Hydrogen-rich Core Collapse Supernovae

TL;DR

Hydrogen-rich core collapse supernovae, or Type II supernovae, are diverse stellar explosions linked to different progenitors, with ongoing research to better understand their origins, classifications, and observational characteristics.

Contribution

This paper reviews the classification, progenitor links, and diversity of Type II supernovae, highlighting recent observational methods to improve understanding of their origins.

Findings

Type IIP supernovae originate from red supergiants.

Type IIn supernovae are likely linked to luminous blue variables.

New observational techniques are enhancing understanding of supernova progenitors.

Abstract

Hydrogen-rich core collapse supernovae, known as "Type II" supernovae, are the most common type of stellar explosion realized in nature. They are defined by the presence of prominent hydrogen lines in their spectra. Type II supernovae are observed only in star-forming galaxies, and several events have been directly linked to massive star progenitors. Five main subclasses are identified: Type IIP (displaying a plateau in their light curve), Type IIL (displaying a light curve decline), Type IIn (displaying narrow emission lines), Type IIb (displaying increasingly strong He features with time) and 87A-likes (displaying long-rising light curves similar to that of SN 1987A). Type IIP supernovae have been robustly established as the explosions of red supergiants, while the progenitors of Type IIL's remain elusive. Type IIn's are likely linked to luminous blue variables, Type IIb progenitors may be interacting binary systems and the prototype of the 87A-like class was observed to be the explosion of a blue supergiant. The diversity in progenitor mass, metallicity, binarity and rotation is likely responsible for the diversity in observed explosion types, but the connection between progenitor parameters and supernova properties is not yet entirely understood theoretically nor fully mapped observationally. New observational methods for constraining this connection are currently being implemented, including the analyses of large samples of events, making use of very early data (obtained hours to days from explosion) and statistical studies of host-galaxy properties.