6 research outputs found
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 (ICARâRS) 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 ICARâRSâ2021 as well as updates to the original 140 topics. This executive summary consolidates the evidenceâbased findings of the document. Methods: ICARâRS presents over 180 topics in the forms of evidenceâbased reviews with recommendations (EBRRs), evidenceâbased reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICARâRSâ2021 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 evidenceâbased management algorithm is provided. Conclusion: This ICARâRSâ2021 executive summary provides a compilation of the evidenceâbased recommendations for medical and surgical treatment of the most common forms of RS