The Crab Nebula Revisited Using HST/WFC3

TL;DR

This study presents new high-resolution HST/WFC3 observations of the Crab Nebula, comparing them with past data and JWST imagery to analyze its dynamic structure and discover new filament groupings.

Contribution

It provides updated, high-resolution imaging of the Crab Nebula, revealing previously unrecognized filament groupings and enabling detailed comparison across multiple wavelengths.

Findings

Identification of two new filament groupings with similar emission characteristics.

Comparison of HST and JWST data enhances understanding of nebula dynamics.

Detection of nearly diametrically opposed filament groups from the pulsar.

Abstract

It has been over 24 years since the iconic Crab Nebula has been visited by the high spatial resolution eye of the Hubble Space Telescope. The expanding nebula is dynamic on these timescales, with many of the outer filaments of the nebula known to show proper motions of 0.3'' or more per year. Over time, it has become increasingly difficult to compare the fine scale structure of the nebula with recent data at other wavelengths. We have re-observed the Crab in an HST Cycle 31 program using the WFC3 camera and filters similar to those previously used to make the existing mosaic that dates from 1999-2000 and was obtained with the WFPC2 camera. Two central fields were observed with the F487N filter, providing an uncontaminated hydrogen band for comparison. We also observed two primarily continuum band filters (F547M and F763M), allowing us to study the optical synchrotron nebula component of the Crab's emission. We compare these new data to the first epoch of WFPC2 data as well as to more contemporaneous NIR/MIR imagery from JWST. Finally, we highlight two previously unrecognized groupings of filaments with similar emission characteristics that are nearly diametrically opposed from the pulsar but whose origin remains uncertain.