Three new candidate ancient planetary nebulae, each several arcminutes across with extremely low [O iii] surface brightness around 30 mag arcsec^{-2}, were discovered using amateur telescopes, with candidate central stars yielding age estimates of 50-100 thousand years.
Quantifying Symmetry: Transformation Information for Planetary Nebulae and Supernova Remnants
4 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
We present a quantitative symmetry-identification pipeline for astrophysical images based on Transformation Information (TI), an information measure of self-similarity under geometric transformations. TI is expressed as a Kullback-Leibler (cross-entropy) divergence between an image and its rotated or reflected counterpart on the overlapping domain. By scanning rotation angles and reflection axes, we obtain TI curves whose local minima identify symmetry operations. We validate the method on a wind-rose pattern and then apply it to planetary nebulae, where the recovered axes trace bipolar and multipolar lobes consistent with morphology-based classifications. Applying TI to supernova remnants yields estimate axes associated with protrusions, rims, and substructure. To emphasize global morphology, we introduce a thresholded two-level variant that compares binary silhouettes and can reveal outline-driven symmetries. Finally, we quantify symmetry using a minima prominence-to-width score and show that this compact descriptor separates Type Ia and core-collapse remnants into distinct populations for an X-ray sample. TI provides a non-parametric, reproducible framework for symmetry identification, classification and population studies.
years
2026 4verdicts
UNVERDICTED 4representative citing papers
Morphological similarity between JWST images of planetary nebula PMR 1 and X-ray images of CCSN remnant RCW 103 indicates that two pairs of jets shaped RCW 103, supporting the jittering-jets explosion mechanism.
Analysis of JWST observations identifies point-symmetric morphology in SNR 0540-69.3 ejecta, interpreted as evidence for shaping by at least three jet pairs in the jittering-jets explosion mechanism.
Morphological similarity between pipe features in PNe and CCSNRs and a jet simulation is used to argue that jets formed the pipes and to bolster the JJEM for core-collapse supernovae.
citing papers explorer
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Ancient 'ghost' planetary nebulae discovered with amateur telescopes
Three new candidate ancient planetary nebulae, each several arcminutes across with extremely low [O iii] surface brightness around 30 mag arcsec^{-2}, were discovered using amateur telescopes, with candidate central stars yielding age estimates of 50-100 thousand years.