when your mum makes you try on clothes you don’t like
Pulsars are a very interesting breed of star. After a supernova explosion, the compact, super dense core that’s left behind is called a neutron star or pulsar that’s usually no bigger in diameter than a large city here on Earth. Beyond that, there are a couple different types of pulsars based on the rotational characteristics they display. Some pulsars rotate at a mild pace, anywhere from ten to a couple hundred times a minute. Another type of pulsar has the ability to rotate many thousands of times faster than that, which means one rotation can happen in milliseconds, thus giving them the name ‘millisecond pulsars’. The first millisecond pulsar was discovered in the late 1970s but wasn’t verified until the early 80s because at the time it wasn’t known that pulsars could spin at as fast as 1 millisecond. Now, after having discovered many other millisecond pulsars, astronomers using NASA’s Fermi Gamma-ray Space Telescope have seen something very interesting indeed.
About 4,400 light years away in the Sextans constellation is a binary pair known as AY Sextantis. A star about one fifth the mass of our sun is binary companion to a 1.7-millisecond pulsar named PSR J1023+0038, J1023 for short. Since the first discovery of a millisecond pulsar, astronomers had no clue as to how they got to spinning so fast until they started discovering more and more. It turned out that well over 50% of millisecond pulsars were, in fact, part of a binary system. Since pulsars do lose their momentum and energy over time, astronomers theorized that millisecond pulsars were ‘spun-up’ by their binary companions when they were close enough to each other. The idea is that the companion star would feed its pulsar to the point when the newly absorbed star material would start speeding it up. But since astronomers had never seen this in action, they couldn’t be certain, until April 2013.
A pulsar is called as such because, in reference to Earth, the intense radio and gamma-ray beams being expelled from the poles would sweep past Earth in such a fashion that a radio telescope would detect radio pulses. What makes J1023 special is that astronomers caught its radio beams disappearing and intense X-ray beams taking their place.
"It’s almost as if someone flipped a switch, morphing the system from a lower-energy state to a higher-energy one," said Benjamin Stappers, an astrophysicist at the University of Manchester, England and lead researcher to this project. "The change appears to reflect an erratic interaction between the pulsar and its companion, one that allows us an opportunity to explore a rare transitional phase in the life of this binary."
Like a black hole, a pulsar’s gravitational force can pull off so much star material from its companion that most of it will form into an accretion disk and steadily feed the pulsar. Every now and again, some of the material on the inside of the disk will lose orbital energy and start falling towards the surface of the pulsar, at which point the processes that create the radio beams become obscured and intense jets of X-rays take their place. Once the newly fallen material is either absorbed or burned up, the X-rays subside and the radio beams return to their normal state.
With this discovery, astronomers believe that they will be able to shed some light in the future on the subject of how millisecond pulsars form and if the ‘spin-up’ theory carries any weight.
IMAGE CREDIT: NASA’s Goddard Space Flight Center (Artist Rendition)
"These artist’s renderings show one model of pulsar J1023 before (top) and after (bottom) its radio beacon (green) vanished. Normally, the pulsar’s wind staves off the companion’s gas stream. When the stream surges, an accretion disk forms and gamma-ray particle jets (magenta) obscure the radio beam."
The ABC's of Avatar: The Last Airbender
This avatar side blog has been going strong for about 2 years now and somehow I reached 4,000+ followers a couple weeks ago! For me, this is a pretty big accomplishment so I wanted to do something different to celebrate. Instead of making icons, a follow forever, psd packs, etc, I decided to make this. A gif set that captures the essence of Avatar: The Last Airbender, a show we all fell in love with almost 10 years ago and still love to this day. Avatar was such a big part of my childhood and it feels like all I’ve done is blink and now I’m an adult starting college this fall! But ya know what? I’m ready to start my own grand adventure and who knows, maybe I’ll end up changing the world like my buddy Aang. (;
To all my lovely followers, this one’s for you! ♥