Zero Genie

In 1054 CE, Chinese sky watchers witnessed the sudden appearance of a ‘new star’ in the heavens, which they recorded as six times brighter than Venus, making it the brightest observed stellar event in recorded history. This ‘guest star,’ as they described it, was so bright that people saw it in the sky during the day for almost a month. Native Americans also recorded its mysterious appearance in petroglyphs. Observing the nebula with the largest telescope of the time, Lord Rosse in 1844 named the object the ‘Crab’ because of its tentacle-like structure. But it wasn’t until the 1900s that astronomers realized the nebula was the surviving relic of the 1054 supernova, the explosion of a massive star. Now, astronomers and visualization specialists from the NASA’s Universe of Learning program have used images from NASA’s Chandra X-ray Observatory, Hubble and Spitzer space telescopes to create a 3D representation of the Crab Nebula.

“Seeing 2D images of an object, especially of a complex structure like the Crab Nebula, doesn’t give you a good idea of its 3D nature,” said Dr. Frank Summers, a visualization scientist at the Space Telescope Science Institute.

“With this scientific interpretation, we want to help people understand the Crab Nebula’s nested and interconnected geometry. The interplay of the multiwavelength observations illuminate all of these structures. Without combining X-ray, infrared, and visible light, you don’t get the full picture.”

Certain structures and processes, driven by the pulsar engine at the heart of the nebula, are best seen at particular wavelengths.

The movie begins by showing the Crab Nebula in context, pinpointing its location in the constellation Taurus.

This view zooms in to present the Hubble, Spitzer, and Chandra images of the nebula, each highlighting one of the nested structures in the system.

The video then begins a slow buildup of the 3D X-ray structure, showing the pulsar and a ringed disk of energized material, and adding jets of particles firing off from opposite sides of the energetic dynamo.

Appearing next is a rotating infrared view of a cloud enveloping the pulsar system, and glowing from synchrotron radiation. This distinctive form of radiation occurs when streams of charged particles spiral around magnetic field lines. There is also infrared emission from dust and gas.

The visible-light outer shell of the Crab Nebula appears next.

Looking like a cage around the entire system, this shell of glowing gas consists of tentacle-shaped filaments of ionized oxygen. The tsunami of particles unleashed by the pulsar is pushing on this expanding debris cloud like an animal rattling its cage.

The X-ray, infrared, and visible-light models are combined at the end of the movie to reveal both a rotating 3D multiwavelength view and the corresponding 2D multiwavelength image of the Crab Nebula.

The 3D structures serve as scientifically informed approximations for imagining the nebula.

This composite image of the Crab Nebula was assembled by combining data from five telescopes spanning nearly the entire breadth of the electromagnetic spectrum: the VLA (radio) in red; Spitzer (infrared) in yellow; Hubble (visible) in green; XMM-Newton (ultraviolet) in blue; and Chandra (X-ray) in purple. Image credit: NASA / ESA / NRAO / AUI / NSF / G. Dubner, University of Buenos Aires.

“The 3D views of each nested structure give you an idea of its true dimensions,” Dr. Summers said.

“To enable viewers to develop a complete mental model, we wanted to show each structure separately, from the ringed disk and jets in stark relief, to the synchrotron radiation as a cloud around that, and then the visible light as a cage structure surrounding the entire system.”

These nested structures are particular to the Crab Nebula.

They reveal that the nebula is not a classic supernova remnant as once commonly thought. Instead, the system is better classified as a pulsar wind nebula.

A traditional supernova remnant consists of a blast wave, and debris from the supernova that has been heated to millions of degrees.

In a pulsar wind nebula, the system’s inner region consists of lower-temperature gas that is heated up to thousands of degrees by the high-energy synchrotron radiation.

“It is truly via the multiwavelength structure that you can more cleanly comprehend that it’s a pulsar wind nebula,” Dr. Summers said.

“This is an important learning objective. You can understand the energy from the pulsar at the core moving out to the synchrotron cloud, and then further out to the filaments of the cage.”

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This article is based on text provided by the National Aeronautics and Space Administration.