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The solar analogs of M67 let us glimpse the probable behavior of the Sun ontime scales surpassing the duration of human civilization. M67 can serve as asolar proxy because its stars share a similar age and composition with the Sun.Previous surveys of M67 observed that 15% of its Sun-like stars exhibitedchromospheric activity levels below solar minimum, which suggest that thesestars might be in activity-minimum states analogous to the Maunder Minimum. Theactivity diagnostic used, the HK index (relative intensities of the Ca II H&Klines integrated over 1 Ang. bandpasses), was measured from low-resolutionspectra ($R\approx 5000$), as is traditional and suitable for nearby, brightstars. However, for stars beyond the Local Bubble, the interstellar medium(ISM) imprints absorption lines in spectra at Ca II H&K, which negatively biasactivity measurements when these lines fall within the HK index bandpass. Imodel the ISM clouds in the M67 foreground with high-resolution spectra of bluestragglers and solar analogs. I demonstrate that ISM absorption varies acrossthe cluster and must be accounted for on a star-by-star basis. I then apply theISM model to a solar spectrum and broaden it to the lower spectral resolutionemployed by prior surveys. Comparing HK indices measured from ISM-free andISM-contaminated spectra, I find that all stars observed below solar minimumcan be explained by this ISM bias. I conclude that there is no compellingevidence for Maunder minimum candidates in M67 at this time.

No "Maunder minimum" candidates in M67: mitigating interstellar contamination of chromospheric emission lines