Stars

The galaxy Arp 220 as seen by the James Webb Space Telescope

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An image (NASA, ESA, CSA, STScI. Image processing: Alyssa Pagan (STScI)) captured by the James Webb Space Telescope portrays Arp 220, a galaxy that is the result, still not fully completed, of a galaxy merger. Intense processes are ongoing within this new galaxy as a consequence, starting with a remarkable star formation activity. X-ray emissions detected by other instruments suggest the presence of an active galactic nucleus. These are activities connected to its nature as an ultraluminous infrared galaxy (ULIRG) whose emissions allowed Webb to capture many new details.

The Cassiopeia A supernova remnant as seen by the James Webb Space Telescope

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An image of the supernova remnant cataloged as Cassiopeia A (NASA, ESA, CSA, D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (UGent), J. DePasquale (STScI)), or simply Cas A, captured by the James Webb Space Telescope shows never-before-seen details of the structures present within the materials surrounding what remains of the progenitor star. These are useful details for astronomers to reconstruct the processes that take place in the last stages of the life of a massive star and the consequences of a supernova. Elements generated by the star are scattered into space, including cosmic dust in quantities that could explain the abundance discovered in early galaxies.

Galaxy Z 229-15 (Image ESA/Hubble & NASA, A. Barth, R. Mushotzky)

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An image captured by the Hubble Space Telescope shows galaxy Z 229-15. A combination of the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) instruments with three different filters was used to obtain observations including ultraviolet, optical, and near-infrared emissions. Z 229-15 is a galaxy that defies simple classification criteria because it has a set of features not normally found together. The result is that it fits different definitions showing how sometimes classes and subclasses of galaxies don’t have precise boundaries but can overlap making different classifications valid.

The concentric rings generated by the GRB221009A gamma-ray burst as seen by the XMM-Newton space telescope (Image ESA/XMM-Newton/M. Rigoselli (INAF))

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A special issue of “The Astrophysical Journal Letters” is focused on the gamma-ray burst cataloged as GRB221009A, indicated since the first estimates of its characteristics as the gamma-ray burst of the century. Various teams of researchers conducted various types of analyzes of the data collected by many instruments that detected the emissions from GRB221009A and the so-called afterglow, meaning from the residues of its emissions, in several electromagnetic bands. The wealth of data indicates that this is the most powerful gamma-ray burst ever observed and offers new insights into these extremely energetic phenomena. In this case, it was a long gamma-ray burst, probably generated by the collapse of the core of a massive star and the subsequent birth of a black hole.

Photographs of the protostar IRAS20126+4104 and its material jets taken in 2012 and 2020 using the FLAO/PISCES and SOUL/LUCI1 instruments

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An article published in the journal “Astronomy & Astrophysics” reports a study on the massive protostar cataloged as IRAS20126+4104 which obtained the measurement of the speed of the jets of materials that are ejected at about 100 km/h. A team of researchers led by Fabrizio Massi of the Italian National Institute of Astrophysics in Arcetri used the SOUL instrument installed on the Large Binocular Telescope (LBT) to obtain the details necessary to measure the displacements that occurred with respect to archive images dating back to 2003 and 2012. This result helps to better understand the formation processes of massive stars.