Detection of Bipolar Flow toward an Unusual SiO Maser Source IRAS 19312+1950

Abstract

We report a result of an interferometric observation toward an SiO maser source, IRAS 19312+1950, in the HCO+ J=1-0 line with the Berkeley-Illinois-Maryland-Association (BIMA) Millimeter Array. In the spatially integrated spectrum of HCO+, two kinematic components were seen: a strong line with a narrow width (~2 km/s, narrow component), and a weak symmetric line with a broad width (~60 km/s, broad component). The line profile of HCO+ are reminiscent of that of CO. In the integrated intensity map, we found a pronounced bipolar shape consisting of lower-velocity parts of the broad component. The higher-velocity part of the broad component originated in a relatively small region (< 3"). The spatial structure of the narrow component clearly correlated with near-infrared structure. The position-velocity diagrams indicated presence of a bipolar outflow with an expansion velocity of about 10 km/s. On the basis of the present results, we suggest that the nature of the bipolar flow seen in IRAS 19312+1950 is explained by hydrodynamical interaction between an AGB wind and ambient material with axial symmetric structure.

arXiv comment11 pages, 3 figures, accepted for publication in ApJL

References in corpus (5)

• Multiple Molecular Winds in Evolved Stars I. A Survey of CO(2-1) and CO(3-2) Emission from 45 Nearby AGB Stars
• SiO Maser Survey of Cold IRAS Sources
• Detections of SiO and H${}_2$O Masers in the Bipolar Nebula IRAS 19312+1950
• SiO Maser Survey toward the Inner Galactic Disk: 40 < l < 70 and |b| < 10
• Study of the Bipolar Nebula IRAS 19312+1950. I. Mapping Observations

Cited by in corpus (11)

• Correlation between Infrared Colors and Intensity Ratios of SiO Maser Lines
• Submillimeter Array Observation of the Proto-Planetary Nebula CRL 618 in the CO J=6-5 Line
• Disk-Like Structure in the Semi-Regular Pulsating Star, X Her
• Maser Properties of the Enigmatic IRAS Source 19312+1950
• Study of the Bipolar Nebula IRAS 19312+1950. II. Circumstellar Chemistry
• BIMA Array Observations of the Highly Unusual SiO Maser Source with a Bipolar Nebulosity, IRAS 19312+1950
• Methanol Observation of IRAS 19312+1950: A Possible New Type of Class I Methanol Masers
• Wide Field CO Mapping in the Region of IRAS 19312+1950
• BIMA CO Observation of EP Aqr the Semiregular Pulsating Star with a Double Component Line Profile
• Molecules in the peculiar age-defying source IRAS 19312+1950
• Molecular Line Observations of the SiO Maser Source IRAS 19312+1950