Bima CO observation of EP aquarii: The semiregular pulsating star with a double-component line profile

Abstract

This paper reports the results of a Berkeley-Illinois-Maryland Association array interferometric observation of EP Aqr, a semiregular pulsating star with a double-component line profile in the CO J = 1-0 line. The broad component shows a flat-topped profile, and the narrow component shows a spiky strong peak. Although previous single-dish observations suggested that the CO J = 2-1 line exhibits a Gaussian-like profile, the CO J = 1-0 line does not. The spatial distributions of both the narrow and the broad components appear to be roughly round with the same peak positions. No significant velocity gradient is seen. The spatial-kinetic properties of the molecular envelope of EP Aqr are reminiscent of a multiple-shell structure model rather than of a bipolar flow and disk model. A problem with this interpretation is that no evidence of interaction between the narrow- and broad-component regions is seen. A Gaussian-like feature seen in the CO J = 2-1 line might play a key role in understanding the spatiokinetic properties of the molecular envelope of EP Aqr. © 2006. The American Astronomical Society. All rights reserved.