HEAPOW: A Pulsar's Tail (2011 Jul 18)

[bystander]

HEAPOW: A Pulsar's Tail (2011 Jul 18)

Pulsars are rapidly spinning neutron stars. Beams of radiation emitted near the magnetic poles of the neutron star sweep through space as the star rotates, and in fortuitous circumstances that beam may pass over earth, so that observations (in radio wavelengths, in optical, and/or in high energy X-ray or Gamma rays) will detect a steady pulsation of radiation. Pulsars are born in extremely violent supernova explosions, though no one quite knows how. Somehow some of the violence of this explosion gets transferred into the rapid spin of the neutron star. Sometimes this explosion may propel the neutron star through space. The image above is an X-ray picture from the Chandra X-ray Observatory of a pulsar known as PSR J0357+3205, an object discovered by the Fermi Gamma-ray Space Telescope from the regular variations in its Gamma ray emission. Chandra's excellent spatial resolution and high contrast imaging reveals a surprise, a long tail of X-ray emission trailing behind the pulsar, as shown above. Astronomers are debating the meaning of this tail: whether it's an X-ray "wake" produced by the motion of the neutron star through the Milky Way. Or is it a jet of material associated with the pulsar's magnetic field? Future imaged of the pulsar to determine how rapidly it's moving through space will resolve this controversy, and add another piece to the puzzle of the supernova death of massive stars.

CXC: PSR J0357+3205: A Pulsar and its Mysterious Tail

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Author: Dr. Michael F. Corcoran

[ExplorerAtHeart]

How long and wide is the tail. Would it be possible for any star systems to get caught up in the tail something like this and have ill effects? Of course its possible but what is the likelyhood? I would imagine planets with magnetic fields having strong auroras as a result.

[Ann]

Space is mostly empty, so the chances of a runaway pulsar blundering into a solar system in the disk of a galaxy away from the most crowded central parts of it are exceedingly slim. There is definitely a greater risk that a runaway pulsar might get uncomfortably close to something inside a globular cluster:

Click to view full size image

47 Tucanae is the second brightest globular cluster of the Milky Way, after Omega Centauri. 47 Tucanae is also unusually compressed and dense. It also contains several pulsars. But there is little chance that a pulsar in 47 Tucanae will wreak havoc on an inhabited planet inside 47 Tucanae, because it would seem that globular clusters are hostile places for planets in general, and almost certainly very hostile places for planets with life forms. There are just too many rather violent things things going on inside a globular cluster - certainly when it comes to gravity and slingshot effects and the like! - for life to thrive in there.

I can't resist showing you this picture of bloated red giant star Mira, which also speeds through space leaving a wake behind it:



Unlike the pulsar, Mira doesn't have an X-ray tail, but an ultraviolet tail. Ultraviolet light represents a lower energy than X-rays, so the tails are not the same. Still, there are some similarities. Mira, too, is speeding, or at least moving pretty fast, through space.

Ann

[neufer]

HEAPOW: A Pulsar's Tail (2011 Jul 18)

Pulsars are rapidly spinning neutron stars. Beams of radiation emitted near the magnetic poles of the neutron star sweep through space as the star rotates, and in fortuitous circumstances that beam may pass over earth, so that observations (in radio wavelengths, in optical, and/or in high energy X-ray or Gamma rays) will detect a steady pulsation of radiation. Pulsars are born in extremely violent supernova explosions, though no one quite knows how. Somehow some of the violence of this explosion gets transferred into the rapid spin of the neutron star. Sometimes this explosion may propel the neutron star through space. The image above is an X-ray picture from the Chandra X-ray Observatory of a pulsar known as PSR J0357+3205,

How long and wide is the tail. Would it be possible for any star systems to get caught up in the tail something like this and have ill effects? Of course its possible but what is the likelyhood? I would imagine planets with magnetic fields having strong auroras as a result.

