The Crab Nebula Revisited Using HST/WFC3

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.

💡 Research Summary

This paper presents a new epoch of high-resolution optical imaging of the Crab Nebula, observed with the Hubble Space Telescope’s (HST) Wide Field Camera 3 (WFC3) in 2024. The primary motivation was to revisit this iconic supernova remnant after a 24-year gap since the last comprehensive HST mosaic was taken with the WFPC2 camera in 1999-2000 (Epoch 1). This significant time baseline allows for the study of the nebula’s proper motions and structural changes, while the new data also provide a crucial optical reference for comparison with contemporary multi-wavelength observations, particularly from the James Webb Space Telescope (JWST).

The observations were conducted under HST Cycle 31 program 17500. The team observed six overlapping fields covering the nebula using filters chosen to closely match those used in the earlier WFPC2 mosaic: F502N for