[New Tang Dynasty News, àm Beijing, 3 Iuchar, 2024]American astronauts useNASAThe James Webb Area Telescope (JWST) will analyze the composition of the Crab Nebula found by historical individuals about 1,000 years in the past.
In 1054 AD, Chinese language astronomers noticed a supernova (star) explosion within the Crab Nebula close to the constellation Taurus, 6,500 light-years away from Earth. The explosion was shiny sufficient to see in the course of the day.
The Crab Nebula was the primary object recognized because of a supernova explosion and is legendary for its crab-like look. Since its discovery, it has been one of the crucial studied substances. Immediately, the Crab Nebula that individuals can see not shines, however is the remnant of a faint supernova.
Astronomers have found that when a supernova explodes, most and even nearly all of its materials may be ejected at very excessive speeds to kind a nebula. The Crab Nebula is made up of gasoline, mud and excessive outflow winds (flowing within the interstellar medium). Kinds the intense pulsar wind nebula (PWN).
A neutron star is a neutron ball with a diameter of about 10 kilometers and a really excessive density. It’s regarded as produced by the core of a star collapsing below the affect of gravity throughout a supernova explosion, and has a mass equal to the dimensions of a standard star (normally about 1.5 occasions the mass of the Solar). The neutron stars that repeatedly emit pulses of radiation are referred to as “pulsars”.
Previously, astronomers calculated the full kinetic power of the Crab Nebula explosion based mostly on the quantity and pace of the ejecta. Nevertheless, the full power of the explosion was comparatively low (lower than a tenth of a standard supernova). Thus, up to now, the Crab Nebula’s progenitor stars have been believed to have been brought on by “electron seize kind” (ECSN) supernova explosions, somewhat than typical “iron core” supernova explosions.
A supernova explosion is mostly believed to be an “electron seize kind” supernova explosion during which the core of the supernova is especially composed of oxygen, neon and magnesium, somewhat than a typical iron core. After these oxygen, neon and magnesium atoms develop into too dense within the core, they start to soak up the electrons round them, inflicting the core stress to drop to quick, ultimately inflicting the core to break down quickly and leading to a stellar explosion.
Nevertheless, there are some inconsistencies between predictions of electron seize supernovae and previous observations of the Crab Nebula. As a result of theoretically, it’s anticipated that the abundance of nickel iron (Ni/Fe) within the core of a supernova ought to be a lot greater than the extent within the core of the Solar.
This time, to scale back the uncertainty in observing the celebrities of the Crab Nebula, the Princeton College astronomy analysis workforce in the USA used the Mid-Infrared Instrument (MIRI) and the Close to-Infrared Digicam (NIRCam ) within the JWST area telescope to be extra exact
The outcomes of the analysis have been printed within the Astrophysical Journal Letters on June 20.
They began by imaging a smaller pattern of argon, neon and oxygen at MIRI nuclear magnetic resonance (MRS). The instrument makes use of 4 completely different filters and a mix of various picture filters to make the picture of the Crab Nebula extra three-dimensional and clearer in the course of the synthesis course of, and in addition makes the picture be in numerous colours, in order that astronomers can higher determine its look. .
As well as, the workforce used MIRI’s spectroscopic evaluation capabilities to pattern the emission traces of iron (Fe), sulfur (S), mud and PWN to supply a extra dependable estimate of the co- estimate the abundance of iron-nickel.
A composite MIRI and NIRCam picture of the Crab Nebula exhibits that red-orange represents sulfur, blue exhibits iron, and yellow-white and inexperienced present mud emissions. NIRCam seen that the smoky white coloration comes from the Pulsar Wind Nebula (PWN).
As well as, the workforce used the JWST telescope to map the distribution of heat mud, which was mixed with knowledge from the Herschel Area Observatory on cooler mud particles to create a complete image of the distribution of high-resolution mud. The outermost filaments within the picture comprise comparatively heat mud, whereas cooler particles are usually nearer to the centre.
Additionally they used the JWST telescope to detect the iron-nickel ratio in two chosen areas of the Crab Nebula and monitor the distribution of those supplies all through area. The outcomes present that the ratio of iron-nickel richness is between 0.156 and 0.277, which is 2.8 to five.2 occasions greater than the iron-nickel richness ratio of the solar (0.053), nevertheless, the This knowledge is way decrease than the 50 to 75 occasions estimated by scientists up to now.
The info seen by the JWST telescope this time reveal unprecedented element in regards to the Crab Nebula and perceive the abundance of iron and nickel ejected from the PWN pulsar nebula. As well as, scientists in contrast the revised values with the electron seize supernova synthesis mannequin and located that the abundance of iron and nickel within the Crab Nebula is in line with the speculation “low iron core explosion” or “lightning seize supernova”. “explosion.
“Low mass iron core collapse” comes from astronomers’ new understanding of iron core collapse supernovae. Astronomers now imagine that lower-mass stars may produce low-energy iron core collapse explosions.
Tea Temim, an astronomer at Princeton College in the USA,NASAHe stated, “Now the info collected by the JWST telescope on the Crab Nebula has been expanded, which can clarify the formation of the crab. to blow up, in order that low-mass objects are used supernova collapse iron core to elucidate.”
“The place you see mud within the Crab Nebula is attention-grabbing as a result of it’s completely different from different supernova remnants, reminiscent of Cassiopeia,” stated astronomer Nathan Smith of the College of Arizona’s Steward Observatory. the objects A and 1987A are normally positioned within the heart, however the mud within the Crab Nebula is discovered within the dense fibers of the outer shell.”
Martin Laming, co-author of the paper and the US Naval Analysis Laboratory, stated, “At present, the Webb telescope spectroscopic knowledge covers two small areas of the Crab Nebula, so it is very important research extra particles and spatial variations “It might be attention-grabbing if we may determine different parts reminiscent of cobalt or germanium.”
Scientists stated they’ll proceed to research the info collected by the JWST telescope sooner or later and mix it with different observations to know the method of formation of the Crab Nebula and different celestial objects.
(Reprinted from The Epoch Instances/Editor: Ye Ping)
