Something’s Always Been Off About the Crab Nebula. Webb Has Revealed Why!

Crab Nebula by JWST. Credit: NASA, ESA, CSA, STScI, T. Temim (Princeton University)

The Crab Nebula has always fascinated me, albeit amazed me that it doesn’t look anything like a crab! It’s the result of a star that exploded at the end of its life back in 1054 CE, leaving behind what is known as a supernova remnant. Back then the explosion would have been visible to the naked eye, even in daytime. It was thought that the supernova that led to the cloud was from a less evolved star with a core made from oxygen, neon and magnesium. Recent studies by the James Webb Space Telescope reveals that it may actually be the core collapse of an iron rich star. 

Continue reading “Something’s Always Been Off About the Crab Nebula. Webb Has Revealed Why!”

The Crab Nebula Looks Completely Different in X-Rays, Revealing its Magnetic Fields

Credits: Magnetic field lines: NASA/Bucciantini et al; X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech

Located about 6,500 light-years away in the constellation Taurus resides one of the best-studied cosmological objects known as the Crab Nebula (aka. Messier 1). Originally discovered in the 18th century by English astronomer John Bevis in 1731, the Crab Nebula became the first object included by astronomer Charles Messier in his catalog of Deep Sky Objects. Because of its extreme nature, scientists have been studying the Crab Nebula for decades to learn more about its magnetic field, its high-energy emissions (x-rays), and how these accelerate particles to close to the speed of light.

Astronomers have been particularly interested in studying the polarization of the x-rays produced by the pulsar and what that can tell us about the nebula’s magnetic field. When studies were first conducted in the 1970s, astronomers had to rely on a sounding rocket to get above Earth’s atmosphere and measure the polarization using special sensors. Recently, an international team of astronomers used data obtained by NASA’s Imaging X-ray Polarimetry Explorer (IXPE) to create a detailed map of the Crab Nebula’s magnetic field that has resolved many long-standing mysteries about the object.

Continue reading “The Crab Nebula Looks Completely Different in X-Rays, Revealing its Magnetic Fields”

Spin! Crab Pulsar Speed Jumps Linked To Billions Of Tiny Vortices

Artist's conception of a gamma-ray pulsar. Gamma rays are shown in purple, and radio radiation in green. Credit: NASA/Fermi/Cruz de Wilde

Pulsars — those supernova leftovers that are incredibly dense and spin very fast — may change their speed due to activity of billions of vortices in the fluid beneath their surface, a new study says.

The work is based on a combination of research and modelling and looks at the Crab Nebula pulsar, which has periodic slowdowns in its rotation of at least 0.055 nanoseconds. Occasionally, the Crab and other pulsars see their spins speed up in an event called a “glitch”. Luckily for astronomers, there is a wealth of data on Crab because the Jodrell Bank Observatory in the United Kingdom looked at it almost daily for the last 29 years.

A glitch, the astronomers said in a statement, is “caused by the unpinning and displacement of vortices that connect the [pulsar’s] crust with the mixture of particles containing superfluid neutrons beneath the crust.”

“Surprisingly, no one tried to determine a lower limit to glitch size before. Many assumed that the smallest glitch would be caused by a single vortex unpinning. The smallest glitch is clearly much larger than we expected,” stated Danai Antonopoulou from the University of Amsterdam.

The astronomers added they will need more observations of other pulsars to better understand the results.

You can read the paper at the Monthly Notices of the Royal Astronomical Society or in preprint version on Arxiv. The research was led by C.M. Espinoza of the University of Manchester and Chile’s Pontifical Catholic University.

Source: NOVA