The massive binary companion star to the progenitor of supernova 1993J

The massive star which underwent core-collapse to produce SN1993J was identified as a non-variable red supergiant star in images of the galaxy M81 taken before explosion. However the stellar source showed an excess in UV and B-band colours that suggested it had either a hot, massive companion star or was embedded in an unresolved young stellar association. The spectra of SN1993J underwent a remarkable transformation between a hydrogen-rich Type II supernova and a helium-rich (hydrogen-deficient) Type Ib. The spectral and photometric peculiarities were explained by models in which the 13-20 solar mass supergiant had lost almost its entire hydrogen envelope to a close binary companion. The binary scenario is currently the best fitting model for the production of such type IIb supernovae, however the hypothetical massive companion stars have so far eluded discovery. Here we report the results of new photometric and spectroscopic observations of SN1993J, 10 years after explosion. At the position of the fading SN we detect the unambiguous signature of a massive star, the binary companion to the progenitor. This is evidence that this type of SN originate in interacting binary systems.Comment: 18 pages (3 figures

A modern guide to quantitative spectroscopy of massive OB stars

Quantitative spectroscopy is a powerful technique from which we can extract information about the physical properties and surface chemical composition of stars. In this chapter, I guide the reader through the main ideas required to get initiated in the learning process to become an expert in the application of state-of-the-art quantitative spectroscopic techniques to the study of massive OB stars. NB: This chapter is intended to serve to young students as a first approach to a field which has attracted my attention during the last 20 years. I should note that, despite its importance, at present, the number of real experts in the field around the world is limited to less than 50 people, and about one third of them are close to retirement. Hence, I consider that this is a good moment to write a summary text on the subject to serve as guideline for the next generations of students interested in joining the massive star crew. If you are one of them, please, use this chapter as a first working notebook. Do not stop here. Dig also, for further details, into the literature I quote along the text. And, once there, dig even deeper to find all the original sources explaining in more detail the physical and technical concepts that are presently incorporated into our modern (almost) automatized tools.Comment: Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556

International Consensus Statement on Rhinology and Allergy: Rhinosinusitis

Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR‐RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR‐RS‐2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence‐based findings of the document. Methods: ICAR‐RS presents over 180 topics in the forms of evidence‐based reviews with recommendations (EBRRs), evidence‐based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICAR‐RS‐2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence‐based management algorithm is provided. Conclusion: This ICAR‐RS‐2021 executive summary provides a compilation of the evidence‐based recommendations for medical and surgical treatment of the most common forms of RS