The complex circumstellar environment of supernova 2023ixf.

The early evolution of a supernova (SN) can reveal information about the environment and the progenitor star. When a star explodes in vacuum, the first photons to escape from its surface appear as a brief, hours-long shock-breakout flare, followed by a cooling phase of emission. However, for stars exploding within a distribution of dense, optically thick circumstellar material (CSM), the first photons escape from the material beyond the stellar edge and the duration of the initial flare can extend to several days, during which the escaping emission indicates photospheric heating.

Co-operative learning processes of students: a longitudinal multilevel perspective.

Background: This article describes the outcomes of a longitudinal, multilevel observational study in which the relationship between the processes of co-operation and giving explanations was compared between classes trained in communication skills and classes that were untrained.

Aims: This study examined the effects of training in basic communication skills on the processes of co-operation and giving explanation in co-operative groups. In particular, the study investigated: (a) How the processes of co-operation and giving explanations develop over time; (b) How the underlying processes of co-operation and giving explanations are related; (c) Which factors at the student and class level facilitate or hinder these processes.