Speaker #1 — Jeff Linsky
What lies just outside of the heliosphere and why this is important for explaining the recent detection of 60Fe in Antarctic snow
Koll et al. (Phys Rev. Let 123, 072701 (2019)) recently reported the detection of 60Fe in interstellar dust grains found in Antarctic snow accumulated over the last 20 years. How can this unexpected discovery of supernova debris be explained? I will propose two possible explanations based on our study of warm interstellar gas clouds that are in contact with and shape the outer heliosphere. The warm partially ionized gas close to the Sun can be studied from the inflow of neutral helium into the inner solar system and also by the flow of interstellar gas determined from absorption lines formed in the interstellar medium. These two techniques appear to give conflicting results. We propose a model consistent with both data sets that shows that the outer heliosphere is in contact with 4 interstellar clouds. We propose that the measured 60Fe in Antarctic snow can be explained by the inflow of large dust grains from these clouds that are in contact with the outer heliosphere. This could be continuous injection of 60Fe containing dust grains at a low level or by an unusual event seen in the 2005 Ulysses data. The two possibilities and the historical record of the Sun’s motion through the local ISM can be tested by further studies of older snow and ice samples.
Speaker #2 — Joe Bright
title and abstract TBA