Abstract

The observed ratio of Wolf–Rayet (WR) star subtypes (e.g., WC/WN) in M31 is significantly higher than the predictions of standard stellar evolution models, yet this key diagnostic discrepancy remains unresolved. This is partly due to incomplete census and the challenge of resolving individual stars in compact clusters with ground-based telescopes. In this work, we report a young cluster with WR features with the (R.A., Dec) = (00:43:39.36, +41:10:08.7), discovered with LAMOST spectra. We use the high spatial resolution of the HST imaging data to resolve the cluster members, leading to the identification of four WR star candidates, four OB stars, and one yellow supergiant. Based on the current known WR sample in M31 observed in the HST F275W filter, about one-third of WRs are contaminated by other sources within a 1.″1×1.″1 aperture, while this fraction can reach up to two-thirds for the LAMOST fiber size of 3.″3. Applying the approach demonstrated in this work to a larger sample of crowded regions in M31 will yield a more complete census and allow for the measurement of a definitive WC/WN ratio, corrected for contamination. Whether this refined ratio increases or decreases the current tension with models remains to be seen, but it will provide the essential observational constraint needed to advance our understanding.

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