Water Production Rates from SOHO/SWAN Observations of Comets C/2017 K2 (PanSTARRS) and C/2022 E3 (ZTF)

TL;DR

This study utilizes SOHO/SWAN observations to measure water production rates from comets C/2017 K2 and C/2022 E3, providing insights into their activity over time through hydrogen Lyman-alpha imaging.

Contribution

It introduces a method to derive comet water production rates from SOHO/SWAN hydrogen Lyman-alpha data, covering long-term activity periods.

Findings

Water production rates were successfully calculated for both comets.

The observations covered significant periods around perihelion and post-perihelion.

Results enhance understanding of cometary activity and solar wind interactions.

Abstract

In 2022 and 2023 the hydrogen comae of two long period comets, C/2017 K2 (PanSTARRS) and C/2022 E3 (ZTF), were observed with the Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyman-alpha camera on the SOlar and Heliosphere Observer (SOHO) satellite. SWAN obtains nearly daily full-sky images of the hydrogen Lyman-alpha distribution of the interstellar hydrogen as it passes through the solar system yielding information about the solar wind and solar ultraviolet fluxes that eat away at it by ionization and charge exchange. The hydrogen comae of comets, when of sufficient brightness, are also observed. Water production rates have been calculated over time for each of these comets, covering about 6 months mostly of the post-perihelion period of C/2017 K2 (PanSTARRS) and about 3 months around perihelion of C/2022 E3 (ZTF).