Abstract Accurate distance measurements to supernova remnants (SNRs) are crucial for understanding their physical properties and evolution. We present a novel method that combines CO line observations with three-dimensional extinction maps to determine distances to SNRs (G93.7−0.2, G109.1−1.0, G156.2+5.7, and G166.0+4.3) through their associated molecular clouds. For each SNR, candidate CO velocity components corresponding to interacting molecular clouds are identified based on previous observational evidence with refinements: −19, −3 km s −1 for G93.7−0.2, −51, −46 km s −1 for G109.1−1.0, −10, 0 km s −1 for G156.2+5.7, and −27, −15 km s −1 for G166.0+4.3. By examining extinction-distance profiles along the sightlines and identifying extinction jumps that spatially coincide with CO emission features, we derive distances of 1.82 ± 0.13 kpc for G93.7−0.2, 3.05 ± 0.15 kpc for G109.1−1.0, 0.60 ± 0.15 kpc for G156.2+5.7, and 3.44 ± 0.23 kpc for G166.0+4.3. Our extinction-based distances are largely consistent with previous estimates while with better accuracy and robustness.
张 et al. (Tue,) studied this question.