and clusters of civilizations have existed for millions of years, and earth was so uninteresting that it didn’t even blip on their radar until it had to be destroyed for a cosmic superhighway.
This is probably closest to the truth. Do the developed nations go and invade a remote swampland containing a primitive tribe just because they found a primitive smoke signal coming from them, or discovered a runic tablet explaining where they are? No. Sometimes wars spill over into such areas, but space is likely very different than land in how war is fought. The extreme likelihood is if aliens exist and life is plentiful in the universe, then the only aliens among us are researchers who are trying to finish their doctoral thesis and they’re stuck on earth until their advisor says they’re done.
So, the reality that I find most likely is that the eyes of aliens we’re just a very backwards planet with no significant resouces and noone in space will ever give a d*mn about us until we get our sh*t together and start exploring the cosmos.
@ur momisugly John Cooke (06:55:52):
Not necessarily true. Our radio and TV signals weaken and get perturbed over the trip out. Opinions vary widely on how far out advanced technology could detect our signals separate from background noise, but they seem to be between 2 to 50 light years out. Probably on the lower end for most of our signals. Not very far in the overall scheme of things.
This article appears to be explaining the conclusion reached as a result of some puzzling data. Their explanation as to what is going on seems increasingly improbable and bizarre.
Translating this article to what I think they are saying, in relation to the observations…
Pulsars emit rapid pulses of radio waves (aka electric signals), and have been observed slowing down. Now we have observed some that speed up! So we have to concoct some explanation for it and this is our best shot.
In a normal world, finding a pulsar that speeds up should bring the whole spinning-as-fast-as-a-blender-star idea into question and send everyone back to the drawing board. But since this is not the normal world the anomalous data has to be explained away by shoring up the existing theory, with another improbable explanation. Namely, that there exists an improbable mechanism that enables one star to effect another that is already spinning ridiculously fast, such that it will spin even more ridiculously faster.
Put this same observation into the electric oscillator model of pulsars, and an entirely different conclusion may be reached. Both the slowing down and the speeding up have an obvious explanation if the resistance in the circuit between two capacitative bodies is changing or there are local changes in the electrical environment surrounding and powering the two stars in the oscillator. Changes in the resistivity of the “transmission line” of current in the space between the two capitative bodies would easily explain this phenomenon, and many others.
So this article is a missed opportunity to apply some falsifying data to one theory and some strengthening data to another.
The article does provide yet another example of how science by plugging away at only promoting the consensus view doesn’t really work. Why are they so insecure, could they not simply say, we observed this, and it confused the heck out of us, does anyone have any better ideas? To which the answer would be yes.
http://adsabs.harvard.edu/full/1995Ap&SS.227..229H
Oh and if, as they suggest one of the bodies in the binary system, is loosing mass, and hence capacitative size then that too would speed up the oscillations.
Lucy Skywalker (08:28:14) :
” Read The Field by Lynne McTaggart. How the Zero Point Field postulated by quantum mechanics enfolds gravity… and more… real cutting edge research by top scientists IMO, ostracised by the mainstream, wonder where we’ve heard that one before. ”
Lucy,
I will read your reference. Thanks.
Gravity study has always been a open question in my mind, it has seemed fundamentally lacking. I am a BS nuclear engineering (got it when the Beatles were still together), worked for a US nuclear OEM for 30 years and now do nuclear power consulting internationally. Physics in general I have some comfort with, just question gravity concepts fundamentally.
John
Of course this means that “I Love Lucy” has reached Vega
@ur momisugly keith (08:37:56)
This article isn’t trying to explain pulsars scientifically at all. The text is an attempt at giving a broad laymans explanation of what pulsars do and why we think they do what they do to people trying to understand the technology of determining your 3D Vector in space.
However, to my understanding, their explanation:
“A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Because only rotation powers their intense gamma-ray, radio and particle emissions, pulsars gradually slow as they age. But the oldest pulsars spin hundreds of times per second — faster than a kitchen blender. These millisecond pulsars have been spun up and rejuvenated by accreting matter from a companion star.”
…isn’t the best.
snowmaneasy (08:50:46),
The aliens will have a tough time deciding if they should invade Earth or not, depending on whether they tune in to “I Love Lucy” or “Superman”. But they’d better think twice; in a few more years they’ll see all the hi-tech gear we’ve got on “Get Smart”…
Alexander (07:53:10), I seem to recall that the pulsar in the Crab Nebula spins at around 1800 rpm, close to b-flat.
Great work!
NASA/DOE/Fermi LAT Collaboration are to be congratulated.
SUGGESTION:
a.) Change, “A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes.”
b.) To, “A pulsar is a rapidly spinning neutron star.”
WHY? Many scientists and ordinary citizens believe that neutron stars are dead nuclear embers that remain after a star explodes.
Nothing could be further from the truth.
In a neutron star, every neutron is highly energized by repulsive interactions between neutrons [“Attraction and repulsion of nucleons: Sources of stellar energy”, Journal of Fusion Energy 19 (2001) 93-98; “Neutron repulsion confirmed as energy source”, Journal of Fusion Energy 20 (2002) 197-201].
A central neutron star may explain the energy, neutrinos, and Hydrogen pouring from the surface of any “ordinary” star:
http://www.omatumr.com/Photographs/Suns_core.htm
With kind regards,
Oliver K. Manuel
JonesII (06:26:02) :
For the sake of clarity: Radio signals are electric signals
No, they are not.
Oliver K. Manuel (09:14:28) :
WHY? Many scientists and ordinary citizens believe that neutron stars are dead nuclear embers that remain after a star explodes.
Nothing could be further from the truth.
What you said next:
A central neutron star may explain the energy, neutrinos, and Hydrogen pouring from the surface of any “ordinary” star
is what is furthest from the truth.
John Whitman (07:39:13) :Yes, because laws, no matter how accurate, are but artifacts which describe reality but they do not necessarily reveal real causes.
Real causes are needed not beliefs. Empiriscism comes from empireia=practice in greek, laws should be reproducible in the lab otherwise are pure and self indulging imagination.
empiricism emphasizes those aspects of scientific knowledge that are closely related to evidence, especially as discovered in experiments
http://en.wikipedia.org/wiki/Empiricism
A method of reasoning is that of negation and solution by the absurd. If we face a difficult problem to solve, instead of seeking for adjusting reality to a “convenient” mathematical entelechia we could propose the negation of the existence of the phenomenon itself, as a way of finding out its real causes. We then clear up our mind of pre conceptions and start our “pillow thinking”..