#angular momentum

[Cueball sits sideways on a bed under an open window in the corner of a room. He is looking at Megan, who is spinning fast, indicated with two large circles indicating where her arms that are spread far out rotate, as well as two smaller circles around her knees and feet. The bed sheets are clearly messed up, as if someone has used it for activities other than sleeping. It is night and dark gray outside the window, and inside the room everything is also gray but lighter. Behind the spoken text, the background is white, but fades to the darker gray at the edges. There is also different gray shading in different parts of the room.] Cueball: What are you doing? Megan: Spinning counterclockwise Megan: Each turn robs the planet of angular momentum Megan: Slowing its spin the tiniest bit Megan: Lengthening the night, pushing back the dawn Megan: Giving me a little more time here Megan: With you

A team of scientists lead by Dr. Holger Pletsch(Max Planck Institute) collected data using NASA's Fermi satellite which is designed to find gamma radiation pulses. After a 4 year data collection period they were able to clearly identify a gamma pulse signal. Their calculations found that this is the fastest pulsar discovered so far, spinning at a staggering 390 times per second. This means a single rotation would take this pulsar roughly 2.5 milliseconds to complete. However, PSR J1311-3430 didn't get to this blistering speed on its own. What has now become a highly dense stellar core is the pulsar's companion star. The picture to the left is an artist’s rendition of the binary system. At eight times more massive than Jupiter yet a little over half the size, this stellar core has around 30 times the density of our sun. The companion stellar core, which was once a star, was slowly stripped of its material over time and absorbed by the pulsar. As a result PSR J1311-3430 accelerated to its current rotational speed. The companion being stripped of its stellar material also resulted in the two objects moving closer together and they are now orbiting their center of mass in about 93 minutes. The two objects are just under 1.5 times the distance of the moon from the Earth and the pulsar's orbit speed is around 13,000 km/h where the stellar core companion's orbit speed is just under 3 million km/h. "At present, the remaining stellar core, which presumably consists mainly of helium, is heated by the radiation from the pulsar and literally evaporated," said Holger Pletsch. What this means is that eventually the stellar core will be completely absorbed by the pulsar, hence the term black widow, and the pulsar will spend the rest of its life tumbling through space on its own. -TAZ Image Credit: SDO/AIA, AEI Source: https://science.sciencemag.org/content/338/6112/1314