One must remind onesself that the Chandra X-ray Observatory ONLY observes "soft" X-rays.
Bomber safety glasses are not required.

<<X-rays from about 0.12 to 12 keV (10 to 0.10 nm wavelength) are classified as "soft" X-rays, and from about 12 to 120 keV (0.10 to 0.01 nm wavelength) as "hard" X-rays, due to their penetrating abilities. Hard X-rays can penetrate solid objects, and their most common use is to take images of the inside of objects in diagnostic radiography and crystallography. As a result, the term X-ray is metonymically used to refer to a radiographic image produced using this method, in addition to the method itself. By contrast, soft X-rays hardly penetrate matter at all; the attenuation length of 600 eV (~2 nm) X-rays in water is less than 1 micrometer.>>

[bystander]

PSR J0357+3205: A Pulsar and its Mysterious Tail
Chandra X-ray Observatory | 2011 July 13

Click to view full size image 1 or image 2

Credit: X-ray: NASA/CXC/IUSS/A.De Luca et al; Optical: DSS

A spinning neutron star is tied to a mysterious tail - or so it seems. Astronomers using NASA's Chandra X-ray Observatory have found that this pulsar, known as PSR J0357+3205 (or PSR J0357 for short), apparently has a long, X-ray bright tail streaming away from it.

This composite image shows Chandra data in blue and Digitized Sky Survey data in yellow. The position of the pulsar at the upper right end of the tail is seen by mousing over the image. The two bright sources lying near the lower left end of the tail are both thought to be unrelated background objects located outside our galaxy.

PSR J0357 was originally discovered by the Fermi Gamma Ray Space Telescope in 2009. Astronomers calculate that the pulsar lies about 1,600 light years from Earth and is about half a million years old, which makes it roughly middle-aged for this type of object.

If the tail is at the same distance as the pulsar then it stretches for 4.2 light years in length. This would make it one of the the longest X-ray tails ever associated with a so-called "rotation- powered" pulsar, a class of pulsar that get its power from the energy lost as the rotation of the pulsar slows down. (Other types of pulsars include those driven by strong magnetic fields and still others that are powered by material falling onto the neutron star.)

The Chandra data indicate that the X-ray tail may be produced by emission from energetic particles in a pulsar wind, with the particles produced by the pulsar spiraling around magnetic field lines. Other X- ray tails around pulsars have been interpreted as bow-shocks generated by the supersonic motion of pulsars through space, with the wind trailing behind as its particles are swept back by the pulsar's interaction with the interstellar gas it encounters.

However, this bow-shock interpretation may or may not be correct for PSR J0357, with several issues that need to be explained. For example, the Fermi data show that PSR J0357 is losing a very small amount of energy as its spin slows down with time. This energy loss is important, because it is converted into radiation and powering a particle wind from the pulsar. This places limits on the amount of energy that particles in the wind can attain, and so might not account for the quantity of X-rays seen by Chandra in the tail.

Another challenge to this explanation is that other pulsars with bow- shocks show bright X-ray emission surrounding the pulsar, and this is not seen for PSR J0357. Also, the brightest portion of the tail is well away from the pulsar and this differs from what has been seen for other pulsars with bow-shocks.

Further observations with Chandra could help test this bow-shock interpretation. If the pulsar is seen moving in the opposite direction from that of the tail, this would support the bow-shock idea.

Discovery of a faint X-ray counterpart and of a parsec-long X-ray tail for the middle-aged, gamma-ray only pulsar PSR J0357+3205 - A De Luca et al

• Astrophysical Journal 733(2) 104 (2011 June 01) DOI: 10.1088/0004-637X/733/2/104
  arXiv.org > astro-ph > arXiv:1102.3278 > 16 Feb 2011

Catch A Pulsar By The Tail
Universe Today | Tammy Plotner | 2011 July 15

How long and wide is the tail

If the tail is at the same distance as the pulsar then it stretches for 4.2 light years in length.

• Which makes it about 0.5 ly wide.