The James-Webb continues to renew our knowledge of specific stars previously observed with Hubble and other orbiting telescopes such as Spitzer and Chandra. Today, the space telescope turns its gaze in the near-infrared to the remnants of the mythical supernova observed on Earth in 1987.
It is known that if we count supernovae in other galaxies over a year, all types combined (specifically SNSN II and SN Ia), we come to the estimate that on average three to four supernovae should occur on our planet per century. Milky WayMilky Way. However, the penultimate known one, for example before ChandraChandra’s recent observations, dates back to about 330 years ago. This is Cassiopeia A, and unlike those of 1572 and 1604 observed in visible light by Tycho Brahe (SN 1572) and Johannes KeplerJohannes Kepler (SN 1604), it appears to have gone unnoticed by astronomers. It was first discovered on the radio and in 1947.
However, astrophysicists believe that such a deficit is evident in supernovae. In fact, our Milky Way contains numerous dust clouds that strongly absorb visible light over interstellar distances. The fact remains that scientists are quite frustrated at their inability to closely examine, or even observe with the naked eye, an example of these cosmic catastrophes.
Since its discovery, telescopes around the world and in space have observed supernova 1987A. This includes NASA’s Chandra X-ray Observatory, which has studied this object several times over its 17 years of scientific operation. From 1999 to 2013, Chandra data showed an expanding X-ray emission ring that became increasingly bright. This was created by the shock wave from the original explosion that erupted and heated the gas ring around the supernova. To get a reasonably accurate French translation, click on the white rectangle at the bottom right. English subtitles should then appear. Then click on the nut to the right of the rectangle, then click on “Subtitles” and finally “Auto-translate”. Select “French”. © Chandra X-ray Observatory
A blue supergiant with 20 solar masses
Fortunately, almost the same thing happened when SN 1987A was discovered just 168,000 light-years from our galaxy in the Large Magellanic CloudLarge Magellanic Cloud. Since its discovery in February 1987, astrophysicists have continued to study the evolution of this gigantic explosion of a star that we saw in old images and which we named Sanduleak -69° 202a, abbreviated SK-69 202. It was a blue supergiant, formed from a star merger collision 10 million years ago and 20 times more massive than the Sun, which was originally mapped in 1970 by Romanian-American astronomer Nicholas Sanduleak.
Researchers have been using almost all wavelength bands from gamma radiation to radio for almost 40 years. Observations were made with HubbleHubble and Chandra. Therefore, we will not be surprised that today it is the turn of the James Webb Space Telescope, as explained in a press release from NASA.
The new observations were made with Webb’s NIRCamNIRCam (near-infrared camera) instrument. This gave us an image of a central structure of the remaining supernova in the form of a keyhole. It is so densely filled with gas and dust that even the near-infrared light discovered by Webb cannot penetrate, forming the dark “hole” in the keyhole.
A supernova remnant in continuous evolution
We are still observing a bright equatorial ring made of material ejected tens of thousands of years before the supernova explosion and containing bright hot spots that formed when the supernova’s shock wave overtook the supernova’s matter. ‘Ring.
The press release also explains that Webb’s unprecedented sensitivity and spatial resolution revealed small crescent-shaped structures. These crescents are believed to be part of the outer layers of gas ejected in the supernova explosion. Finally, he recalls that “despite decades of research since the first discovery of the supernova, some mysteries still remain, particularly regarding the neutron star that should have formed after the supernova explosion.”
Like Spitzer, Webb will continue to observe the supernova over time. Its NIRSpecNIRSpec (Near-Infrared Spectrograph) and MiriMiri (Mid-Infrared Instrument) instruments will give astronomers the ability to collect new high-resolution infrared data over time and gain new insights into newly identified crescent structures. “In addition, Webb will continue to work with Hubble, Chandra and other observatories to provide new information about the past and future of this legendary supernova.”
The explosion of very massive stars in gravitational supernovae enriches the interstellar medium with chemical elements synthesized by nuclear fusion and leads to the formation of a neutron star or a black hole through the collapse of the stellar core. The transition between core collapse and stellar envelope ejection poses a challenge to the theoretical understanding of supernovae. A hydraulic experiment designed and carried out at the CEA allowed the analogue reproduction of one of the phenomena of hydrodynamic instability that favored the explosion. This experimental approach complements numerical simulations. Discover this experience in animation. This animated film was produced and co-financed by CEA and ERC and directed by Studio Animéa. © T. Foglizzo, J. Guilet, G. Durand (CEA)
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