A researcher at North Carolina State University has developed a three-dimensional computer model that shows how pulsars obtain their spin, which could lead to a greater understanding of the processes that occur when stars die.
Dr. John Blondin, professor of physics in NC State’s College of Physical and Mathematical Sciences, along with colleague Anthony Mezzacappa at the Oak Ridge National Laboratory, used the CRAY X1E supercomputer to develop a three-dimensional model of a pulsar’s creation, and in the process discovered that conventional wisdom concerning the formation of these celestial objects wasn’t correct.
Their findings are published in the Jan. 4 edition of the journal Nature.
Pulsars are rapidly rotating neutron stars formed in supernova explosions, which occur when a massive star reaches the end of its life and explodes. The remaining matter is compressed into a dense, rapidly spinning mass – a neutron star, or pulsar – so-called because scientists first discovered them due to their regularly timed radio emissions.
“Picture something about the mass of the sun being pushed down to the size of a small American city, like Raleigh,” Blondin says. “That’s what happens when a neutron star is formed.
“We’ve known about pulsars since the 1960s,” Blondin continues. “We can determine how fast they’re spinning by how rapidly they pulse. It’s like a searchlight on a lighthouse – each time the pulsar spins, and emits a radio pulse directed toward earth, we pick up on it. The period between the pulses tells us how fast it’s spinning.”
Pulsars spin very rapidly – 20 or more times per second. Scientists have assumed that the spin was caused by the conservation of angular momentum from a star that was spinning before it exploded.
“Think about figure skaters,” Blondin says. “They start a spin with their arms and legs farther out from the body, and increase their rotation speed when they pull their limbs in more tightly. That’s what the conservation of angular momentum is – the idea that if you take a large object with a slight rotation and compress it down, the rotation speed will increase.”
However, scientists had no idea if the stars that were producing the pulsars were even spinning to begin with. Blondin and his colleague decided to create a computer model of a supernova explosion using the new Cray X1E supercomputer at the National Center for Computational Sciences, the only computer with enough processing power to accomplish the task. The resultant model demonstrated that a pulsar’s spin doesn’t have anything to do with whether or not the star that created it was spinning; instead, the spin is created by the explosion itself.
“We modeled the shockwave, which starts deep inside the core of the star and then moves outward,” Blondin says. “We discovered that as the shockwave gains both the momentum and the energy needed to blow outward and create the explosion, it starts spiraling all on its own, which starts the neutron star at the center of the star spinning in the opposite direction. None of the previous two-dimensional modeling of supernova explosions had picked up on this phenomena.”
Blondin hopes that this new information about the creation of pulsars will lead to a greater understanding of supernova explosions. “Supernova explosions produce many of the heavy elements found on the periodic chart, like gold,” he says. “Understanding these explosions can help us to better understand our own planet and solar system.”
[ source ]
Image: PSR B1509-58. From NASA’s Chandra X-ray Observatory.
No sleep this month. Teething is everything people warned me it would be. Three in, two coming in, omfg… at least she’s getting it out of the way, right? I can’t see straight, I’m so tired.
I haven’t been posting much about politics lately, mostly because I’m too tired to do more than grunt to my husband about how angry I am over Obama’s secrecy bullshit and his unwillingness to hold anyone accountable for the United States’ torture policies during diaper changes. I’m furious enough to reconsider my own party membership. The lesser of two evils just isn’t lesser enough for me anymore.
These are rants I need to launch when I’m properly caffeinated, and have had more than 4 hours of sleep.
A ray of sunshine peeped into my political consciousness today when it was announced that Arlen Specter jumped ship. A little bit of funny I saw on the Huffington Post today:
Arlen Specter, the newly minted Democratic Senator from Pennsylvania, let his hair down in a freewheeling press conference at the U.S. Senate today, making this comment about his former Republican colleagues: “Now I can say it: what a bunch of fucking assholes!”
Mr. Specter had a bounce in his step and lilt in his voice as he tore into members of his former party in a press appearance that appeared to set records with its body count.
“This is something I’ve wanted to say for years: is there a bigger dick on this planet than Mitch McConnell?” he said. “I know he thinks he’s doing his job, but please, what a fucking turd.”
Observers who are accustomed to the much-ballyhooed collegiality of the Senate were taken aback by the jaw-dropping profanity of Sen. Specter’s parting shots, many of which were breathtaking in their anatomical crudeness.
“He must’ve had a lot of rage bottled up over the years,” said Sen. Dianne Feinstein (D-CA). “Suddenly he was talking like a Somali pirate.”
While Mr. Specter’s tirade had many high points – or low points, depending on one’s party affiliation – he reserved some of his harshest words for House Minority whip Eric Cantor: “Eric fucking Cantor? Please. That douche can kiss my goddamn stimulus package.”
I stole this from alicia-stardust…
I know I haven’t had time to post much lately, or read all the blogs of all the people on my f-list. Share a little something about yourself with this handy meme, and let’s get reacquainted!
1. name:
2. birthday:
3. place of residence:
4. what makes you happy:
5. what are you listening to now/have listened to last:
6. do you read my lj?:
7. if you do, what is particularly good/bad about it:
8. an interesting fact about you:
9. are you in love/do you have a crush at the moment:
10. favorite place to be:
11. favorite lyric:
12. best time of the year:
recommend:
1. a film:
2. a book:
3. a band, a song and an album:
plus:
1. one thing you like about me:
2. two things you like about yourself:
3. put this in your lj so i can tell you what i think of you
Please consider signing the ACLU’s petition calling on Attorney General Holder to appoint an independent prosecutor to investigate high-level involvement in torture.
From the Codex Anicia Juliana, AD 512
Have any of you guys been to DisneySea in Tokyo?
Will babble about the show at length when I have more brain…
Best show I have ever been to. And I’ve been to a lot of shows.
Accidentally kicked Richard Lewis in the ass a few times, which was awkward.
Sue and Del watched Lilith tonight, for which I’m eternally grateful.
Lilith woke us up at 6.30 this morning. I have a feeling tomorrow will be more of the same. Yay for caffeine.
Fourth row center pit for Leonard Cohen tonight! I am drooling with excitement…
I just stepped on a worm barefoot.
Good thing the little guy is resilient. >.>
