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3D dynamics and ejection history of dE01+09 relative to the NGC 524 group

Ascertain the three-dimensional positions and velocities of SDSS J011754.86+095819.0 (dE01+09) and the NGC 524 group and reconstruct the ejection timescale and trajectory of dE01+09 to test the proposed runaway/backsplash scenario.

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Background

The paper proposes that dE01+09 is a runaway or backsplash dwarf ejected from the NGC 524 group following environmental quenching and a strong dynamical interaction. This scenario hinges on orbital histories that cannot be robustly constrained without three-dimensional phase-space information.

The authors note that the lack of direct constraints on the 3D positions and velocities of dE01+09 and NGC 524 prevents a precise determination of the ejection timescale and trajectory, leaving a key aspect of the proposed scenario unresolved.

References

Indeed, this scenario is limited by the lack of direct constraints on the three-dimensional positions and velocities of dE01+09 and NGC 524, making the ejection timescale and trajectory uncertain.

— An isolated early-type dwarf galaxy that ran away from the group environment (2508.20459 - Paudel et al., 28 Aug 2025) in Section 4: Conclusions and Discussion (third paragraph)