Published Topical Collection “Unexplained Spectral Phenomena in the ISM”

July 2021

We are pleased to present the Topical Collection “Unexplained Spectral Phenomena in the ISM”, with Guest Editor Prof. Sun Kwok. It is focused on the investigation of spectral phenomena, that even though are pervasively observed in a range of astrophysical environments, remained unidentified after decades of observations. The understanding of diffuse interstellar bands (DIBs) and other spectral features remain some of the key challenges to explain the signature of organic materials in the interstellar medium. 

Read the editorial by Guest Editor Prof. Sun Kwok here.

Access the complete topical collection through this link.

Following the release of the editorial on July 26th 2021, the complete Topical Collection is available for free access for two months starting on July 28th 2021


Hubble Space Telescope image of the planetary nebula NGC 7027 with its spectrum from ISO (Infrared Space Observatory, from the European Space Agency) superimposed, showing the Unidentified Infrared Bands (labeled in green; the purple labels are atomic lines).


Our Guest Editor Prof. Sun Kwok is Professor Emeritus at The University of Hong Kong, and Honorary Professor at the University of British Columbia. His research is focused mainly on interstellar chemistry and stellar evolution. He is widely recognized for his theory on the origin of planetary nebulae, which has transformed our understanding of the death of Sun-like stars.