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EI2GYB > ASTRO 02.11.23 14:52l 104 Lines 5634 Bytes #999 (0) @ WW
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Subj: The Crab Nebula seen in new light by NASA's Webb
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The Crab Nebula seen in new light by NASA's Webb
Exquisite, never-before-seen details help unravel the supernova remnant's
puzzling history
Date:
October 30, 2023
Source:
NASA/Goddard Space Flight Center
Summary:
NASA's James Webb Space Telescope has gazed at the Crab Nebula, a supernova
remnant located 6,500 light-years away in the constellation Taurus. Since the
recording of this energetic event in 1054 CE by 11th-century astronomers, the
Crab Nebula has continued to draw attention and additional study as scientists
seek to understand the conditions, behavior, and after-effects of supernovae
through thorough study of the Crab, a relatively nearby example.
NASA's James Webb Space Telescope has gazed at the Crab Nebula, a supernova
remnant located 6,500 light-years away in the constellation Taurus. Since the
recording of this energetic event in 1054 CE by 11th-century astronomers, the
Crab Nebula has continued to draw attention and additional study as scientists
seek to understand the conditions, behavior, and after-effects of supernovae
through thorough study of the Crab, a relatively nearby example.
Using Webb's NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument),
a team led by Tea Temim at Princeton University is searching for answers about
the Crab Nebula's origins.
"Webb's sensitivity and spatial resolution allow us to accurately determine the
composition of the ejected material, particularly the content of iron and
nickel, which may reveal what type of explosion produced the Crab Nebula,"
explained Temim.
At first glance, the general shape of the supernova remnant is similar to the
optical wavelength image released in 2005 from NASA's Hubble Space Telescope:
In Webb's infrared observation, a crisp, cage-like structure of fluffy gaseous
filaments are shown in red-orange. However, in the central regions, emission
from dust grains (yellow-white and green) is mapped out by Webb for the first
time.
Additional aspects of the inner workings of the Crab Nebula become more
prominent and are seen in greater detail in the infrared light captured by
Webb. In particular, Webb highlights what is known as synchrotron radiation:
emission produced from charged particles, like electrons, moving around
magnetic field lines at relativistic speeds. The radiation appears here as
milky smoke-like material throughout the majority of the Crab Nebula's interior.
This feature is a product of the nebula's pulsar, a rapidly rotating neutron
star. The pulsar's strong magnetic field accelerates particles to extremely
high speeds and causes them to emit radiation as they wind around magnetic
field lines. Though emitted across the electromagnetic spectrum, the
synchrotron radiation is seen in unprecedented detail with Webb's NIRCam
instrument.
To locate the Crab Nebula's pulsar heart, trace the wisps that follow a
circular ripple-like pattern in the middle to the bright white dot in the
center. Farther out from the core, follow the thin white ribbons of the
radiation. The curvy wisps are closely grouped together, outlining the
structure of the pulsar's magnetic field, which sculpts and shapes the nebula.
At center left and right, the white material curves sharply inward from the
filamentary dust cage's edges and goes toward the neutron star's location, as
if the waist of the nebula is pinched. This abrupt slimming may be caused by
the confinement of the supernova wind's expansion by a belt of dense gas.
The wind produced by the pulsar heart continues to push the shell of gas and
dust outward at a rapid pace. Among the remnant's interior, yellow-white and
green mottled filaments form large-scale loop-like structures, which represent
areas where dust grains reside.
The search for answers about the Crab Nebula's past continues as astronomers
further analyze the Webb data and consult previous observations of the remnant
taken by other telescopes. Scientists will have newer Hubble data to review
within the next year or so from the telescope's reimaging of the supernova
remnant. This will mark Hubble's first look at emission lines from the Crab
Nebula in over 20 years, and will enable astronomers to more accurately compare
Webb and Hubble's findings.
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