Stars

The star WR 124 as seen by the James Webb Space Telescope (Image NASA, ESA, CSA, STScI, Webb ERO Production Team)

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An image captured by the James Webb Space Telescope shows the star WR 124 and the surrounding nebula in never-before-seen detail. This is a case where a star is nearing the end of its life, which could culminate in a supernova. For this reason, astronomers have been keeping an eye on WR 124 for years with various instruments and it was among Webb’s first observation targets in June 2022. The very powerful stellar wind typical of so-called Wolf-Rayet stars caused the loss of this star’s outer layers, which formed the nebula that surrounds it. Its details have now been captured in the breathtaking image thanks to Webb’s NIRCam and MIRI instruments to better understand the processes taking place before the possible supernova or another type of death.

A scheme of the passage from the universe full of neutral hydrogen and dark to the bright one following the epoch of reionization

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An article published in the journal “Astronomy & Astrophysics” reports the identification of a group of primordial galaxies that could be among the ones that contributed to the reionization of the universe, making it go from dark to bright. A team of researchers coordinated by the Italian National Institute of Astrophysics used observations conducted with the James Webb space telescope within the GLASS-JWST program to study 29 very distant and therefore ancient galaxies. The examination of those galaxies’ physical characteristics led the researchers to conclude that 80% of them contributed significantly to reionization.

The star X3a in its envelope of gas and dust (Image courtesy Florian Peißker)

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An article published in “The Astrophysical Journal” reports the discovery of a very young and massive star, cataloged as X3a, in an environment in which it shouldn’t exist, as it orbits Sagittarius A*, or simply Sgr A*, the supermassive black hole at the center of the Milky Way. A team of researchers led by Florian Peißker of the Institute of Astrophysics at the University of Cologne, Germany, used several instruments to locate X3a.

According to the researchers, the star must have formed in a cloud farther from Sagittarius A* and then been attracted by it. This suggests a model of star formation near an environment where conditions seem impossible.

Artist's concept of Scholz's star with its companion, a binary system that might be similar to LP 413-53AB (Image Michael Osadciw/University of Rochester)

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An article published in “The Astrophysical Journal Letters” reports the discovery that the system cataloged as LP 413-53AB consists of two ultracool dwarf stars that orbit each other in just 17 hours. A team of researchers led by Chih-Chun “Dino” Hsu of Northwestern University used observations conducted with the Keck Observatory telescopes to resolve two stars so small and so close. Previously, three binary systems composed of ultracool dwarfs had been discovered but they were young stars in astronomical terms while the pair of LP 413-53AB is estimated to be some billion years old. We don’t know how difficult these pairs are to find due to their weak emissions, and explaining the existence of LP 413-53AB is difficult.

Tycho supernova remnants (X-ray (IXPE: NASA/ASI/MSFC/INAF/R. Ferrazzoli, et al.), (Chandra: NASA/CXC/RIKEN & GSFC/T. Sato et al.) Optical: DSS Image processing: NASA/CXC/SAO/K. Arcand, L.Frattare & N.Wolk)

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An article to be published in “The Astrophysical Journal” reports a study on Tycho supernova remnants which offers new information on the geometry of its magnetic fields. A team of astronomers led by Riccardo Ferrazzoli of the Italian National Institute of Astrophysics used observations conducted with the IXPE space telescope to examine the polarized X-rays emitted by these supernova remnants. This allowed new clues to be found about the conditions in the shock waves generated by the supernova that accelerate particles to speeds close to the speed of light.