FAST Search for Circumstellar Atomic Hydrogen. II. Is BD+30°3639 an Interacting Planetary Nebula?

Abstract The young, compact, very high surface brightness but low excitation planetary nebula (PN) BD+30°3639 is one of the few PNe that have been reported to exhibit 21 cm H i emission line. As part a long-term program search for circumstellar atomic hydrogen, we observed feature toward with Five-hundred-meter Aperture Spherical radio Telescope (FAST). Assuming direct association between PN and detected emission, these new observations show this surrounding significantly more spatially extended than indicated by previous interferometric can be resolved into two velocity components. estimated mass larger 100 M ⊙ , invalidating an origin from host star itself or its ejecta emitting material. We discuss possibility stems interstellar medium (ISM) swept out over time stellar wind. Moreover, report tentative detections absorption features lying near blueward systemic PN, which are probably stalled asterosphere at outer boundary expanding ionized region. gas producing insufficient solve so-called “PN missing problem.” demonstrate capability FAST investigate interaction process ISM.