Dave McComas (Southwest Research Institute and University of Texas at San Antonio)
The interstellar medium arises from material ejected as stellar winds and from cataclysmic phenomena such as novae and supernovae. The Interstellar Boundary Explorer (IBEX) directly observes neutral atoms from the local interstellar medium surrounding the Sun that penetrate our heliosphere and survive into Earth’s orbit. This material is partially ionized and the ions and neutrals interact with each other, coupling these components together and allowing various aspects of the plasma interactions between the interstellar medium and heliosphere to also imprint themselves onto the observed neutral atom distributions.
IBEX interstellar neutral observations now span six years (2009-2014) and provide a wealth of new information about the very local interstellar medium and its heliospheric interaction. In this Astrophysical Journal Supplement special issue, we collect together 14 new studies that describe the IBEX interstellar neutral results over this interval and provide other supporting and relevant observational and theoretical results. The first paper in this issue, McComas et al. 2015, lists the titles and first authors of each of the contributions; that paper also provides an overview and summary of the entire special issue and recommends the best combined interstellar parameters currently available for other researchers to use for theory and modeling studies. Each of the papers in this special issue provides great insight into various detailed aspects of the observations, interpretations, and theories related to IBEX’s unique interstellar neutral data set.
Collectively, the 14 studies in this special issue, along with the prior papers, open a completely new window on the local interstellar medium in terms of its composition, properties, and even the processes at work in the interstellar region around our heliosphere. These observations provide the ground truth for understanding the interstellar medium more generally, which is critical for stellar and planetary system formation. They also inform the formation of astrospheres around other stars and a deeper understanding of the tenuous material throughout our galaxy and the other galaxies beyond.