Diverse dust populations in the near-Sun environment characterized by PSP/IS$\odot$IS

TL;DR

This study reports the detection of diverse dust populations near the Sun using Parker Solar Probe's instruments, revealing impacts from various dust sources, including potential cometary material, and providing insights into the inner zodiacal dust environment.

Contribution

First direct dust impact detections inside 40 solar radii using Parker Solar Probe, identifying multiple dust populations and potential long-period cometary dust near the Sun.

Findings

Eight dust puncture events detected, mostly inside 40 solar radii.

Impact directions suggest diverse dust sources, including retrograde orbiters.

Impacts provide new constraints on the inner zodiacal dust environment.

Abstract

The Integrated Science Investigation of the Sun (IS$\odot$IS) energetic particle instrument suite on Parker Solar Probe is dedicated to measuring energetic ions and electrons in the near-Sun environment. It includes a half-sky-viewing time-of-flight mass spectrometer (EPI-Lo) and five high-energy silicon solid-state detector-telescopes (EPI-Hi). To August 2024, eight of EPI-Lo's eighty separate telescope foils have experienced direct dust puncture events, most of which occurred inside 40 solar radii (0.19 au). These impacts represent the closest ever direct dust detections to the Sun. While there is limited information about the size/mass of each impact due to the lack of a dedicated dust instrument, we can determine the impact direction for six punctures, allowing us to partially constrain the inner zodiacal abundance. Remarkably, one of six unambiguous dust impacters was likely on a retrograde orbit, suggesting long-period cometary material may survive within 20 solar radii (0.09 au). We discuss observations in the context of improving our understanding of the inner zodiacal dust environment, highlighting multiple dust populations responsible for these events, and refining hazard assessment for near-Sun spacecraft.