pulsar

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Millisecond Pulsars

As the name suggestions, millisecond pulsars have pulse periods that are in the range from one to ten milliseconds. Most such millisecond pulsars are found in binary systems, typically with white-dwarf companions. These pulsars are highly magnetized, old neutron stars in binary systems which have been spun up to high rotational frequencies by accumulating mass and angular momentum from a companion star. Neutron stars form when a massive star explodes at the end of its life and leaves behind a super-dense, spinning ball of neutrons. A pulsar is the same thing as a neutron star, but with one added feature. Pulsars emit lighthouse-like beams of x-ray and radio waves that rapidly sweep through space as the object spins on its axis. Most pulsars rotate just a few times per second, but some spin hundreds of times faster. These millisecond pulsars are the fastest-rotating stars we know of.

  • To hear the sound of a pulsar, click here

Credit: NASA

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Something strange is happening in our galaxy.

Gravitationally powerful stars called “pulsars”, essentially dead stars that are made of densely packed neutrons, are disappearing.

A single sugar cube’s worth of a pulsar weighs about 100 million tons (on Earth).

So what’s up? Well astronomers have predicted about how many should be around the center of our galaxy… and they’re way way off.

Currently estimates are predicting that they should be seeing about 50 young pulsars give or take. They’re only seeing one.

It’s a total mystery. No one knows why they’re disappearing but some have proposed that their intense gravity has been drawing in dark matter which build the mass up until they cross a threshold and implode into black holes.

The ‘Hand of God’ nebula.

Can you see the shape of a hand in this new X-ray image? 

The hand might look like an X-ray from the doctor’s office, but it is actually a cloud of material ejected from a star that exploded. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has imaged the structure in high-energy X-rays for the first time, shown in blue. Lower-energy X-ray light previously detected by NASA’s Chandra X-ray Observatory is shown in green and red.

Nicknamed the “Hand of God,” this object is called a pulsar wind nebula. It’s powered by the leftover, dense core of a star that blew up in a supernova explosion. The stellar corpse, called PSR B1509-58, or B1509 for short, is a pulsar: it rapidly spins around, seven times per second, firing out a particle wind into the material around it – material that was ejected in the star’s explosion. These particles are interacting with magnetic fields around the material, causing it to glow with X-rays. The result is a cloud that looks like an open hand. The pulsar itself can’t be seen in this picture, but is located near the bright white spot.

Image credit: NASA/JPL-Caltech/McGill

Pulsar encased in supernova bubble

Massive stars end their lives with a bang: exploding as spectacular supernovas, they release huge amounts of mass and energy into space. These explosions sweep up any surrounding material, creating bubble remnants that expand into interstellar space. At the heart of bubbles like these are small, dense neutron stars or black holes, the remains of what once shone brightly as a star.

Since supernova-carved bubbles shine for only a few tens of thousands of years before dissolving, it is rare to come across neutron stars or black holes that are still enclosed within their expanding shell. This image captures such an unusual scene, featuring both a strongly magnetised, rotating neutron star – known as a pulsar – and its cosmic cloak, the remains of the explosion that generated it.

This pulsar, named SXP 1062, lies in the outskirts of the Small Magellanic Cloud, one of the satellite galaxies of our Milky Way galaxy. It is an object known as an X-ray pulsar: it hungrily gobbles up material from a nearby companion star and burps off X-rays as it does so. In the future, this scene may become even more dramatic, as SXP 1062 has a massive companion star that has not yet exploded as a supernova.

Most pulsars whirl around incredibly quickly, spinning many times per second. However, by exploring the expanding bubble around this pulsar and estimating its age, astronomers have noticed something intriguing: SXP 1062 seems to be rotating far too slowly for its age. It is actually one of the slowest pulsars known.

While the cause of this weird sluggishness is still a mystery, one explanation may be that the pulsar has an unusually strong magnetic field, which would slow the rotation.

The diffuse blue glow at the centre of the bubble in this image represents X-ray emission from both the pulsar and the hot gas that fills the expanding bubble. The other fuzzy blue objects visible in the background are extragalactic X-ray sources.

Image credit: ESA/XMM-Newton/ L. Oskinova/M. Guerrero; CTIO/R. Gruendl/Y.H. Chu

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Messier Monday: The Teapot-Dome Cluster, M28

“A collection of eight stars stands out in this region of the sky, not because they’re the brightest stars around, but because they have a distinctive pattern to them that we recognize as very similar to a common object here on Earth. We call such a collection of stars an asterism, and the teapot is one of the most recognizable ones. And the star at the very top of the teapot’s lid — Kaus Borealis — has a secret less than a single degree away from it.”

What globular cluster is home to the first pulsar ever discovered in one? Learn about it on today’s Messier Monday!

One night in 1967, a pair of astronomers, Jocelyn Bell and Antony Hewish, detected a radio signal in an observatory in the UK.

It was one of the strangest things ever found. How could they explain it? Every 1.337302088331 seconds it pulsed with precision rivaling modern technology.

The astronomers were astounded. It didn’t seem like a natural phenomenon and we had no way to explain such a beacon’s origins.

In homage to the obvious answer the signal’s origin was dubbed LGM-1.

“Little Green Men”.

It was later found to be a whole new type of star: a pulsar. A stellar object that emits beacons with such regularity they’re used as clocks. The story is familiar though: our imagination fails to live up to the reality that is the cosmos.

Somehow the universe never ceases to surprise and amaze us.

*Also before I’m asked, yes: Joy Division did use an image of the radio signals - so there’s a little pop history for you too.

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A pulsar is a rapidly spinning neutron star which is the small, incredibly dense remnant of much more massive star. A teaspoon of matter from a neutron star weighs as much as Mount Everest. Check out this cool video from NASA Astrophysics.