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Home / Science / After a Decade of Radio Silence, a Mysterious Star Is Showing Signs of Waking Up

After a Decade of Radio Silence, a Mysterious Star Is Showing Signs of Waking Up



After more than a decade of patience and expectation, astronomers have seen signs that one of the rarest stars known to science is waking up from its sleep.

It's called XTE J1810-197, and it's part of an exclusive club of strange stars – it's one of only four magnetic magnetars that have been found to emit radio waves.

At least he did, until a decade ago when those radio waves subsided. Now it is still moving and astronomers have their telescopes ready for recording.

It might not sound so exciting, but the magnetars themselves are incredibly strange. They are essentially "dead" stars which, for reasons we do not fully understand, have insanely powerful magnetic fields.

To put it in perspective these incredibly dense and collapsed stars can generate magnetic fields around 1

quadrillion times more powerful than Earth's. So, yes, they are strange.

We currently know of 23 magnetars, but XTE J1810-197 is another thing. While the magnets throw out all the high-energy material, XTE J1810-197 and only three other stars we have detected pulsed radio waves.

And then, at the end of 2008, his radio waves suddenly calmed down and remained this way [19659002] Until now.

From 8 December last year, researchers from the University of Manchester and Max-Planck-Institut fur Radioastronomie monitored a new flow of radio emissions from the most unusual cosmic object.

It is interesting to note that the profile of this new rhythm of radio waves shows some rather large differences since they were first noticed all those years ago.

"The variations in impulse seen so far from the source have been significantly less dramatic, in terms of time from hours to months, than in 2006", reports the research group

. Among them there are small ripples of activity on a millisecond scale that could be caused by small chills in the star's crust.

The fact is that we still don't know much about magnetars. They appear to form in the same way as your average neutron star, starting from the collapsing nucleus of a massive dying star that crushes the atoms so that their nuclei are pressed on one side to the other.

At some point the compact body begins to generate magnetic fields in the order of about 10 ^ 15 gauss. In comparison, a typical fridge magnet is about 50 gauss, which is still 100 times stronger than the magnetic field of our planet on the surface.

What causes such a powerful magnetism is a mystery, with many theories suggesting that everything could start with the star neutron that spins from hundreds to thousands of times per second and turns into a pulsar.

Think of a group of suns crammed into a space the size of a small town that is agitated with the ferocity of helicopter blades and you can begin to imagine these monsters.

If this is not intense enough, from their prediction at the end of the 80's, the magnetars have been associated with strange, irregular bursts of gamma rays and X-rays that are repeated in some parts of the sky .

The explanation for these massive explosions of powerful radiation are adjustments in the crust of the neutron-filled star – the magnetar equivalent of an earthquake – they remove its magnetic field in new alignments.

The strange thing about XTE J1810-197 is a year after it shone briefly in X – It goes back to 2003, astronomers noticed that it sighed in pulses of much more delicate radio waves. Initial observations noted that he spat out low-energy electromagnetic radiation once per lap, about every five and a half seconds.

It was the first of a handful of radio emission magnetars that have been discovered since then.

This exclusive class of stars blurs the lines between these magnetic monsters and the garden variety pulsars, their weakest magnetic fields that channel radiation rays that light up in radio waves that sweep the cosmos as they rotate.

Perhaps all magnetars produce radio waves in similar ways and we only see them in a few? Maybe there is something special about XTE J1810-197 and about the other three radio emitters?

Continuing in this new study, it is possible that tremors in the crowded neutron star crust not only realign its powerful magnetic field, but contribute directly to a range of electromagnetic frequencies that include radio waves.

The search is currently available on the pre-review site, arxiv.org, so it is set up to generate some discussion.

Another group of astronomers recently used the NASA Deep Space Network to monitor XTE J1810-197 and two of its radio magnetar cousins. They also noticed some strange variations in radio wave emissions.

Future observations may help to belittle speculation about what is behind these impulses and why they come and go as they do.

Now that one of the beasts is awake again, he may still have more to say about it.


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